CSCD来源期刊

北大中文核心期刊

中国科技核心期刊

地学领域高质量科技期刊分级T2区（2023）

世界期刊影响力指数报告Q1区（2023）

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Study on the response of dynamic water pressure landslide to rainfall in the Three Gorges Reservoir Area -- A case study of Bazimen Landslide
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240697
Abstract PDF icon22 icon1
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[Objective]To explore the response law of dynamic water pressure landslides to rainfall, [Methods]taking the Bazimen landslide in the Three Gorges Reservoir area as an example, combined with geological survey data, correlation analysis, and finite element numerical simulation, the influence of rainfall on landslide deformation was systematically studied, revealing its response law and deformation mechanism. [Conclusion]Research has shown that fluctuations in reservoir water and rainfall are the main driving factors for the deformation of the Bazimen landslide. The impact of rainfall on landslide deformation is manifested as follows: during the stage of reservoir water decline, rainfall replenishes the internal water head of the slope, further enhancing the effect of dynamic water pressure and significantly exacerbating slope deformation; During the rising stage of reservoir water, rainfall infiltrates to the rear edge of the secondary sliding zone, causing an increase in pore water pressure, which in turn triggers deformation of the landslide rear edge and drives overall deformation of the landslide. Adequate rainfall is the main triggering factor for landslide deformation during the rising stage of reservoir water. The deformation of landslides exhibits a certain lag, with a lag time of about 20 days for deformation caused by a decrease in reservoir water and 9 days for deformation caused by rainfall. The attenuation degree of landslide stability coefficient (1.029) under the condition of long-term continuous rainfall is higher than that under the condition of rainstorm (1.039). The research results have deepened the understanding of the deformation mechanism of dynamic water pressure landslides and can provide reference for the early warning and prediction of such landslides.
CO2 sequestration in deep saline aquifers with integrated thermo-hydro-mechanical model
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240772
Abstract PDF icon25 icon3
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[Objective] Carbon capture and storage (CCS) is crucial in combating global climate change, and deep saline aquifers have the largest identified storage potential, making them the preferred storage location. However, when CO2 is injected underground, it tends to escape through interconnected fractures or reactivated faults toward the ground due to buoyancy. Thus, studying the impact of CO2 injection on fault and the feedback effect of fault activation on CO2 leakage is significant. [Methods] In this paper, we develop a fully coupled two-phase thermo-hydro-mechanical model to simulate mutual interactions between CO2 injection, fault failure, and CO2 plume propagation. [Results] Modeling results demonstrate that the permeability distribution exhibits a notable dichotomy upon fault activation. Furthermore, the evolution of fault permeability is intimately coupled with the spatio-temporal changes in the pore pressure field. As the initial failure zone transforms into a high-permeability area, it facilitates the release of pore pressure, dampening further fault activation, and leading to localized activation characteristics. In addition, the migration range of CO2 plumes cannot be trivially equated with the cooled zone in the rock mass. The plume dispersal is rapid and extensive, reaching a frontal migration distance of up to 1500 m after just two years of constant injection. In contrast, the diffusion of the temperature field is slow and concentrated, yielding a cooled area of only 200 m after 20 years of constant injection. This constrained temperature field pattern is less prone to inducing fault activation, thereby contributing to the long-term safety of carbon sequestration projects. Finally, fault configuration exerts a significant influence on the long-term safety of CO2 storage, with reverse faults exhibiting the best sealing performance, normal faults the worst, and strike-slip faults falling in between. Specifically, the effective CO2 storage capacity of the reverse fault is approximately 25% higher than that of the normal fault. [Conclusion] In conclusion, the established two-phase thermo hydro mechanical model incorporating damage behavior demonstrates robust performance, accurately capturing the intricate interaction mechanisms between fault progressive failure and CO2 plume migration. This model provides both theoretical and technical support for the long-term safety assessment of carbon sequestration projects.
Construction and Application of Earthquake Disaster Knowledge Graph Fusing and Multimodal Data
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240334
Abstract PDF icon79 icon13
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[Objective] Earthquakes pose a major threat to the safety of human life and the integrity of property, while they are also considered to be one of the main catalysts of various geological disasters. Given their potential impact, analysing and integrating information related to earthquake disaster has become an important task in supporting effective decision-making processes. However, earthquake disaster observation data are usually heterogeneous from multiple sources, which contain different scientific knowledge and low correlation between the data. This makes it difficult to use the information effectively for integration and querying. [Methods] A promising approach to these challenges is the use of the Semantic Web, of which the most exemplary approach is Knowledge Graph. Knowledge graph offer significant advantages in fusing and representing heterogeneous data from multiple platforms and disciplines. Considering the need for consistency between entity structures, while recognizing the diversity of information in the earthquake disaster domain, a structured approach was adopted. Firstly, a top-down approach was used to provide a systematic overview of concepts related to the earthquake disaster domain. This included the construction of a comprehensive ontology with several key components: earthquake disaster data, geological and geographic contexts, specific earthquake disaster events, emergency response tasks associated with these disasters, and models relevant to understanding and predicting earthquake behaviors. An earthquake disaster ontology layer was created. A bottom-up approach was adopted, aiming to create a high-quality data layer. In order to analyze the surface changes caused by earthquake activity before and after the disaster, a convolutional neural network was utilized to achieve a complex transformation from image data to structured textual knowledge based on remote sensing data. In addition, a fine-tuned Universal Information Extraction (UIE) pre-trained model was used. The model helps in recognizing named entities and extracting relational attributes from unstructured text data with extraction accuracies of 82.04% and 70.66% respectively. After the extraction phase, data fusion and unified representation is achieved by evaluating the semantic similarity of word vectors corresponding to the extracted entities and attributes. [Results] Taking the earthquake of 18 December 2023 in Jieshishan County, Linxia Prefecture, Gansu Province as an example, a high-quality earthquake disaster knowledge graph is formed through ontology construction, data extraction, and unified expression, and the transformation from multi-source heterogeneous seismic data of earthquake disaster to unified knowledge expression is achieved. [Conclusion] By building a knowledge graph of earthquake disaster, functions such as querying disaster loss data, providing decision support for the entire emergency response chain, and facilitating reasoning and querying about potential secondary hazards were realized. This reasoning capability is enhanced by integrating relevant geological data. The innovative approach presented in this paper utilizes deep learning techniques and pre-trained models to effectively fuse multimodal data and ultimately support the construction of an earthquake disaster knowledge graph, which helps to improve the ability to quickly and accurately query earthquake disaster information, thereby supporting proactive measures to respond to the occurrence of secondary disasters. This integrated approach not only facilitates immediate post-disaster analyses, but also lays the foundation for future advances in disaster management and response methods.
Hydrothermal Sandstone Geothermal Reservoir Evaluation of the Key Oil Area in the Songliao Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240530
Abstract PDF icon63 icon3
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[Purpose] The current industry evaluation standards for geothermal reservoirs are formulated based on hydrothermal with excellent storage capacity (medium-high porosity and medium-high permeability). According to these standards, most of the geothermal reservoirs in China's basins are classified as hydrothermal reservoirs with poor storage capacity (characterized by medium-low porosity and low permeability), thus making the existing standards inapplicable. In addition, during the pre-feasibility exploration stage of geothermal resources, the commonly used evaluation methods require a large number of parameters and data. However, the information available at this stage is often limited. Therefore, it is necessary to explore rapid evaluation methods with fewer parameters. The hydrothermal sandstone reservoirs in the key oil areas of the Songliao Basin have the characteristics of medium-thin layers, medium-low porosity, and low permeability. They belong to hydrothermal with excellent storage capacity. Taking these as an example, this paper will study the evaluation standards of hydrothermal with poor storage capacity reservoirs and explore rapid evaluation methods for reservoirs under the condition of fewer parameters. [Methods] Firstly, based on understanding the basic characteristics of the thickness, porosity, and permeability of the target layer reservoir, statistical analysis was conducted. The golden section method was applied to classify the levels and determine the evaluation standards for these parameters. Secondly, since the temperature differences of the geothermal reservoirs are not significant and they all belong to low-temperature reservoirs, the daily production of a single well is more important for the evaluation of the geothermal reservoir. The thickness of the sand bodies, porosity, permeability, and daily production of a single well in the development area are selected. A multivariate linear regression analysis is used to analyze these data, construct a geothermal reservoir evaluation formula, calculate the scores of each evaluation unit, and divide the grades according to the golden section method. [Results] The score ranking of this method was compared pairwise with the score rankings of two existing evaluation methods. It was found that incorporating the thickness of the sand bodies while discarding temperature is reasonable. Moreover, the standard deviation of the scores obtained by this method is relatively large, which can better reflect the differences among the evaluation units. Therefore, this method is more feasible, and the evaluation criteria formulated for hydrothermal with poor storage capacity are more reasonable. [Significance] The evaluation criteria for hydrothermal with poor storage capacity determined in this paper have certain reference significance for the evaluation of geothermal reservoirs in other basins. Considering the differences between basins, the few-parameter rapid evaluation method determined in this paper may not be applicable to other basins. However, the process of determining the evaluation formula is worth learning from.
Suitability and potential evaluation of geological storage of carbon dioxide in saline aquifer of Ying-Qiong Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240366
Abstract PDF icon82 icon9
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[Objective] Excessive carbon dioxide (CO2) emissions have caused global climate variability, leading to a series of environmental problems. As a key technology to reduce CO2 emissions, carbon capture, utilization, and storage (CCUS) plays an important role in relieving large-scale CO2 emission reductions, and the application of CO2 storage projects for the saline aquifer in offshore China has a broad application prospect and great technical and economic potential. [Methods] To address the problem of unclear understanding of the favorable areas and storage potential of CO2 in the saline aquifers in the Ying-Qiong Basin, the suitability evaluation of geological storage of CO2 is carried out by calculating the weights of the indicator components and the suitability score based on the geological characteristics of the Ying-Qiong Basin. In addition, the CO2 storage potential of the saline aquifer in the Ying-Qiong Basin is preliminarily evaluated by combining the effective CO2 storage coefficients calculated by the numerical simulation method and different storage potential calculation methods. [Results] Results show that the storage capacity obtained from EC method is less than that determined by the USDOE and CSLF methods. Since both of the CSLF methods consider the storage mechanisms such as geological structure storage, residual gas storage, and dissolution storage, the results seem more reasonable. [Conclusion] In summary, the CO2 storage potentials of the saline aquifer in the Yinggehai Basin and Qiongdongnan Basin are 7.96×106 and 4.40×106 million tons, respectively, and the total CO2 storage potential in the saline aquifer in the Ying-Qiong Basin is 1.24×107 million tons, which further verifies the great potential of the industrial-scale pilot and demonstration projects of CO2 storage in the saline aquifer of the Ying-Qiong Basin and provides a good opportunity for the next step of carrying out the CO2 storage project in the saline aquifer of the Ying-Qiong Basin.
Research progress on trajectory control technology for geological core drilling
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240373
Abstract PDF icon88 icon5
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Geological core drilling is one of the important technical means for geological exploration, and the actual drilling trajectory of the borehole is an important parameter of drilling quality. It not only affects the safety inside the borehole during drilling construction, but also relates to the quality and accuracy of geological exploration. The limited conditions such as small bore diameter, low pipe strength and continuous geological coring which lead to difficult to control the drilling trajectory. Based on the analysis of the characteristics of geological core drilling, the trajectory control methods of geological core drilling were systematically sorted out, classified and summarized. The following research results are obtained. First, The primary goal of primary directional hole is to obtain the core of the target layer, analyzed the design method of parameters such as the inclination angle, orientation, displacement, etc. of the borehole and their variation with depth, and clarified the applicable conditions and drawbacks, provided ideas for the use of primary directional hole in drilling construction less than 500m, and pointed out that deep holes should be used in conjunction with other measures. Second, in terms of packed hole assemble for geological drilling, analyzed the usage of conventional hole assemble and large-diameter hole assemble, and proposed the mechanical theory of wire coring string with packed hole assembly.Third,around controlled directional drilling technology, analyzed the application in drilling deviation correction and lateral drilling obstacle avoidance, pointed out the advantages and disadvantages of different methods,indicating that small diameter bottomhole power drilling tools have obvious advantages. However, due to the requirements of geological coring technology, they have many limitations in geological core drilling.Through a review and analysis of the current status of geological core drilling trajectory control technology, clear identification of key factors affecting drilling trajectory and various techniques for controlling drilling trajectory, which can provide useful references and research ideas for improving the exploration accuracy of geological drilling.
Application of LithoScanner logs in recognition and evaluation of coaly source rocks
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240386
Abstract PDF icon63 icon2
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[Objective] In the Kuqa Depression, the Triassic and Jurassic periods feature five sets of source rock sequences that developed as alternating lake and swamp facies. Based on lithology, these sequences can be divided into coal, carbonaceous mudstone, and dark mudstone. The source rocks are characterized by high TOC abundance, significant thickness, and extensive distribution. Due to the multiple vertically distributed layers of source rocks and the strong heterogeneity in lithological distribution, conventional methods like the ΔlgR method have shown poor performance in TOC logging quantification. [Methods] To better understand the hydrocarbon resource potential and assess the reserves in the Kuqa Depression, this study first identified the lithological characteristics of the source rocks through core analysis. Further geological characterization of the source rocks was achieved via geochemical analysis data. Initially, the ΔlgR method was applied to quantitatively evaluate TOC logging, and LithoScanner logging was used for lithological identification of the source rocks. Further, LithoScanner logging was employed to achieve quantitative TOC logging evaluation. [Results] Overall, the Triassic and Jurassic periods are dominated by type II1, II2, and III organic matter, with medium to high maturity, and the quality of these source rocks ranges from medium to good. The method of using LithoScanner logging to identify different lithological source rocks and quantitatively evaluate TOC demonstrated significantly higher accuracy compared to the ΔlgR method. [Conclusion] The research findings provide valuable guidance for assessing the hydrocarbon resource potential in the Kuqa Depression and expand the application scope of LithoScanner logging data.
Research advances in the “end effect” of ore forming
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240387
Abstract PDF icon69 icon3
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As a front subject in the study of geology of ore deposits and geomechanics of ore fields, the “end effect” of ore forming has attracted more and more attention from experts and scholars. The research contents of the “end effect” of ore forming mainly include the “end effect” of ore-forming structures and that of ore-forming fluids: as for the former, the “end effect” of multi-scale ore-controlling structures in different tectonic settings as well as their role in controlling ore fields and ore deposits (bodies), especially the structural types, mechanical properties, and rock- and ore-controlling mechanisms of the “end” of deposit-level ore-controlling structures, the trapping effect of ore-forming fluids, and the location mechanism of ore deposits (bodies), is studied based on the structural analysis of geomechanics of ore fields and in combination with structure-(alteration) lithofacies mapping technique and geophysical probing technique; as for the latter, the characteristics of ore-forming fluids can be reflected through study of fluid inclusions and isotopes and the temporal and spatial evolution process of the “end” of ore-forming fluids can be finely depicted through study of zoning effect of the “end” of ore-forming fluids, thus revealing the restriction of physicochemical conditions of structures on ore-forming process. From the perspective of the coupling relationship between the “ends” of ore-forming structures and ore-forming fluids, an in-depth study can be made in the rock- and ore-controlling mechanisms under the “end effect” of structures and the genetic relation of structure-fluid coupled ore forming through close combination of study of geology of ore deposits and fluid geochemistry, structural analysis of ore fields, and geophysical prospecting technique, thus providing a basis for the prediction for deep ore prospecting.
Hydraulic Tomography in a Typical Basin-scale Aquifer of Groundwater Overexploitation Control in Hebei Province
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240709
Abstract PDF icon80 icon2
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One of the main challenges in characterizing the heterogeneity of large-scale aquifers using hydraulic tomography is to find an effective excitation that can significantly affect regional groundwater dynamics. Logically, variations of human-induced groundwater exploitation amounts may be a feasible option.This research selected the Handan Eastern Plain as the study area, one of the pilot areas for groundwater over-exploitation control in Hebei Province. Hydraulic tomography was applied to a two-dimensional confined aquifer by utilizing aquifer responses caused by reduced exploitation, and the effects of prior geological information and observation well configuration on parameter estimations were further discussed. Results showed that hydraulic tomography could effectively characterize the heterogeneity of large-scale aquifers, and accurate information of geological zonation could significantly improve parameter estimations. Correlation scales and variances have insignificant effects on the inversion results. In order to improve the precision of aquifer parameter estimation, the prior geological information and existing borehole data should be given full consideration, and new observation wells should be added into the existing monitoring network in the areas where there are significant changes in hydrogeological settings.This novel method for characterizing the heterogeneity of large-scale aquifers based on the concept of hydraulic tomography, is cost-effective for mapping large-scale aquifer heterogeneity with significant economic and social benefits, because it can save the huge time and manpower cost yielded by extra drilling and pumping tests by intelligently collecting the dataset of groundwater pumping and observation at the existing wells with reduced exploitation in the Hebei Province.
The Evolution of Continental Weathering and Upwelling in Early Silurian and the Implications for the Organic Matter Accumulations in the Shales of Longmxi Formation
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240678
Abstract PDF icon71 icon9
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Abstract: The organic-rich shales in the Early Silurian Longmaxi Formation are the important source rocks in South China, however, the deposition mechanism of these shales is still under debate. [Objective] In order to reconstruct the climatic and oceanic environments during the Early Silurian, and investigate the influence of significantly geological events (especially the continental weathering and upwelling) on the organic matter accumulation, [Methods] this study presents the geochemical compositions of the Lower Silurian succession of the Upper Yangtze Platform (BD1 core, Butuo district). [Results] The results show that the Longmaxi period experienced a transition from weak chemical weathering intensity in early period to intense chemical weathering intensity in later period. In addition, the Longmaxi Formation in studies area is characterized by restriction ocean. This study posits that early Longmxi sediments exhibited low chemical weathering intensity and more congruent weathering, while Aeronian sediments were characterized by intermediate chemical weathering intensity and incongruent weathering. Given that the gradual enrichment of oxygen within bottom waters can be supported by the redox condition proxies, this study suggests that congruent weathering-induced high paleoproductivity in early Longmaxi is the primary factor accelerating anoxia and further the enrichment of organic matter. [Conclusion] In summary, there is obvious differences between the deposition of Longmaxi shales in different areas, and this study suggests that the weathering-induced high productivity contributed to the deposition of organic-rich shales, while the upwelling likely triggered the organic matter accumulations in Longmaxi shales in the outer shelf, instead of inner shelf.
Fine characterization of the internal structure of typical fault-fracture reservoir outcrops in Xunyi area, Ordos Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240522
Abstract PDF icon48 icon9
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[Objective] The fault-fracture reservoir in the southern Ordos Basin have large reserves, high oil abundance, and good development prospects. However, their internal structures are complex and varied, and the existing research results cannot support a detailed description of fault-fracture reservoirs. [Methods] In order to clarify the internal structural characteristics of the fault zones and construct a fine fault zone development model, this paper uses unmanned aerial vehicle oblique photography technology to conduct high-precision sampling and modeling of various typical fault-fracture reservoir outcrops in Xunyi area. We use self-developed software to collect and analyze three-dimensional data of the fault-fracture reservoir, and further study its internal structural characteristics and fracture development patterns. [Results]The results indicate that: (1) There are three types of fracture bodies developed in the Xunyi area: transtensional segment (half-negative flower pattern, graben pattern), pure strike-slip segment (closed translational pattern), and compression twisting (horst pattern); (2) Based on the comprehensive parameters such as the development of faults, rock morphology, and fracture development characteristics in the field outcrop, fault-fracture reservoir are divided into sliding breaking zones, induced fracture zones, and substrate zones. The structural patterns and quantitative rules of different types of fault-fracture reservoirs vary greatly, with only half-negative flower pattern and graben pattern fault-fracture reservoirs developing wide sliding breaking zones; (3) The fracture density is affected by the fault-fracture reservoir types，separation，fault spacing，block position，and sand layer thickness. Overall, the highest density is found in the graben type fault-fracture reservoir, followed by the half-negative flower patterned fault-fracture reservoir, and the lowest is found in the closed translational and horst type fault-fracture reservoirs; The larger the fault distance, the smaller the fault spacing, and the lower the rock thickness, the more developed the fracture; In the same fault-fracture reservoir, the density of fracture in different blocks shows different trends of variation. [Conclusion] This study identified four patterns and quantitative rules of fault-fracture reservoirs, summarized the influence of different factors on fracture density, and provided more accurate quantitative structural characteristics of fault-fracture reservoirs for underground reservoir characterization.
Simulation study on the effect of fault on COD migration in groundwater of landfill - A Case Study of Longhua Energy Ecological Park in Shenzhen
PEI Hongjun
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240731
Abstract icon108
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Fault is an important channel for the migration and diffusion of groundwater flow and pollutants. However, there are few researches on the simulation of groundwater pollution migration of landfill by fault at home and abroad. [Objective]The purpose of this paper is to build a groundwater flow and solute transport model including fault permeability，[Methods] based on GMS software to simulate and predict the impact of characteristic pollutant seepage on groundwater environment and water delivery tunnel under different working conditions. [Conclusion]The simulation results show that under normal working conditions, due to the anti-seepage measures at the bottom of the plant, the diffusion range of pollutants is basically limited to the inside of the plant, and the maximum concentration of pollutants in the center is less than 0.5 mg/L. Under abnormal conditions, the pollutants in the leakage scenario of pollution source No. 1, No. 2 and No. 3 diffuse to the location of the water delivery tunnel on the 800th, 4015th and 1095 days, respectively. The vertical diffusion range of pollutants in the three simulated scenarios gradually increases, but there is little difference in the plane diffusion range. On this basis, i the simulation of groundwater pollution caused by the enhancement of the permeability of the fault zone is carried out. The results show that the enhancement of the permeability of F4 fault has a great environmental risk to the pollutant migration under the pollution source scenario No. 1 and No. 3. Under the No. 2 pollution source scenario, the enhanced permeability of F3 fault does not bring greater environmental risk to the tunnel area. The research in this paper can provide scientific support for groundwater pollution prevention and risk assessment in the study area.
Effects of inorganic salts on pore structure and permeability of undisturbed loess under dry and wet cycling conditions
LI Peiyue，HE Qiang，WU Jianhua，CHEN Yinfu，KOU Xiaomei，TIAN Yan
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240711
Abstract icon134
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[Objective] The infiltration of inorganic salt solutions during dry and wet cycles exerts a significant influence on the structural strength and safety stability of loess masses. The aim of this research is to disclose the impact of inorganic salts on the pore structure and permeability of undisturbed loess under the effect of dry and wet cycles. [Methods] In order to fulfill this research objective, this study centered on the loess from the South Plateau in Jingyang County, Shaanxi Province. By employing laboratory experiments, this study systematically analyzed the variation law of the permeability and pore structure of undisturbed loess under diverse dry and wet cycling conditions and different concentrations of sodium chloride inorganic salt solution, as well as its mechanism of soil and water interaction. [Results] The findings indicated that dry and wet cycles diminished the permeability of undisturbed loess, and the saturated permeability coefficient of undisturbed loess decreased with the increment in the number of dry and wet cycles. The sodium chloride solution augmented the permeability of undisturbed loess, and the enhancement of permeability became more pronounced with the rise in the concentration of the sodium chloride infiltration solution. [Conclusion] Dry and wet cycles facilitated the development of fissures on the surface of undisturbed loess, augmenting the number and area ratio of micropores in the soil, thereby reducing the effective porosity of the soil mass and rendering the soil structure more compact. The infiltration of the sodium chloride solution promoted the dissolution of minerals such as gypsum and rock salt, leading to more developed soil pores and increased permeability. This study enriches the comprehension of the variation law of loess structure and permeability under the combined action of dry and wet cycles and inorganic salt solution infiltration, furnishing scientific support for soil and water conservation and engineering construction in loess regions.
Rapid seismic damage assessment of reservoir dams based on BO-GBDT
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240425
Abstract PDF icon94 icon7
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Reservoir dams are major lifeline projects, and how to quickly and effectively conduct seismic damage assessment of reservoir dams after an earthquake is of great significance for the development of rescue programs and post-disaster restoration. In order to quickly and accurately assess the damage status of reservoir dams that have been subjected to earthquakes., we select the details of the earthquake damage of each reservoir dam in Wenchuan 8.0 magnitude earthquake, and construct a sample dataset by combining the structural characteristics of the dams and the intensity of the earthquake. The missing values of the samples are processed using k-nearest neighbor interpolation, and the relevance of the sample features is judged. In this paper, we propose a rapid assessment model of earthquake damage of reservoir dams based on the gradient boosting tree algorithm.Four hyperparametric optimization methods, namely Grid Search (GS), Particle swarm optimization (PSO), Bayesian optimization (BO) and HyperBand Search (HS), are used for the Gradient Boosting Tree (GBDT) regression algorithm for parameter optimization, and the models were compared according to their performance metrics (coefficient of determination R2, root mean square error RMSE, mean error MAE) and ranked in terms of feature importance. The results show that the BO-GBDT model can assessment the degree of earthquake damage of reservoir dams with the shortest time consumption as well as higher accuracy, its regression coefficient R2 is as high as 0.98, and the characteristic importance score indicates that maximum crack width is the most influential factor. Comparison of the assessment results using this model with an earth dam earthquake damage assessment model based on an improved empirical statistical model showed further improvement in accuracy, which verified the reliability of the model in the application of rapid investigation and assessment of post-earthquake damage to reservoir dams.
Temporal and spatial evolution of layered subsidence in Hengshui City and its response mechanism to environmental factors
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240022
Abstract PDF icon114 icon2
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[Objective]Affected by climate change and human activities, the groundwater resources in Hengshui area are in an over-exploited state all year round, which directly leads to severe ground subsidence, which has become one of the main geological disaster problems in this region. [Methods]Based on the accumulated settlement data of the main urban area of Hengshui City from January 2009 to December 2022 obtained from layered monitoring, this paper analyzes and studies the ground subsidence mechanism of three compression layers (F1, F2, F3 layers from shallow to deep). Firstly, the Gompertz model is used to fit the cumulative settlement of each compression layer. The first-order derivative of the fitting results is obtained to obtain the settlement rate of each layer. With 0.5mm as the threshold, the settlement growth, rapid settlement rate growth, slow settlement rate decline and stable settlement period of each layer are obtained. Then, the zero growth (ZG) model is used to divide the settlement of each layer into irreversible settlement period (GRC) sequence and reversible rebound period (SWD) sequence, and analyze the fluctuation characteristics of settlement and rebound periods. Finally, the linear mixed model (LMM) is used to analyze the contribution of environmental factors such as precipitation, evapotranspiration, shallow groundwater level and deep groundwater level to the compression settlement (GRC_rate) during each layer's settlement period. [Result]The results show that: (1) The cumulative settlement fitting curves of each layer show an "S" shape, and the settlement rate curve shows a single peak pattern, with a "slow-fast-slow" trend. The main settlement period start time, end time, cumulative settlement and settlement rate of each layer are different; (2) In terms of cumulative settlement and monthly settlement increment amplitude, F3 layer＞F2 layer＞F1 layer. In terms of rebound amplitude, F1 layer＞F2, F3 layer; (3) Evapotranspiration and shallow groundwater level contribute most to the compression settlement of F1 and F2 layers, while shallow groundwater level and deep groundwater level contribute most to the compression settlement of F3 layer.
Rock Image Lithology Recognition Method Based on Lightweight Convolutional Neural Network
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240348
Abstract PDF icon116 icon10
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【Objective】Lithology identification is a crucial step in the process of oil and gas exploration and development, providing important guidance for exploration positioning, reservoir evaluation, and the establishment of reservoir models. However, traditional manual lithology identification methods are time-consuming and labor-intensive. Although classical deep learning models achieve high identification accuracy, they often have a large number of parameters. To enhance model accuracy while reducing the number of parameters, the aim is to make the model suitable for real-time lithology identification.【Methods】This paper first collected a dataset of 3,016 rock images consisting of eight types, including dolomite and sandstone. Based on the lightweight convolutional neural network ShuffleNetV2, the paper proposes a Rock-ShuffleNetV2 lithology identification model (hereafter referred to as the RSHFNet model). The model incorporates the Convolutional Block Attention Module (CBAM) and Multi-Scale Feature Fusion Module (MSF) into the base network to enhance feature extraction capabilities and improve identification performance. Additionally, the number of stacked ShuffleNetV2 units is optimized to reduce the model's parameters.【Results】The experimental results show that the RSHFNet model achieved an accuracy of 87.21%, which is a 4.98% improvement over the baseline model. Furthermore, the model's parameters and floating-point operations were reduced to 8.69 × 10^6 and 9.3 × 10^7, respectively, representing 67% and 63% of the baseline model. This reduction significantly decreases the model's size. Additionally, the RSHFNet model demonstrates superior overall performance compared to existing convolutional neural networks.【Conclusion】The proposed RSHFNet lithology identification model offers high recognition accuracy and strong generalization capabilities while being more lightweight, providing a new approach for real-time lithology identification in the field.
Genesis of the Naneng gold deposit in southeastern Yunnan: Evidence from in-situ trace elements and isotopes of sulfides
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240520
Abstract icon83
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[Objective] The Naneng gold deposit is an important medium-sized Carlin type gold deposit in southeastern Yunnan，and studying its genesis is of great significance for searching for such gold deposits in southeastern Yunnan. [Methods] Two generations of pyrite (PyI and PyII) were found to develop in the Naneng gold deposit during detailed field survey and indoor observation，and trace elements and sulfur isotopes of gold-bearing minerals are analyzed by LA-ICP-MS to constrain the source of ore-forming materials and ore genesis.[Results] LA-ICP-MS analyses show that PyI contains a small amount of Au (mean 6.37×10-6), which is relatively enriched in elements such as Co, Ni, Se, W; The distribution characteristics of trace elements in PyII and PyI are similar, but the content of Au (mean 68.02×10-6) is relatively high, and As, Sb, Cu elements are enriched in PyII; The average Au content of arsenopyrite is 36.02×10-6, and arsenopyrite is mainly enriched in elements such as As、Ni、Sb、Se、Au, while Zn, Ag, Hg and Tl elements are low. In addition, gold-bearing minerals in the Naneng gold deposit have consistent in situ δ34S values, ranging from 13.7‰ to 16.5‰, indicating that the S of gold-bearing minerals mainly come from the surrounding rocks.[Conclusion] It is preliminarily concluded that PyI was formed in a relatively stable environment by medium to low temperature hydrothermal fluid from the same source rich in trace elements such as Au、As、Sb, and a small amount of Au precipitated simultaneously with PyI in the form of solid solution (Au+). In the PyII stage, the intense tectonic activity in the area caused ore-forming fluid to upswell, and after sulfidation reaction with surrounding rock strata, the concentration of H2S in the fluid decreased, Au-HS complex became unstable, and Au supersaturated precipitation was enriched in PyII in the form of nanoscale inclusions (Au0).
Prediction model for rock elastic modulus based on TPE optimized ensemble learning
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240325
Abstract PDF icon79 icon3
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[Objective] Geophysical data is often used to determine the elastic modulus of formations in oil and gas engineering, with experimental data from small sample cores used for calibration. However, acquiring core samples from every stratum is impractical, which often leads to this method's inadequate performance in complex geological settings. To improve the predictive accuracy and generalizability of rock elastic modulus, an intelligent prediction model based on fundamental rock physical properties has been introduced. [Methods] Using 397 sets of core experimental data from diverse sources, with compressional wave velocity and shear wave velocity and density as input variables, intelligent prediction models for rock elastic modulus were developed based on three ensemble learning algorithms (RandomForest, XGBoost, LightGBM), the TPE method was employed to optimize the models. The dynamic elastic modulus and static elastic modulus regression model was constructed according to the methods currently used in petroleum engineering was used to provide a comprehensive assessment of the performance of the intelligent predictive model using statistical indicators. Additionally, the SHAP method was utilized to assess the contribution of each input variable to the model. [Results]The research findings indicate that: (1) The ensemble learning model optimized using TPE is significantly better than traditional statistical regression models, and can achieve accurate prediction of elastic modulus without distinguishing geological layers, with strong generalization ability. Among them, the XGBoost model performs the best (R2=0.87, RMSE=6.94，MAE=4.96）. (2) Shear wave velocity makes the greatest contribution to the model, followed by compressional wave velocity, with density having the least impact. Accurate shear wave velocity is crucial for predicting elastic modulus. [Conclusion] This method allows for the precise prediction of elastic modulus without the need for prior identification of the work area and strata, providing valuable insights for the design and implementation of oil and gas engineering projects.
In situ pH measurement and prediction modelling of the impure CO2-water system under high temperature and pressure conditions
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240421
Abstract PDF icon79 icon6
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[Objective] The injection of gases containing CO? into deep aquifers will dissolve to form carbonic acid, leading to a reduction in the pH value of the aquifer. This, in turn, will cause metal corrosion of pipelines and dissolution or precipitation of minerals, which will have an impact on the safety and efficacy of CO? geological utilisation and storage. The combination of experimental measurements of the pH of pure/impure CO? saturated solution systems with model predictions allows for the assessment of chemical changes under conditions of CO? geological sequestration. [Methods] In this study, the pH of pure CO?-water systems and impure CO?-water systems were measured under in situ conditions using potential and spectroscopic methods at temperatures between 35 and 93°C and pressures between 0.38 and 18 MPa. A chemical equilibrium model based on solubility calibration was then established to calculate and predict the pH values of pure/impure CO?–water systems for evaluation purposes. [Results] The findings indicate that N? and CH? exerts a detrimental impact on the CO?-saturated system, resulting in the reduction of CO? solubility in water and the subsequent elevation in pH. Notably, the influence exerted by CH? is more pronounced than N?. The model demonstrats superior performance in predicting the pH of the pure CO2-water system, with a maximum deviation of only 0.05 pH. However, in the impure CO2-water system, some deviation is observed, particularly at 50°C and a CO2-impurity gas ratio of 1:9, with a maximum deviation of 0.15 pH. [Conclusion] The findings of this study offer valuable insights into the chemical changes associated with impure CO2 injection into the formation, which is crucial for enhancing the safety and efficacy of carbon sequestration.
Sedimentary structure characteristics and logging identification method for the first member of Qingshankou Formation shale strata in Gulong sag
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240641
Abstract PDF icon87 icon9
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[Objective] The fine classification and quantitative characterization of sedimentary structure types is a crucial issue in the exploration and development of shale oil. [Methods] To this end, taking the continental shale strata of the first member of Qingshankou Formation (K2qn1) in Gulong sag of Songliao Basin as an example, based on core and thin section observations, whole-rock mineral X-ray diffraction and electrical imaging logging data, the sedimentary structure characteristics under lithological differences were clarified, and a quantitative logging identification method for sedimentary structures applicable to continental shale strata was established. [Results] The result shows that the differences in sedimentary structure characteristics under different lithologies of K2qn1 shale strata are mainly reflected in the mineral composition of the laminae and the thickness variation of the bedding (texture). The sedimentary structure types can be divided into laminar (single layer ≤1 cm), lamellar (1 cm < single layer < 10 cm), and massive (single layer ≥ 10 cm) based on the size of the single-layer thickness. Relying on the high resolution advantage of electrical imaging logging slice image, the layer interface in electrical imaging slice is identified by edge detection and Hough transform, and the sedimentary structure type is quantitatively divided based on the thickness of the layer interface. This method not only overcomes the problem of insufficient characterization accuracy of millimeter-scale laminae in traditional dynamic and static imaging logging images, but also compensates for the drawback that the previous use of laminae density cannot effectively divide the lamellar and laminar sedimentary structures within the logging unit window length. [Conclusion] Overall, the sedimentary structure logging identification method based on electrical imaging slices proposed in this paper has high accuracy and good generalization, which can provide strong support for the subsequent continental shale reservoir effectiveness evaluation.
Quantitative characterization and simulation of soil moisture distribution in heterogeneous vadose zone
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240256
Abstract PDF icon81 icon4
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Abstract:：[Objective] The vadose zone, as a crucial linkage between vegetation and groundwater, plays a significant role in influencing groundwater ecological functions. Among the various factors, lithological structure stands out as one of the primary factors affecting groundwater ecological functions. In order to investigate how the lithological structure of the vadose zone influences soil moisture distribution, [Methods] laboratory experiments were conducted on layered heterogeneous soil columns to investigate water release and infiltration. The distribution patterns of water movement during soil moisture infiltration, particularly the formation mechanism and distribution of capillary fringe above the fine-grained soil layer, were analyzed. Additionally, a comparative analysis was performed on the coupling of three commonly used Soil Water Characteristic Curve (SWCC) models with the Richards model. Based on this analysis, modifications were made to the simulation methods to better simulate water distribution in layered heterogeneous soils. [Results] During the experiment, the fine-grained soil interlayer structure causes water retention in the interlayer and at the upper and lower interfaces of the interlayer, forming a water accumulation area. Compared with column O, the water release duration of column A, column B and column C increased by 290h, 500h and 780h, respectively, and the water holding capacity increased by 6.20cm, 7.90cm and 7.83cm, respectively. The water retention in the interlayer of column A, column B and column C and at the interlayer interface accounted for 24.50%, 33.09%, 45.77% and 3.19%, 5.01% and 11.38% of the total water retention, respectively. The numerical simulation results show that the modified van Genuchten model can better simulate the layered soil moisture profile. [Conclusion] Fine-grained soil interlayer has a significant retarding effect on the underwater migration characteristics of infiltration, and water is mainly retained inside the interlayer and at the upper and lower interfaces of the interlayer. The increase in the thickness and number of interlayers will lead to more water retention inside the interlayer and at the interlayer interface. The corresponding relative permeability equation is divided into three stages, which can effectively improve the simulation accuracy of layered soil water content profile.
Frontiers and Potential Directions of International Deep Earth Exploration
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240456
Abstract PDF icon153 icon22
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【Objective/Significance】Deep Earth exploration is a multidisciplinary and complex endeavor to understand the structure, dynamics and evolution of continents and their margins. It is in the common interest of human society to study the Earth's interior and gain a deeper understanding of how it works. Since the development of deep Earth exploration for half a century, many countries worldwide have carried out a series of programs, and have accumulated rich experience and achievements while making significant breakthroughs in technology and methods, which has important reference significance for deep Earth exploration in China.【Analysis/Discussion/Progress】This paper analyzes the technical means and achievements adopted by the representative deep Earth exploration programs in the United States, Europe, Australia since the 21st century, and summarizes the latest progress of these programs. 【Conclusion/Prospect】Six frontiers and key potential directions of deep Earth exploration were summarized, including seismic tomography for deep Earth structure detection, magnetotellurics for mineral resource exploration, GNSS monitoring for Earth's motion and state changes, coupled surface to deep Earth processes, advanced data processing, analysis and modeling capabilities, and open data sharing. It is expected to provide information support and references for “SinoProbe-Ⅱ” deep exploration program, “Earth CT” international cooperative research program, and National Science and Technology Major Projects of deep Earth and mineral resources exploration in China.
The identification of active landslides and analysis of deformation influencing factors in the Baihetan Reservoir area
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240351
Abstract PDF icon170 icon18
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Reservoir landslides are a common geological hazard in hydropower engineering construction. When landslides slide into the reservoir area, they may cause surges, river blockages, and even dam breaches, resulting in significant economic losses and casualties. Therefore, studying the deformation characteristics of reservoir landslides is crucial for efficient and timely identification and monitoring of early-stage landslides along the reservoir area. [Methods]In this paper, the Baihetan Reservoir area is taken as the study area. Based on Sentinel-1 radar images, broad-scale active landslide disaster identification and deformation information before and after the reservoir filling of landslides in the Baihetan Reservoir area are obtained using Stacking Interferometry Synthetic Aperture Radar (Stacking-InSAR) and Small Baseline Subset Interferometry Synthetic Aperture Radar (SBAS-InSAR) methods. Combined with Sentinel-2 images, Automated Water Extraction Index (AWEI) is used to extract reservoir water level data. One typical landslide with significant deformation of each type—ascending, descending, and pre-filling deformation—was selected to investigate the relationship between reservoir water level fluctuations, rainfall, and landslide deformation. [Results and Conclusion] The study concludes that: The method of extracting reservoir water level data using AWEI with Sentinel-2 imagery has shown good results in this study area. The average error between the extracted water level and the measured water level at the same time is 0.89 meters. This method has research value for areas lacking water level data.During the observation period, a total of 103 active landslides were detected in the Baihetan Reservoir area using both ascending and descending orbit images. Among these, 37 active landslides involved the front edge entering the water, and 23 landslides were deformed due to water level fluctuations. There is a strong correlation between reservoir bank landslide deformation and water level fluctuations, while the correlation with rainfall is weaker, and the decrease in water level has a greater impact on reservoir bank landslide deformation.
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240208
Abstract PDF icon104 icon16
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Application of machine learning models to geothermal groundwater temperature prediction
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240063
Abstract PDF icon197 icon22
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Geothermal energy as a kind of clean energy has broad application prospects. The temperature assessment of geothermal water in sustainable development and utilization of geothermal resources is an important research topic. Artificial intelligence technology has become a hot spot and frontier direction in the exploration and development of mineral and oil and gas fields, but in the field of geothermal field development, there are few relevant studies. This paper first analyzes the important value of large data and artificial intelligence application in oil and gas field development, and then introduces the application of artificial intelligence in geothermal field development at present. Taking Xianyang geothermal field in Shaanxi province as an example, the single well geothermal water temperature time series model was constructed by using long and short term memory neural network (LSTM) under the predestined production mode. Random forest and XGBoost algorithm were used to predict the groundwater temperature of multiple geothermal wells. The accuracy of the three models was above 95%, and the running speed is fast. The depth at the top of the water intake section is the primary influencing factor of geothermal water temperature in this area. The model verifies that the fault zone plays an important role in heat storage.The application of the example verifies the superiority of machine learning in solving complex problems in geothermal field development, and the reasonable application of artificial intelligence technology can provide more effective decision-making basis for the efficient development of geothermal field and scientific cost reduction, quality improvement and efficiency improvement.
A Study on Defining the Evolution Stage of Sealing Properties of Fault Zone Filling materials ——Taking the F3 Fault in K1d1 of Beier Depression as an Example
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240302
Abstract PDF icon60 icon3
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[Objective] The unreasonable division of the evolution stages of the sealing ability of fault zone filling materials makes it impossible to reasonably explain the differences in oil and gas distribution in different parts of fault traps. [Methods] To solve this problem, in this paper, a research method is established to evaluate and evolve the Closure Index and Cement Index for the fault zone filling material and underlying reservoir rock, and then to comprehensively determine the evolutionary stage of sealing for fault zone filling material by comparing the relative size of the the Closure Index and Cement Index between the fault zone filling materials and underlying reservoir rocks over time. [Results] The method was used to determine the evolutionary stage of sealing of the F3 fault zone filling material in K1d1 of Huhenuoren tectonic belt, Beier Depression, Hailar Basin. The results show that: the fault zone filling materials of the F3 fault in K1d1 are in the stage of non-Closure Sealing and non-Cement Sealing at the measurement points 2,4, 6, 9-11, which is not conducive to the accumulation and preservation of oil and gas in K1n2, resulting in no oil and gas display obtained during oil and gas drilling. The fault zone filling materials of the F3 fault in K1d1 at measurement points 1, 3, 5 are in the stage of Closure Sealing at present. However, due to their evolutionary stage of non-Closure Sealing and non-Cement Sealing during the critical period of reservoir formation, no oil and gas was obtained during oil and gas drilling too. The fault zone filling materials of the F3 fault in K1d1 at measurement points 7、8、12-15 are in the stage of Closure sealing and Cement Sealing, which is most conducive to the accumulation and preservation of oil and gas in K1n2. There are oil and gas accumulation at measurement points 7-8 and 12-15 from oil and gas drilling. [Conclusion] Therefore, the method of determining the evolution stage of fault zone filling material sealing ability is feasible, which is of great significance for determining the sealing ability and formation time of fault traps, and improving the efficiency of oil and gas exploration.
Development Status and Trend Analysis of Physical Simulation Experiments for Geological Hazards
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240454
Abstract PDF icon116 icon14
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[Significance] In the past 20 years, physical simulation experiments of geological hazards have developed rapidly, forming an interdisciplinary, widely applied, and rapidly updated development status. Analyzing the current status and trends of physical simulation experiments for geological hazards can help researchers in related fields grasp the industry's current situation, design experiments, develop equipment, and update technologies based on development trends, providing rich and reliable experimental and data for theoretical innovations in geological hazards. [Progress] The paper has conducted extensive research on literature related to physical simulation experiments of geological hazards, and summarized five significances of conducting physical simulation experiments of geological hazards. Then, the research status of the six technologies for geological hazard simulation experiments is analyzed. Model box and flume simulation technology have the characteristics of diverse combinations, low prices, easy installation, and simple operation, and are the most widely used physical simulation technologies for geological hazards. The base friction technology achieves coupling between the simulation model and the gravity field at a low cost, but simulation experiments can only be conducted on two-dimensional slope models. Shaking table and centrifuge simulation technology have high construction and usage costs, but due to their ability to provide vibration and gravity environments for the experimental process, these two technologies are still irreplaceable in geological hazard physics simulation experiments. In situ simulation technology has the drawbacks of long experimental cycles, difficult model production, high personnel input, low automation level, and poor repeatability, but it has significant advantages in avoiding scaling effects, boundary effects, and gravity distortion. [Conclusions and Prospect] The physical simulation experiments for geological hazards are developing towards complex scene construction, large-scale experiments, scientific material selection, and intelligent data collection. This puts higher requirements on experimental technology and economic costs, and there is an urgent need to create a favorable development environment for physical simulation experiments of geological hazards so that physical simulation technology can play a greater role in geological hazard research.
Susceptibility Evaluation of Debris Flows in Gansu Province Based on LA-GraphCAN
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240324
Abstract PDF icon135 icon24
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[Objective]The current research on the susceptibility of debris flow disasters has yet to address the limitations of geographic location relationships and spatial dependence. [Methods]This article constructs a debris flow dataset for Gansu Province with 10,198 sample points and proposes a susceptibility assessment method based on LA-GraphCAN. Initially, a nearest neighbor graph is built using KNN based on the cprojection coordinates of sample points. Secondly, GCN is used to efficiently aggregate local neighborhood information and extract key geographic and environmental features. Additionally, GAT is introduced to add a dynamic attention mechanism, enhancing the representation of features. Then ,validate the effectiveness of the proposed method, conduct comparative analyses from different perspectives, and finally, evaluate the susceptibility of debris flows in Gansu Province. [Results]The results indicate that LA-GraphCAN achieves accuracy, precision, recall, and F1 scores of 0.9441, 0.9287, 0.9375, and 0.9331, respectively, outperforming mainstream machine learning models such as Random Forests and CNN. Based on the evaluation of LA-GraphCAN, the number of historical debris flow disaster points in the highly susceptible areas of Gansu Province is 4055, accounting for 95% of the historical debris flow occurrences in Gansu Province, which is consistent with the distribution of historical disasters. [Conclusion]Both the performance evaluation and the susceptibility assessment results for Gansu Province indicate that the LA-GraphCAN method, which considers the spatial dependencies of debris flow disasters, yields superior results and is well-suited for debris flow susceptibility research.
Research progress on formation mechanism and reservoir control of Strike-slip Fault-karst oil reservoir
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240149
Abstract PDF icon175 icon35
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[Significance] Fault-karst reservoir is widely developed in most basins in China, and its resources are huge, which has become a new hot topic in the field of geography. However, due to the deep burial and difficult exploration of fault-karst reservoir, and it is urgent to form a consensus understanding of trap division, formation mechanism and development control factors. [Progress and Conclusions] Based on literature research, this paper deeply discusses the formation mechanism of fault-karst reservoir. Fault-karst reservoir is a kind of fracture-vuggy reservoir formed in carbonate strata by karstification under the influence of multi-stage tectonic activities. Firstly, the basic concept of Fault-karst reservoir is reviewed. It is pointed out that fault-karst reservoir has the characteristics of deep burial, strong heterogeneity and large difference of fluid properties, and the important role of strike-slip fault in hydrocarbon accumulation and migration is emphasized. Based on the analysis of geological data in Shunbei area and other areas of Tarim Basin, this paper reveals the trap types, formation mechanisms and reservoir-controlling factors of fault-karst reservoir. It is concluded that the segmentation of strike-slip faults, the activity of solution fluid and the timely emplacement of hydrocarbons are crucial to the development of fault-karst reservoir. What's more, the roles of atmospheric fresh water, hydrothermal fluids and hydrocarbon fluids in reservoir reconstruction are also discussed, and how they jointly affect the formation and distribution of Fault-karst reservoir. At last, the paper summarizes the reservoir-forming models of fault-karst reservoir. [Prospects] The discovery and understanding of fault-karst oil reservoir have opened up a new field and direction of oil and gas exploration.
Characteristics of Change in Annual Runoff Volume of Karez in the Turpan Basin in Recent 30 Years
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240094
Abstract PDF icon207 icon20
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Karez is an important water conservancy facility in the Turpan Basin.The purpose of this paper is to alleviate the decreasing status of karez , analysing the changing characteristics of annual runoff volume of karez in recent 30 years, which is of great significance for agricultural irrigation, cultural heritage preservation, tourism development and so on. Based on the discontinuous 13 years of annual runoff volume of karez in the study area for the period 1990—2022, as well as year-by-year the exploitation amount of electro-mechanical wells, and water supply from surface water sources, statistical analyses were performed using SPSS 20 software to interpolate missing measurements, and use the trend and mutation analyses to determine their change curves and mutation years. The results of the study indicate: between 1949 and 2023 the number of karez reduced from 1084 to 169,implying that an average of 16 karezs dried up or disappeared each year, while the flow rate declined from 16.11 m3/s to 3.6 m3/s. The correlation coefficients between the annual runoff volume of karez and the exploitation amount of electro-mechanical wells, the amount of water supplied by surface water sources, the irrigated area and precipitation were -0.890, -0.149, -0.660, and 0.764. Through the construction of a model of the relationship between the annual runoff volume of karez and the exploitation amount of electro-mechanical wells and the amount of water supply from surface water sources, and the average relative error between the measured value and the predicted value was 1.8%, which effectively solved the problem of missing data. In addition, the exploitation amount of electro-mechanical wells and the amount of water supplied by surface water sources as a whole showed a fluctuating upward trend, and the annual runoff volume of the karez increased and changed abruptly in 2006, the reasons for the sudden change might be related to the government's implementation of regulations for the protection of karez. Therefore,in view of the important cultural and engineering value of karez , make greater efforts in the future to protect it and promote the sustainable use of water resources and high-quality development in the Turpan Basin.
Characteristics of oil shale development and paleoenvironment restoration of Jurassic Yan’an Formation in southwestern Ordos Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240171
Abstract PDF icon205 icon22
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[Objective]There are many sets of oil shale associated with coal and non-associated oil shale in the Jurassic Yan’an formation in the southwest of Ordos Basin, but the study on the characteristics and sedimentary environment of oil shale in this area has been relatively lacking for a long time. [Methods]Based on the oil shale samples from wells in the study area, the industrial index, geochemistry characteristics and sedimentary paleoenvironment of oil shale were studied by low-temperature retorting, rock pyrolysis, major and trace elements measurement and gas chromatography. [Results]The oil shale in study area oil-bearing ratio is 3.8% ~ 6.7%, the ash is 49.46% ~ 75.58%, the total sulfur is 0.31% ~ 2.29%, and the calorific value is 11.95 kJ/g (average value). The logging curves show the characteristics of high gamma, high resistivity and low natural potential, which is obviously different from coal bed and mudstone. The main type of organic matter was II2. The abundance of organic matter is high, and the whole is in the stage of immature-low maturity. It belongs to middle quality, siliceous ash and extra low sulfur oil shale. The main elements in the oil shale are SiO2 and Al2O3, which are 48.26% (average) and 17.57% (average) and the micronutrient Sr, Th, and U were enriched, and Ni, V, and Ba were depleted, indicating that there were more potassium-containing minerals and higher stable components in the study area. [Conclusion]Based on the analysis of paleoenvironmental element markers and saturated hydrocarbon chromatography, it is considered that the organic matter mainly comes from the mixed organic matter, ancient productivity is medium and the sedimentary environment is unique, which belongs to the warm and humid continental fresh water depression environment. The analysis of environmental factors shows that the redox condition is the main influencing factor of organic matter enrichment and the sedimentary model of oil shale evolution in Yan’an formation in different depositional periods is established. The research results provide important theoretical guidance and technical support for the oil shale exploration and development of the Jurassic Yan’an formation in the southwestern margin of Ordos Basin.
Pressure evolution and weak low pressure genesis of Shanxi Formation sandstone reservoir in Xinzhao area, northern Ordos Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240130
Abstract PDF icon83 icon15
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The Upper Paleozoic sandstone reservoirs in Xinzhao area, northern Ordos Basin are rich in natural gas and generally develop abnormal low pressure. The understanding of paleo-pressure evolution and current subnormal pressure formation mechanism is not very clear, which constraine the understanding of tight sandstone gas accumulation and increase of natural gas reservoir and production. In this paper, the petroleum charging history in the second member of Shanxi Formation was comprehensively analyzed by means of fluid inclusion petrographic observation, micrometry and laser Raman analysis, and the paleo-pressure in the key period of reservoir formation was obtained. The paleo-pressure evolution history was recovered by basin simulation method, and the coupling relationship between paleo-fluid pressure evolution and petroleum charging was established. The relationship between the causes of subnormal pressure and tight gas accumulation is further discussed. The results show that: (1) CO2 was captured in the second member of Shanxi Formation in Xinzhao area from 170 to 180Ma, when the source rock was in the middle to low maturity stage, and the methane inclusion was captured in the peak of hydrocarbon generation from 138 to 121Ma. (2) The overpressure in the second member of Shanxi Formation began to develop in the early Jurassic, and reached the maximum in the end of the Early Cretaceous. The paleo-pressure and paleo-pressure coefficient were about 50MPa and 1.31 respectively. (3) Due to temperature decrease, pore rebound and gas diffusion, the decrease of formation pressure in the second member of Shanxi Formation accounted for 49%, 14.5% and 36.5% of the total formation pressure, respectively. The tight gas reservoir of the second member in Shanxi Formation has undergone the evolution process of normal pressure-medium overpressure-normal pressure and low pressure. Hydrocarbon generation supercharging and pressure conduction are the main reasons for the formation of ancient overpressure. Temperature drop and natural gas diffusion are the main factors for the formation of abnormal low pressure in the second member of Shanxi Formation.
Provenance Analysis of Benxi Formation in Yanchang Exploration Area of Ordos Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240191
Abstract PDF icon105 icon15
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The source of detrital material is one of the important factors controlling the development and distribution of the Benxi Formation sandstone reservoir in the Yanchang exploration area. On the basis of previous research, this article conducted four methods for the source analysis of the Benxi Formation, including detrital zircon age, heavy mineral combination types, trace elements, and sandstone gravel size statistical analysis, on sand and mudstone samples from 37 wells in the Yanchang exploration area. The peak ages of 1912 Ma and 2425 Ma in the exploration area correspond to the northern edge of the North China Craton, while the peak ages of 435-447 Ma and 952-976 Ma in the remaining five wells correspond to the peak ages of the North Qinling Mountains. Based on this, the sources in the exploration area can be divided into two directions: north and south; In the analysis of heavy mineral combination types, the southwest region has a higher content of zircon and tourmaline, while the southeast region has a higher content of rutile. Therefore, the southern source can be further divided into two directions: southwest and southeast; Corresponding to the analysis results of heavy minerals, in the analysis of trace element zirconium niobium ratio, there are two directions of material sources in the southwest Longdong region and the southeast Yuxi region; Finally, by analyzing the distribution characteristics of sandstone gravel diameter on the plane, it is shown that there are sources from the southeast direction in the study area. Through comprehensive analysis, it can be concluded that the Benxi Formation in the Yanchang exploration area can be generally divided into three source areas: northeast, southwest, and southeast, indicating the erosion areas in the northern margin of the basin, the southern margin of the Qilian Mountains, and the eastern section of the North Qinling Mountains. Among them, the southeast source area is the thickest and closest to the Yanchang exploration area. This achievement has identified three directions of material sources and their influencing areas within the study area, which has important reference significance for predicting the distribution of sand bodies and dividing sedimentary facies in the Yanchang Benxi Formation gas field.
Simulation Research on the Formation Mechanism of Hydrochemistry in the Beishan Preselected Area for Geological Disposal of High-level Radioactive Waste in China
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240194
Abstract PDF icon153 icon21
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Hydrochemical characteristics play a pivotal role in the site selection and long-term safety assessment of high-level radioactive waste (HLW) disposal repositories. This study utilized integrated hydrogeochemical analysis and modeling to examine the general hydrochemical characteristics, horizontal zoning, and formation mechanisms of hydrochemical characteristics in different hydrogeological zones of the Beishan area in Gansu, China, considering it as a preliminary site for HLW disposal. The results indicated that the predominant hydrochemical types were Cl·SO4-Na and SO4·Cl-Na, with pH values mostly ranging from 7.5 to 8.3. The bedrock groundwater was generally undersaturated with respect to minerals such as halite, gypsum, fluorite, glauconite, and feldspar, while it was often oversaturated with respect to clay minerals. There was a clear horizontal zonation of hydrochemical characteristics from the recharge area to the discharge area. Mazongshan site was the main regional recharge area with low mineralization, where the formation of hydrochemical components was primarily controlled by leaching processes. Sedimentary basins were the discharge areas with high mineralization, where hydrochemical components were mainly influenced by evaporation. The water–rock interaction processes along the flow path were mainly driven by the dissolution of halite and gypsum, with minimal impact on silicates. Overall, the hydrochemical formation of bedrock groundwater in the Beishan area was predominantly governed by evaporation and interaction processes. This research provides important support on hydrochemistry for the site selection of the HLW disposal repository.
The characteristics、disaster mechanism、prevention and treatment and enlightenment of airport high fill landslide in mountainous area—Take Panzhihua Airport as an example
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240216
Abstract PDF icon206 icon22
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With the rapid development of China's transportation industry, numerous regional airports have been constructed in mountainous regions across the country. Due to the special engineering geological environment conditions, a large number of high fill slope projects have been produced, and the biggest problem faced by them is the deformation control and long-term stability of high fill slope in the operation stage. Taking Panzhihua Airport as an example, based on the systematic review of the geological disaster history during the construction period and operation period, the development characteristics of three typical high-fill landslides during the operation period were described in detail, and the causes and evolution mechanism of high-fill landslides were analyzed. Finally, the key technology of landslide control was proposed. The results show that: (1) The internal causes are the topography and landform that is conducive to the accumulation of surface water and the special slope body structure that is conducive to rainfall infiltration. Rainfall concentration and short-time rainstorm are frequent, and the groundwater is abundant and easy to be enriched in the relative water barrier layer;(2) The instability evolution mechanism of the high fill slope of Panzhihua Airport can be summarized as follows: long-term infiltration of heavy rainfall - rise of groundwater - softening of soil on the weak surface of foundation cover section and attenuation of shear strength - push creep - failure of retaining structure - progressive slip shear - overall slide; (3) This kind of high fill landslide should be treated with the idea of anti-sliding strong support and retaining combined with drainage groundwater. The research results can be used as reference for the research of deformation mechanism and deformation control technology of other high fill projects.
Optimization of 4D Hydrogeological Processes Monitoring Through Cross-hole Electrical Resistivity Tomography (CHERT) using Bayesian experimental design
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230600
Abstract PDF icon234 icon26
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(Objective) The geophysical method can effectively monitor the dynamics of water flow and material transport in 4-D hydrogeological processes, and its imaging accuracy is often closely related to the monitoring scheme. Taking the commonly used Electrical resistivity tomography (ERT) as an example, in order to obtain good imaging accuracy, a large number of electrode arrangements are often required, which leads to a long monitoring time and therefore cannot timely respond to the 4-D hydrogeological dynamic process. Most of the existing ERT monitoring scheme optimization studies focus on surface ERT, and few focus on cross-hole ERT. (Methods) Since cross-hole ERT has more advantages in the high-precision characterization of the study area, this study proposed to optimize the monitoring scheme of cross-hole ERT by Bayesian experimental design. By comparing the measurement time and accuracy of the optimized electrode arrangement with the traditional electrode arrangement through indoor static/dynamic tests and field sites, the validity of the optimization scheme of Bayesian experimental design was verified. (Results) The laboratory test results showed that the optimized monitoring scheme could reduce the measurement time by about 75%, and the inversion results of the optimized scheme could more accurately depict the dynamic resistance anomaly region, significantly improving the hysteresis error of the traditional scheme monitoring the 4-D hydrogeological process. Field test shows that the optimized scheme can reduce about 95% monitoring time under the premise of ensuring monitoring accuracy. (Conclusion) Optimizing the monitoring scheme of cross-hole ERT electrode arrangement based on Bayes experiment design provides technical support for efficient monitoring of 4-D hydrogeological processes.
Discussion on the spatial and temporal difference of Cenozoic rift formation and evolution and its genesis mechanism in the Pearl River Estuary Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240054
Abstract PDF icon164 icon25
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To deepen the understanding of the temporal and spatial differences. In the this study is based on the seismic profile data of the the Pearl River Mouth Basin, using the methods of structural analysis, balanced profilerestoration and fault activity rate calculation, the fault system and structural evolution process of the the Pearl River Mouth Basin are analyzed. Moreover, the. causes of structural differences in the depressions in this Basin are explored in combination with the pre-existing structure, basement characteristics and dynamic background of the basin. The main results are as follows: The basement pre-existing structures in the Pearl River Mouth Basin mainly developed a series of NE trending thrust faults and the conjugate NW trending pre-existing thrust fault system; The faults in the Pearl River Mouth Basin show NE, NEE, near EW and NWW strike from west to east, controlling the tectonic framework of the basin during the rifting period; The evolution stages of the basin are divided into four stages: the early stage of rift (E1sh-E2w), the development stage of rift (E3e), the depression stage (E3z-N1z-N1h), and the tectonic activation stage (N1y-N2w-Q); The fault system in the basin mainly exhibits a clockwise transition from NE-NEE extensional properties to nearly EW-NW extensional strike slip properties. This is due to the long-term inheritance and development of some main faults along the basement pre-existing faults during the rift period. At the same time, the differences in basement pre-existing structures and lithology result in different tensile and shear strengths, as well as being controlled by peripheral plate movement, magmatism, and regional stress field changes. The rift structure of the basin has undergone a transformation from north to south, from narrow and narrow grabens and semi grabens with "thick below and thin above" characteristics to wide and gentle grabens and semi grabens with "thick above and thin below" characteristics. The distribution of sedimentary centers in the basin shows a migration pattern along the NE direction.
Geochemical analysis of Ordovician natural gas in Shunbei area of Tarim Basin and its exploration significance of oil and gas
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240099
Abstract PDF icon172 icon24
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After years of exploration, oil and gas breakthroughs have been made in the strike-slip fault zones in the northeast of Shunbei area, forming hydrocarbon types and phase distribution patterns characterized by oil reservoirs in the north, condensate gas reservoirs in the south, and dry gas reservoirs in the east. Therefore, it is of great significance to discuss the genesis mechanism, source and thermal maturation of the gas from the perspective of the overall oil and gas distribution for the further continuous promotion of ultra-deep oil and gas exploration. By systematically collecting gas samples from different fault zones, this study analyzes the geochemical characteristics of natural gas in Shunbei area in detail. The results show that the natural gas in Shunbei area is less affected by TSR, except that there is strong modification by thermal-chemical sulfate reduction (TSR) in the part locations of the fault zones. The natural gases in the No. 1 fault zone and in the northern and middle sections of the No. 5 fault zone are mainly the crude oil associated gas from the primary kerogen cracking, while the natural gases in the southern section of No. 5 fault zone and No. 4 fault zone are mainly the mixture of early kerogen cracking gas (oil-associated gas) and late crude oil cracking gas. The natural gas in Shunbei No. 12 fault zone originated from deeper high-temperature crude oil cracking gas, and the crude oil cracking grade has reached wet gas cracking. The natural gases in the study area mainly comes from the source rocks of the Lower Cambrian Yurtus Formation, and the parent material of gases has the characteristics of benthic algae or mixed source of benthic algae and planktonic algae. Finally, the regression equation of thermal maturity calculation based on carbon isotope of methane is established during the process of hydrocarbon generation in the source rocks of Yurtus Formation. The research results can provide important reference for the next ultra-deep gas origin, source and thermal maturity analysis.
FDEM simulation study on deterioration characteristics of weak-hard interbedded strata landslide-anti-slide pile system under wetting-drying cycles
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230700
Abstract PDF icon177 icon29
Abstract:
[Objective]In Zigui Basin of the Three Gorges Reservoir region, prone-sliding strata mainly composed of weak-hard interbedded strata are widely distributed. Under the action of long-term reservoir water immersion, erosion and rainfall, the formation rock and soil bodies deteriorate and become an important internal cause of reducing landslide stability and affecting project safety. [Methods]Taking rock and soil mass of weak-hard interbedded strata as the research object, fi-nite discrete element method (FDEM) is used to calibrate the mechanical properties of hard and soft rocks in the weak-hard interbedded strata under different wetting-drying cycles. Then the mesh is redivided by the improved Tyson poly-gon program, and the embedding function of zero thickness cohesive force unit is realized. The FDEM numerical model of landslide-anti-slide pile system in weak-hard interbedded strata formation is proposed and established. Finally, the formation process of landslide cracks and the embedding mechanism of anti-slide piles under different wetting-drying cycles are studied. [Results]The results show that: ① The number of simulated landslide cracks increases with the in-crease of the number of wetting-drying cycles, and the cracks width also increases gradually. The results of simulation are basically consistent with those of the site of Majiagou landslide; ② The simulated cracks of the landslide-anti-slide pile system show two evolutionary patterns: one is that the cracks spread downward from the rock mass on the top side of the pile along the pile body; the other is that the cracks gradually extend from around the anti-slide pile to the inside of the slide body, connecting with the transverse cracks and vertical cracks, and finally forming large through cracks; ③ When the number of wetting-drying cycles increases, the horizontal displacement, bending moment and shear force of anti-slide pile also increase; ④ The cracks in the weak-hard interbedded strata bedrock of the anti-slide pile have the characteristics of localized development, and with the increase of the number of wetting-drying cycles, the stress in the region gradually decreases, the displacement and strain gradually increase, and the corresponding cracks become more and more intensive. [Conclusion]The results of this study can provide support for the prevention and control of land-slide in weak-hard interbedded strata under different wetting-drying cycles.
Susceptibility evaluation of debris flow in Bomi-Metuo area based on Pearson Chi-square test algorithm
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240091
Abstract PDF icon209 icon18
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The complex geomorphic units and active geological structures in Tibet provide a good breeding environment for debris flow in the region, but also pose a great threat to human life and property. The evaluation of debris flow susceptibility can identify key areas for disaster prevention and reduction in the region. Taking Bhumi County and Medog County of Tibet Autonomous Region as the study area, 12 factors with high influence on debris flow, including elevation, slope, stratigraphic lithology and rainfall, were selected by Pearson Chi-square test algorithm as evaluation indexes, and 282 debris flow points and non-debris flow points in the study area were taken as sample database. Based on ArcGIS platform, four susceptibility evaluation models were established by using information method and machine learning method, and ROC curve and AUC index were introduced to evaluate the susceptibility accuracy of debris flow. The results show that: (1) Considering the different types of debris flow in different dimensions and the different controlling factors, the normalization coefficient of latitude and air temperature is used as the evaluation index of debris flow susceptibility, which can eliminate the excessive response of debris flow to temperature in low altitude areas to a certain extent. (2) Air temperature, distance from water system, distance from road, formation lithology and elevation are the main factors of debris flow occurrence in the study area; Factors such as vegetation coverage, terrain humidity, and slope also play an important role. (3) Considering the relationship between the disaster point of debris flow and the classification attributes of the impact factors, the classification attributes of the impact factors were assigned scores and trained as input features. The prediction effect of the machine learning model was good, and the average AUC was 0.980, which was better than the traditional information model on the whole. (4) The AUC of SVM model is as high as 0.987, the FR value of the highly prone region is 41.13, and the prediction area of highly prone regions takes up the smallest proportion, so it has the ability to perform high-precision prediction in large-scale regions.
Experimental Study on Dynamic Impact Compression Characteristics of Sandstone under Freeze-thaw Cycles
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240103
Abstract PDF icon160 icon13
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In order to study the effect of freeze-thaw cycles on the microstructure and dynamic mechanical properties of sandstone, nuclear magnetic resonance testing, electron microscope scanning and dynamic impact compression tests with impact velocities of 3, 6 and 9 m/s were carried out on sandstone with freeze-thaw cycles of 0, 30, 60, 90 and 120 times, respectively. The results show that the dynamic mechanical properties of sandstone deteriorate with the increase of freeze-thaw cycles at the same impact velocity. All dynamic mechanical properties have rate-dependent effects. In addition, the dynamic peak stress index attenuation model of freeze-thaw sandstone is established, and it is proved that the impact velocity can compensate the damage and deterioration of freeze-thaw cycle to a certain extent, which can reduce the attenuation constant and prolong the half-life of freeze-thaw sandstone. The dynamic impact failure mode of freeze-thaw sandstone is as a whole crushing failure. With the increase of freeze-thaw cycles and impact velocity, the fragmentation degree of sandstone increases, the fragment scale decreases, the fragment quantity and powder proportion increase, and the fractal dimension increases. Based on the above tests, the damage mechanism of sandstone under the action of freeze-thaw cycle is explored, and it is found that frost heave damage is the main cause of freeze-thaw damage of sandstone. With the increase of freeze-thaw cycles, the internal damage degree of sandstone intensifies, the bonding effect between mineral crystals and cementing materials weakens, the pore size and number increase, and even intergranular cracks and transgranular cracks appear. This study can provide relevant reference for rock engineering in cold area
Identification and saturation calculation of hydrate bearing gas layer in ultra-shallow loose sandstone in deep water
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240082
Abstract PDF icon198 icon19
Abstract:
In the process of marine gas hydrate exploration, the electrical response characteristics of hydrate-bearing gas layers are extremely complex, which leads to great difficulties in the qualitative identification and quantitative evaluation of hydrate-bearing gas layers. Therefore, based on the logging response characteristics of deep-water ultra-shallow loose sandstone hydrate gas reservoirs in the South China Sea, combined with qualitative identification methods such as porosity difference method, neutron-density curve overlapping method, shear modulus method, etc., the saturation of hydrate gas layers was identified and the method of inverting longitudinal wave velocity and resistivity at the same time to find the minimum joint error was used to solve the saturation of hydrate gas layers. The results show that the method of joint inversion of acoustic wave and resistivity logging to calculate the saturation of hydrate gas layer is feasible and reliable, and the hydrate saturation and shallow gas saturation can be calculated at the same time, the calculation results of the joint inversion of Well Z in block L are in agreement with the core saturation of 81.25%, and the joint inversion results of Well Y in block L are in agreement with the calculation results of hydrate or shallow gas calculation model alone by nearly 85%, which can provide a reference for the identification of hydrate gas layers and the calculation of saturation in the field.
International Research Progress and Development Suggestions of Hot Dry Rock EGS System Flow Test
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230644
Abstract PDF icon162 icon39
Abstract:
Hot dry rock is a widely distributed and abundant geothermal resource. Its development and utilization are of great significance for reducing fossil energy consumption, alleviating environmental pollution and ensuring energy security. The enhanced geothermal system is the main way to develop dry hot rock at present, which is generally implemented through several links such as project site selection, geothermal drilling, thermal storage construction, flow test and commissioning power generation. Among them, the cycle test is an important link to undertake the construction of thermal storage and power generation engineering, which is used to form injection-production well groups, evaluate the cycle circuit, expand the heat exchange capacity, and lay the foundation for the final safe and stable realization of power generation objectives. The implementation process of the flow test is characterized by long-term and complexity, which is easy to cause problems such as insufficient connectivity, strong microseism, liquid leakage, scaling of the circulating fluid, and insufficient equipment reliability. Therefore, the flow test construction of dry-hot rock development sites in the world is often interspersed with drilling and reservoir reconstruction, and accompanied by scheme adjustment, to gradually achieve the goal of power generation. This paper briefly summarizes the flow test experience of developing EGS system for typical dry hot rock at home and abroad, expounds the influence of various factors on flow test, and puts forward development suggestions based on the actual situation of the site in Qinghai Republic, providing reference for technical personnel engaged in relevant fields.
Fine-grained Identification of Internal Characteristic Zones within the Strike-slip Fault Using the XGBoost Algorithm
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230583
Abstract PDF icon143 icon23
Abstract:
Constrained by the strong heterogeneity within the internal structure of the strike-slip fault, the variability of reservoir spaces, and the complex distribution of fluids, the logging responses among the three characteristic zones within the strike-slip fault—namely, the fracture zone, fractured zone, and dissolution zone—are highly complex and variable. This complexity poses challenges for the effective utilization of imaging and conventional logging data to identify these three internal characteristic zones within the strike-slip fault.An analysis of the logging response characteristics of the "three zones" within the internal structure of the strike-slip fault was conducted. Sensitive logging curves were selected to construct a feature vector space based on mean and variance. The Extreme Gradient Boosting (XGBoost) algorithm was employed to establish XGBoost regression prediction models for the dissolution zone, fractured zone, and fracture zone within the strike-slip fault. Key parameters of the XGBoost model were optimized using multi-class evaluation metrics, resulting in an improved accuracy of identifying the "three zones" within the internal structure of the strike-slip fault.Utilizing the constructed XGBoost model, the identification of the "three zones" within the strike-slip fault in the study area achieved an accuracy rate of 88.89%. This indicates that the XGBoost-based identification model for the internal characteristic zones within the strike-slip fault can effectively distinguish the fracture zone, fractured zone, and dissolution zone. It holds valuable implications for a fine-grained characterization of the internal structure of the strike-slip fault.
Automatic Detection of Effective Microseismic Events Based on U-Net Neural Network
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230689
Abstract PDF icon156 icon26
Abstract:
Abstract: [Objective]Automatic pickup of effective events is an important part of microseismic monitoring, and the accuracy of pickup directly affects the accuracy and reliability of subsequent seismic source localization and seismic source mechanism inversion. [Methods] In this paper, a 10-layer U-Net neural network model framework is constructed, the original microseismic data from 3D finite-difference simulation and the raw microseismic data from the measured gas storage reservoirs are made into labeled images, which are cut into 128*128 sized slices and input into the U-Net neural network for learning, and then the output of predicted slices is outputted and merged, and then the predicted images are binarized, and the microseismic effective events are extracted in the end of the P-wave first arrivals. This makes the edge segmentation of background noise and effective signal image more fine, and improves the efficiency and accuracy of automatic picking up of effective microseismic events.[Results]Quantitatively analyze and compare the pickup rate, wrong pickup rate and pickup error of U-Net method and STA/LTA method, the test results show that the pickup effect of U-Net is better than that of STA/LTA method, and U-Net also has a strong anti-jamming ability and generalization ability; Evaluate the effect of different label widths on the first-to-pickup results, the results show that the label pickup effect based on the event's primary cycle is The results show that the label pickup effect based on the main cycle of the event is the best.[Conclusion] The U-Net neural network first-to-automatic pickup algorithm established in this paper is an important part of the highly efficient and high-precision reservoir integrity microseismic intelligent monitoring system, which is of great significance to improve the level of microseismic monitoring technology in China.
The most dangerous sliding surface of the three-dimensional slope of the open-pit mine was generated based on multiple profiles
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230690
Abstract PDF icon163 icon20
Abstract:
At present, the two-dimensional profile is widely used for slope stability analysis, which can efficiently and accurately evaluate the stability of the slope. However, the two-dimensional section cannot describe the three-dimensional spatial shape and three-dimensional sliding body of the most dangerous sliding surface of the slope. In order to solve this problem, based on the stability analysis of the two-dimensional section slope, the three-dimensional most dangerous sliding surface of the slope is fitted by using the spline function by associating multiple sections with the three-dimensional slope model. Firstly, the relationship between the two-dimensional profile and the three-dimensional slope space is established by setting the profile name, horizontal coordinate positioning and elevation positioning of the graphic elements in the profile line and the two-dimensional profile. Secondly, the most dangerous sliding surface lines of each section are automatically generated, and the most dangerous sliding surface lines of each two-dimensional section are converted to three-dimensional slope space by using the coordinate transformation formula. Finally, the spline function interpolation is used to fit the most dangerous slip surface lines in the three-dimensional space to construct the three-dimensional most dangerous slip surface. Taking the southwest slope of an open-pit mine in Xilinhot, Inner Mongolia as an example, a three-dimensional engineering geological model of the slope is established, and five two-dimensional profiles for slope stability analysis are generated. Through this method, the three-dimensional most dangerous sliding surface and three-dimensional sliding body of the slope are successfully generated.
Discussion on fine 3D modeling method of complex vein ore body
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20240050
Abstract PDF icon212 icon32
Abstract:
Abstract: 【objective】 The surface structure and internal physical properties of geological bodies are simulated by using 3D geological modeling technology, which provides a reliable basis for revealing the spatial distribution of geological resources, resource estimation and resource development, and is the core technology of the construction of "glass earth". It is also an important carrier of geological time and space big data. Since the 1990s, 3D geological modeling technology has been developed rapidly. Researchers proposed many different modeling methods, but there were still many problems in fine modeling of complex orebodies. Compared with the implicit modeling method, the explicit modeling method was more accurate in depicting small-scale geological structure features. However, for the large-scale fine 3D modeling of geological bodies such as complex vein orebodies, there were still some problems, such as low modeling accuracy and poor morphological expression of the model, so it is difficult to meet the needs of mine production and resource estimation at present. 【Methods】 In this paper, aiming at a series of complex geological phenomena of local vein orebody, such as bifurcation compound, non-ore skylight, rock entrapment, fault cutting and so on, the techniques of orebody split line, segmented modeling and orebody suture are comprehensively used to construct orebody split line, segmented modeling, orebody suture and so on. Four kinds of explicit 3D modeling methods of complex vein orebody, such as bifurcation composite orebody, non-ore skylight orebody, stone-bearing orebody and fault cutting orebody are studied systematically. Among them, the constraint point is generally located in the ore center and the outline of the orebody, and the complex part of the model needs to add constraint points to complete the constraint of the shape of the orebody. The splitting line is the connecting line between the cusp-out point at both ends of the boundary line of the orebody and the central point of the ore-seeing project. it is mainly used to split the complex vein orebody, and the split line is used to model the branch-bifurcated composite orebody according to the regional geological law. Segmented modeling is to model the complex parts of complex orebodies separately. The stitching of orebody is to assemble the segmented model along the strike to form a complete model. 【Results and conclusion】 Through the above technology and the explicit modeling method based on measured data, the high-precision and fast 3D modeling of complex vein orebody is realized, and the difficult problem of narrow, thin and complex vein orebody modeling is solved effectively. The 3D modeling process of different complex vein orebodies is improved, and the orebody model is displayed in 3D space in multi-angle, and the most real geological shape of the orebody is reconstructed with the outline of the orebody. High-precision model will not only obtain detailed 3D information of orebody, but also will grasp the distribution law of orebody quickly and accurately. This modeling method is of great significance to the fine 3D modeling of rare and precious metal and other complex vein orebodies, the estimation of mineral resources and the formulation of mineral resources development and utilization plan, and will better guide the exploration and prospecting work.
Tracing of the sources of dissolved organic matter in coastal groundwater based on fluorescent indices and end-element mixing analysis
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230711
Abstract PDF icon278 icon46
Abstract:
Dissolved organic matter (DOM) in coastal groundwater is derived from multiple sources including marine water, river and leachate from sediments. Quantitative estimation of the contribution of difference sources to coastal groundwater is importing for understanding the carbon reactive transport in the coastal area. Isotopic tracer, fluorescent indices, and end-element mixing analysis (EMMA) were used to identify the sources of DOM in coastal groundwater and quantify their contributions. The results showed that DOM in coastal groundwater was mainly originated from DOM in river water, seawater and sediments, with contributions of 44.0% ± 22.2%、33.0% ± 10.8% and 22.9% ± 13.1%, respectively. Groundwater collected from the north part of study is affected by both seawater intrusion and fresh water recharge, showing a high proportion of seawater DOM and autogenous characteristics. In the south part, groundwater has higher total dissolved solids (TDS), saline water releases DOM in sediments, showing higher proportion of DOM in sediments and humification characteristics. This study demonstrates the DOM in coastal groundwater is affected by hydrodynamic and hydrogeological conditions. End-element mixing analysis based on fluorescent indices can efficiently quantify the sources of DOM in coastal groundwater, which provides a new perspective and assessment method for the study of terrestrial-oceanic carbon cycle.
Geochemistry, zircon U-Pb age and Lu-Hf isotope characteristics of in Daliuhang Mesozoic granites in Jiaodong area and their tectonic significance
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230693
Abstract PDF icon140 icon23
Abstract:
[Objective] To determine the Mesozoic granite type, age and tectonic setting and discuss the relationship between the granite and gold mineralization in Daliuhang, Jiaodong Peninsula. [Methods] In this study, the Mesozoic Yanshanian Linglong-type granites (Qijiagou monzonitic granite) and Gujialing-type granites (Gusidian monzonitic granite), which were located in the north of Qixia-Penglai gold metallogenic belt in eastern Jiaodong Peninsula. These samples are selected to analyze whole-rock geochemistry, U-Pb dating and Lu-Hf isotope study of zircon. [Results] The results show that the U-Pb age of the zircon from Qijiagou monzonite is 172.8±1.5 Ma, and the εHf(t) value of the zircon is -27.7 ~ -20.3. The zircon U-Pb age of Gusidian monzonitic granite is 127.3±0.8 Ma, the εHf(t) value of zircon is -15.7 ~ -13.4. The 87Sr/86Sr ratio of Gusidian monzonitic granite is 0.710937 ~ 0.712735, and the εNd (t) range is -16.8 ~ -11.3. [Conclusion] The source of Qijiagou monzonitic granite is ancient lower crust, which is mainly from the North China Craton lower crust. The magma source of Qijiagou monzonitic granite may be mixed with the Yangtze craton crust. Gusidian monzonitic granite is formed by partial melting of mafic rocks of lower crust, which added mantle components in the process. The diagenetic tectonic background of Gusidian magma formation is extensional, which may be caused by the subduction and retreatment of the Pacific plate. The Gusidian monzonitic granites have high coordination with the characteristics of early Cretaceous gold mineralization in Jiaodong Peninsula, suggesting that Gusidian monzonitic granite may be related to gold mineralization in this area.
Orbital cycle recognition and sequence stratigraphic division of the Lower Carboniferous Dawuba Formation shales in Southwest Guizhou
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230546
Abstract PDF icon210 icon23
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【Objective】The Lower Carboniferous Dawuba Formation in southwest Guizhou has developed a set of shale with great exploration potential. However, the scheme of sequence stratigraphic division is not unitive and the understanding of sequence development mechanism is unclear, which restricts the promotion of unconventional oil and gas exploration. Therefore, this paper carries out cyclostratigraphic analysis and sequence stratigraphy research on this set of shale stratum, aiming to realize the "quantitative" stratigraphic division of shale from the perspective of orbital cycles.【Methods】The Well QSD-1 (1457-2466 m) was selected as the research object, and the gamma ray logging curve was used as the proxy index, the cyclostratigraphic analysis and sequence stratigraphy were carried out by using time series analysis, INPEFA analysis and wavelet analysis.【Results】Obvious orbital cycles have been recognized of the Lower Carboniferous Dawuba Formation shales in Southwest Guizhou. The optimal sedimentation rate of the stratum was estimated by COCO is 16.4 cm/ka, and the matching sedimentation thickness of 66.42 m represents the long eccentricity cycle of 405 ka. Spectral analysis was conducted again for GR series (1457-1932 m and 1932-2466 m) of Well QSD-1, and the optimal sedimentation rate was estimated to be 16.5 cm/ka in the upper section and 11.2 cm/ka in the lower section. The filtering results show that 19 long eccentricity cycles are recorded in Dawuba Formation. The "floating" astronomical time scale of Dawuba Formation is established, and the duration of Dawuba Formation is estimated to be about 7.86Ma. The relative sea level change curve of Dawuba Formation is restored by establishing the sedimentary noise model (DYNOT and ρ1) of the research interval. Based on the age framework established by the cyclostratigraphic research, according to the extreme value of the relative sea level change curve, combined with the results of INPEFA analysis and wavelet analysis, the third-level sequence boundary and the maximum flooding surface of Well QSD-1 were recognized. Six third-order sequence boundaries and five third-order sequences were recognized in Well QSD-1 Dawuba Formation, and the development of third-order sequences were correlated by obliquity amplitude modulation (AM) cycle (~1.2 Ma). 【Conclusion】The research method of cyclostratigraphy is applied to the stratigraphic division of Lower Carboniferous Dawuba Formation shale in southwest Guizhou, and the relationship between astronomical orbit parameters and relative sea level changes at different time scales is discussed, and the third and fourth order stratigraphy are divided. Cyclostratigraphic provides the possibility for the correlation of marine shales on the ten thousand years time scale, provides a fine age framework for the prediction of high-quality source rock development intervals in shale oil and gas exploration, and provides theoretical guidance for oil and gas exploration in shale.
Research on information extraction method of dangerous rock mass on high and steep slopes based on multi-source remote sensing data fusion
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230695
Abstract PDF icon257 icon47
Abstract:
Abstract:[Objective]There are a large number of high and steep slopes in mountainous areas in my country. Due to their hidden and dangerous characteristics, it is currently difficult to accurately obtain the distribution location and characteristic information of rock masses on high and steep slopes through manual surveys and single non-contact measurements. [Methods]This paper fuses point cloud data obtained from airborne LiDAR, ground LiDAR and UAV oblique photogrammetry with multi-source data to complement each other's advantages. The fused point cloud is then used to analyze high and steep slope hazards. Extract information from the scale boundary, trailing edge characteristics, occurrence information and structural plane characteristic parameters of the rock. [Results]The results show that the multi-source data fusion method used in this article effectively complements the advantages of various data. The fused point cloud is used to extract scale boundary, trailing edge information and structural plane characteristic parameter information of dangerous rocks on high and steep slopes. The extraction accuracy meets [Conclusion]The relevant specification requirements provide a technical method for the refined extraction of geometric parameter information of rock mass on high and steep slopes in mountainous areas.
Reservoir characteristics and development control factors of Benxi Formation bauxite in Linxing area of Ordos Basin
, Available online  , doi: 10.19509/j.cnki.dzkq.tb20230657
Abstract PDF icon269 icon47
Abstract:
In recent years, the bauxite gas exploration of Taiyuan Formation in Longdong area of Ordos Basin has made a major breakthrough, which has attracted wide attention at home and abroad. In the same period, the bauxite rock gas of Benxi Formation in Linxing area has also made some progress, but the characteristics and controlling factors of bauxite reservoir in this area are unclear, which restrict the exploration process. [Objective]In order to identify the reservoir characteristics and control factors of Benxi Formation bauxite in Linxing area, [Methods]The paper carried out XRD, casting sheet image, SEM-EDS, mercury intrusion porosimetry, nitrogen adsorption, carbon dioxide adsorption, routine porosity detection and other analysis methods. The mineral composition, pore structure and physical properties of the bauxite reservoir are characterized, and the controlling factors of the development of the bauxite reservoir are discussed based on seismic logging data. [Conclusion]The results show that the aluminum-bearing minerals in the bauxite of Benxi Formation in Linxing area are mainly diaspore, and the pore types are mainly intra granular pores, intergranular pores, matrix pores, intergranular pores and micro-cracks, and occasionally organic pores. In addition, the pore volume of bauxite rocks is mainly provided by mesoporous and macroporous pores, and the distribution range of pore peaks is mainly 30-70 nm, 80-130 nm and 4-13 μm. Thirdly, the physical property conditions of the bauxite reservoir are general, with an average porosity of 3.28% and an average permeability of 1.398×10-3 μm2, but the upper section with higher content of diaspore at the bottom still has better physical property conditions. Finally, the development of bauxite reservoir in Linxing area is controlled by palaeo-geomorphology, palaeo-sedimentary environment and diagenesis. Among them, The accumulation and distribution of bauxite are controlled by the paleogeomorphology of depressions and troughs and the enclosed and semi-enclosed intermittent swamps and lagoons sedimentary environment, while diagenesis controls the reservoir space type and physical property conditions of bauxite reservoirs based on the sedimentary environment.

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