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）

2020 Vol. 39, No. 6

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2020, 39(6)
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Cenozoic fault characteristics and petroleum geological significance in Banqiao slope area of Qikou Depression
Han Guomeng, Mou Liangang, Dong Yueqi, Fu Dongli, Zhou Suyan, Wu Jiapeng, Wang Jincheng
2020, 39(6): 1-9. doi: 10.19509/j.cnki.dzkq.2020.0603
Abstract FullText HTML PDF icon1273 icon3611
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Qikou Depression has developed many types of slope structures, which are the main enrichment areas of stratigraphic and lithologic reservoirs.Banqiao slope is a rotating tilting slope controlled by boundary faults in the western margin of Qikou Depression, and its fracture characteristics are complex.Based on the three-dimensional interpretation of drilling and high resolution seismic data, this paper analyses the fracture characteristics in Banqiao slope area and discusses the geological significance of its petroleum.The results show that there are three different types of fault systems in Banqiao slope, and their combination types, deformation characteristics and genetic mechanism are significantly different.The Dazhangtuo parallel fault system on the western side is controlled by differential extension.A group of parallel tensional faults are developed on one side of the gentle bank zone.The strike of the faults is perpendicular to the inclination of the slope, forming a single slope structure on the background of the fault nose.The Changlu pinnate fault system on the eastern side and the Kaolin broom fault system are superimposed by extensional strike-slip action.Controlled, the strike of faults is parallel to the stratum tendency, forming a complex faulted slope structure along the direction.The evolution of the slope area has gone through three stages: initial rifting stage, rotary tilting stage and depression subsidence stage, which control the palaeogeomorphological characteristics, sedimentary system types and sand body distribution in the slope area.The difference of fault activity characteristics controls the difference of oil and gas migration and accumulation characteristics.Early-aging faults are easy to accumulate oil and gas in the middle and deep depths, and the inherited faults have the characteristics of multi-objective layers and three-dimensional oil-bearing on both sides.
Source tracing elements of K-feldspars of main rivers around Bohai Bay Basin
Lin Xu, Zhao Xitao, Wu Zhonghai, Li Chang'an, Liu Haijin, Li Zhaoning
2020, 39(6): 10-18. doi: 10.19509/j.cnki.dzkq.2020.0602
Abstract FullText HTML PDF icon855 icon3450
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The study on provenance identification of Bohai Bay Basin is great significance to its evolution, the uplift and erosion process of the peripheral orogenic belt, and the material diffusion of the continental shelf sea in eastern China.K-feldspar is one of the most important petrogenic minerals in the earth's crust, which is widely found in the river sediments, being representative in the study of source tracing.After long-distance river transportation, its element characteristics can still well record the information of its source area.Based on these facts, in this study, we rely on the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to analyze the geochemical index from the river detrital K-feldspar of the Bohai Bay Basin.The results show that the contents of Na2O, Al2O3, SiO2, K2O of K-feldspar grains from the Yellow River are significantly different from the Hutuohe River, Luanhe River, Liaohe River and Zhanghe River.In the two-dimensional scatter diagram of Al2O3, Na2O and K2O, the Al2O3 value of some Yellow River samples is lower than the others.The contents of Ba, Pb, Sr, Rb and Ca are the main parts of trace elements, especially the first four.In the two-dimensional scatter diagrams of Ba and Sr and Ba and Pb, the Yellow River is obviously different from the other four rivers, which makes it a characteristic river in the study of provenance tracing in the Bohai Bay Basin.
Tight gas resource potential and prospect of the Lower Carboniferous in Marsel block, Kazakhastan
Wang Yuan, Wang Shaoyong, Li Hao, Sun Yanda, He Haiquan, Wang Qinglong
2020, 39(6): 19-29. doi: 10.19509/j.cnki.dzkq.2020.0613
Abstract FullText HTML PDF icon779 icon3429
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The amount of discovered resource is not in consistence with resource evaluation results at all, which leads to little significant breakthrough in tight gas exploration of the Lower Carboniferous in Marsel block of Kazakhastan.Based on the analysis of high frequency sequences, well logging, oil testing and seismic data, the hydrocarbon source rock distribution, reservoir rock types and its physical properties, gas saturation of the Lower Carboniferous in Marsel block are reanalyzed.Both Monte Carlo Simulation Method and the finite method are applied, in order to reevaluate the tight gas resource potential and distribution in Marsel block.The results show that the distribution areas of effective source rocks of Serpukhovian and Visean can reach 1×104 km2.The TOC of source rocks is above 1.2% in the north and between 0.2%—1.2% in the south in Marsel block, all in the hydrocarbon generating peak stage.The reservoirs are reefal-shoal facies primarily interlayered with source rocks in a large area, with an average porosity of 6%, permeability below 10×10-3 μm2, and saturation between 45%—65%.With Monte Carlo Simulation Method, the recoverable resources are evaluated to be 155.1, 400.1 and 875.3 billion cubic meters under the probability of 90%, 50% and 10% respectively.Based on the finite method, the tight gas accumulation area is 6 000 km2, recoverable resource is 434.6 billion cubic meters, and the average abundance of recoverable resource is 0.07×108 m3/km2 belonging to the low-very low abundance tight gas resource.However, in "sweet spots" like northern ASSA, Terekhov, KNDK, it can be between 0.08×108 — 0.25×108 m3/km2.By referring to horizontal well SRV fracturing experiences and "sweet spot" optimization to enhance single well production, economic benefit of exploration and development can be realized in the Lower Carboniferous in Marsel block.
Discovery of 2.5 Ga quartz monzodiorite and its geological significance in Hezhang, western Guizhou
He Lianglun, Liu Yu, Yang Kunguang, Cai Jingchen, Wang Jun, Xu Yang
2020, 39(6): 30-42. doi: 10.19509/j.cnki.dzkq.2020.0615
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The western Guizhou is located at the southwest margin of the Yangtze Block.The record of 2.5 Ga magmatic events in the Yangtze Block is very little.The Hezhang quartz monzodiorite recently discovered in western Guizhou shows that the LA-ICP-MS U-Pb age of the rock is (2 542±9)Ma, which is the first late Neoarchean rock found in this area.The rock is mainly composed of plagioclase, alkaline feldspar, quartz, amphibole, biotite, etc.It has medium high content of SiO2 (59.2%-60.6%), Na2O (4.70%-4.85%), and Na2O/K2O (3.02%-3.19%)ratios, and low content of Al2O3 (17%-17.7%) and MgO(2.42%-2.61%).The total number of rare earth elements (REE) was 120×10-6-221×10-6, (La/Yb)N=(8.32-17.98), and the differentiation of light- and heavy-REEs was not obvious, which showed a right-leaning type.The rocks have negative anomaly of Eu, enrichment in large ion lithophile elements (LILEs)(Ba, Sr) and deficency in high field strong elements (HSFEs) (Nb, Ta, Ti).The samples have weak negative to positive εHf(t) value (-0.51-+6.93) and positive εNd(t) value (+0.22-+0.88).The rock has the characteristics of low-Al type and high HREE TTG series.The comprehensive study shows that this rock may be formed by partial melting of metasomatism between the oceanic subducted plate and the water-bearing mantle wedge in the low-pressure shallow environment under eclogite facies.The residual phases in the source area are mainly rutile and a small amount of amphibole.This first report of 2.5 Ga rocks confirms the existence of the Neoarchean basement in the southwest margin of Yangtze Block, which provides a basis for the study of detrital zircons of Neoarchean magmatic origin around the Yangtze Block and provides new information for the evolution of the Neoarchean crust of the Yangtze Block.
Grain size characteristics and origin of red earth in Yong'an, Fujian Province
Zhao Juxing, Li Chang'an, Huang Guangming, Jia Mingming, Lin Shuzhen, Zhang Huasong, Leng Yonghui
2020, 39(6): 43-51. doi: 10.19509/j.cnki.dzkq.2020.0621
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Based on analyzing the grain size of a red earth profile in Yong'an, which is the first discovery of red earth in western Fujian province, and comparison of grain size result in Yong'an, typical eolian deposit, modern fluvial sediment and red earth in other areas, the causes of the red earth in Yong'an are discussed in this study.The results show as follows: The component particles of the red earth in Yong'an are silt predominantly, clay secondly and sand least. All the samples name clayey silt; silt and clay increase gradually and sand decreases obviously from top to bottom of the profile.The average content of 10-50 μm is 29.71%, and far less than typical atmospheric dust sediments; Sand-silt-clay triangular plot, characteristics of grain size parameter, scattergram of grain size parameter, A-M, L-M chart and frequency curves indicate the red earth in Yong'an is neither aeolian origin nor typical alluvial origin.All of the discriminant analysis results are positive value, which display the water flow action.The red earth in Yong'an is the product of intense chemical weathering after alluvial origin; The red earth of other areas in Fujian Province, Taihe in Jiangxi Province and the first terrace of Dong River in Guangdong Province have the same origin.This study has further identified the distribution of red earth in Fujian province, and origin mechanism of red earth.
Reservoir characteristics and economic sweet classification scheme of Fuyu reservoir in Daqing Oilfield
Zhang Fan, Xiao Hanmin, Jiang Zhenxue, Shang Yunzhi, Zhu Lin, Li Xiaohui, Xiao Yang, Chen Zhixiang, Bao Lei, Yang Mingyang, Wang Yuxia
2020, 39(6): 52-63. doi: 10.19509/j.cnki.dzkq.2020.0605
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The resources of the Fuyu reservoir in the Daqing Oilfield are abundant. Due to the unclear characteristics of reservoir and lack of scientific sweet classification scheme, it is difficult to optimize the sweet in the study area. In order to clarify reservoir characteristics and sweet selection scheme in the study area, this paper uses core physical property, XRD, casting thin section, scanning electron microscope, rock mechanics tests, high pressure mercury intrusion tests and logging data to establish the physical properties and the brittleness model of the study area., which ultimately provides a basis for clarifying reservoir characteristics and sweet screening. The results reveal ① the study area belongs to low hole-ultra low permeability reservoir, brittleness index between 0.5-0.75 and the pore structure of the reservoir in the study area can be divided into four types. Type Ⅰ reservoirs have more large-pore throats and fewer small-pore throats, with a mean porosity is more than 11% and a permeability is more than 0.7×10-3 μm2, the mercury saturation is more than 75% and the connectivity is good. Porosity of type Ⅱ reservoirs mainly locates 9%-12% and a permeability is 0.3×10-3-0.7×10-3 μm2, the mercury saturation is more than 70% and the connectivity is good. Type Ⅲ reservoirs have fewer large-pore throats, but more small-pore throats. The porosity mainly locates 8%-11% and a permeability is 0.1×10-3-0.3×10-3 μm2. The mercury saturation is more than 60% and the connectivity is poorer than type Ⅰ and Ⅱ. Type Ⅳ reservoirs have few small-pore throats, with a mean porosity is less than 9% and a permeability is less than 0.1×10-3 μm2, and the mercury saturation is less than 60% which have poor connectivity and permeability. ② Combine physical properties, oily and brittleness of reservoir and use gray relation method to establish the economic sweet classification standard in the study area. The comprehensive score of type Ⅰ economic sweet is more than 0.55, and the comprehensive score of type Ⅱ economic sweet is in 0.4-0.55, and the class Ⅲ economic sweet in 0.25-0.4. The non-reservoir or dry layer comprehensive score is less than 0.25. The well was verified by the classification standard and found that the standardeffectively solves the error according to the log to judge whether the reservoir contains oil. ③ Sedimentation, diagenesis, and faults interaction control the development of economic sweet. Sedimentation controls reservoir physical properties and pore structure, and diagenesis increases reservoir heterogeneity, and the existence of faults greatly affects reservoir oil. The results establish a sweet classification model to provide a scientific basis for the selection of sweet in the study area.
Inclusion features and geological significance of the Tonglüshan skarn-type copper-iron (gold) deposit in Daye, Hubei
Zhao Yanyan, Tan Jun, Liu Xiaoyang, Zhang Ming, Chen Yang, He Di
2020, 39(6): 64-74. doi: 10.19509/j.cnki.dzkq.2020.0606
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The Tonglüshan copper-iron (gold) deposit is a typical skarn deposit in the middle and lower reaches of the Yangtze River in Hubei.In order to find the origin of skarn, the petrographic observation, microscopic temperature measurement and laser Raman analysis of the inclusions were carried out.The result shows that the uniform temperature of the fluid inclusions in the deposit ranges from 180 to 700℃, and the salinity ranges from 1.74% to 55.7% NaCleqv. From the skarn period to the quartz-sulfide period, the ore-forming fluids are from high temperature and high salinity to low temperature and low salinity.The result of laser Raman measurement shows that the melt inclusions contain garnet, calcite, hematite and water.Based on the petrography and petrofacies composition characteristics of inclusions, the early skarn of Tonglüshan deposit should be of magmatic origin.
Application of fuzzy analytic hierarchy process to mineral prospectivity mapping of polymetallic sulfide deposits in the Southwest Indian ridge between 46° to 52°E
Ma Yao, Zhao Jiangnan, Liao Shili
2020, 39(6): 75-82. doi: 10.19509/j.cnki.dzkq.2020.0622
Abstract FullText HTML PDF icon645 icon3546
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As a product of hydrothermal activity, seabed polymetallic sulfides have good prospects for mineralization and development potential, and it has become the focus of marine mineral exploration in various countries.Fuzzy analytic hierarchy process (FAHP), which combines fuzzy mathematics with expert knowledge, is a typical knowledge-driven quantitative prediction method for mineral resources.In this paper, the method is used to process the Polymetallic sulfide in the southwest Indian ridge.The weights of the nine evidence layers are calculated by combining expert experience.Finally, the gamma operator is used to synthesize the final prospective map.Through prediction-area (P-A) plot analysis, the optimal γ for FAHP was determined as 0.9.The threshold corresponding to different mineralization probability levels was determined by C-A fractal method, and the prediction performance of the method was evaluated.The results showed that in the prediction model based on FAHP, the area under the ROC curve was 0.887 and 90.5% of the known hydrothermal point and seismic point were predicted.Therefore, the method can effectively predict the favorable mineralization of the study area and can provide directions for future prospecting.
Distribution rule and main controlling factors of crude oil from different sources in Bonan Sag
Han Jinhu, Guo Xiaowen, Wang Xuejun, Wang Yongshi, He Sheng
2020, 39(6): 83-92. doi: 10.19509/j.cnki.dzkq.2020.0607
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In order to reveal the distribution rule and main controlling factors of crude oil from the Es3 and Es4 source rocks in Bonan Sag, group separation, gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) and other means were used to analyze the geochemical characteristics of crude oil and source rock, carry out the genetic classification of crude oil, determine the distribution rule of crude oil from different sources, and then explore the main factors of oil distribution.The results show that the contribution of source rocks in Es3 and Es4 intervals to crude oil is different.Based on the biomarker parameters, crude oil is classified into three groups (Ⅰ, Ⅱ and Ⅲ), of which group Ⅱ oil is subdivided into group Ⅱ1 and group Ⅱ2 oil. Oil-source correlation suggests that group Ⅰ oil originates from the Es3 source rock; group Ⅱ1 oil is derived from mudstone interlayer between the gypsum rock of the Es4 interval, group Ⅱ2 oil is from mudstone of the lower part of gypsum layer of the Es4 interval; group Ⅲ oil is from mixed source rocks in both of the Es3 and Es4 intervals, mainly from Es3 source rocks, and its distribution is related to faults.Combined with the analysis of geological features of Bonan Sag, it is considered that fault and gypsum salt rocks of the upper Es4 interval are the main factors affecting the distribution of crude oil from different sources.
Relationship between argillaceous content and distance to main faulted zone and fractures development in the platform carbonate rocks of Yijianfang Formation in Shunbei area, Tarim Basin
Zhou Bowen, Chen Honghan, Yun Lu, Tang Daqing
2020, 39(6): 93-102. doi: 10.19509/j.cnki.dzkq.2020.0609
Abstract FullText HTML PDF icon796 icon3431
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The exploration of carbonate "fault-karst" reservoirs in Ordovician strike-slip fault zone in Shunbei area of Tarim basin has become a hot spot recently.Multiple drilling wells in Shunbei area of Tarim Basin show that the fault zone and fracture development site generally have unusually high natural gamma logging values.Therefore, according to the parameters of abnormally high shale content, reflect the degree of fracture development, so as to indicate the development location of the reservoir containing mud fault solution.In this paper, the coherent properties of the T74 interface of Shunbei 1 strike-slip fault zone were extracted and interpreted by GeoEast software.Then, according to the natural gamma ray logging data of Yijianfang Formation in 5 Wells, the relationship between the abnormal high shale content of strike-slip fault zone and damage zone of platform carbonate rocks and the distance of main fracture zone and the degree of fracture development was discussed.The results show that the sedimentary environment of carbonate platform in Yijianfang Formation of Ordovician in Shunbei area is stable and the background argillaceous content is low.The argillaceous content at the core and fracture development site of the NE main fault is much higher than the background value of platform carbonate rocks, which decreases with the increase of distance from the PDZ and the decrease of fracture development, and finally approaches its background value.This indicates that the shale content can be calculated by natural gamma ray logging, which indirectly indicates the development degree of "fault-karst" reservoir in strike-slip fault zone.It provides a new thinking for reservoir evaluation of deep and super deep strike-slip fault zone.
Ore-forming fluid characteristics and metallogenic mechanism of Fenghuang Pb-Zn deposit, Hunan Province
Wang Hanyi, He Mouchun, Ding Zhenju
2020, 39(6): 103-111. doi: 10.19509/j.cnki.dzkq.2020.0610
Abstract FullText HTML PDF icon735 icon3434
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The southeastern margin of the Yangtze block is an important Pb-Zn metallogenic belt in China, however, the systematical research of Fenghuang ore field is still in progress. Taking the deposit as the research object, the characteristics, source and composition of ore-forming fluid were studied by means of fluid inclusion geology, isotope geochemistry and micro-laser Raman spectroscopy. The results show that LV type fluid inclusions are well developed in the deposit. The homogenization temperature, salinity and density are between 111.2-177℃, 4.1%-25.2%, and 0.98-1.09 g/cm3 respectively. Generally, it is a low-temperature, medium-high salinity and medium-density fluid. The gas phase composition of the inclusions in quartz and sphalerite is mainly CH4, and the liquid phase is mainly H2O. The results of H-O isotope analysis show that the ore-forming fluid is mainly formation-water. It is considered that the formation-water from the basin extracts the ore-forming materials in the deep strata, forming reducing ore-forming fluid together with CH4 and other reducing agents produced by organic matter retorting in the sediments, and moves upward along the contemporaneous fault structure and other channels. Finally, lead and zinc precipitate in the dolomite of the shallow Aoxi formation.
Residual strength of loess-gravel interface under snowmelt in Ili valley, Xinjiang
Huang Wei, Sun Chang, Xiang Wei, Ren Shicong, Ren Xiaohu, Liu Qinbing
2020, 39(6): 112-120. doi: 10.19509/j.cnki.dzkq.2020.0611
Abstract FullText HTML PDF icon738 icon3345
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In order to study the residual strength of the loess-gravel interface, this paper investigated the residual strength of the loess-gravel interface with different water content by improved ring shear tests, what's more, the scanning electron microscopy (SEM) was taken to study the microstructure of the loess-gravel interface.The results show that residual strength of the loess- gravel interface decreased with increasing of the water content, and strain softening occurred during tests.With the increase of normal stress and water content, the strain softening phenomenon became less obvious; The residual strength of the loess-gravel interface increased with the normal stress, and there was a good linear relationship, which met the Mohr-Coulomb strength criterion, The residual strength parameters of the loess-gravel interface decreased with water content increasing.There was a critical water content w=18% (near the plastic limit water content 19.1%), when the water content ranged from 10%-18%, the residual friction angle φr changed slightly (Δφr=5.4 °).Respectively, when the water content ranged from 18%-26%, the residual friction angle φr changed greatly (Δφr=9.0 °).In terms of microstructure, with the water content increasing, the soft "mud film" was formed on the loess-gravel interface and partially filled with uneven surface.Thus the shearing surface was smooth.Meanwhile, during the shearing process, the clay was dispersed and absorbed to the surface of the loess particles and partially filled the pores which lubricated the loess particles and reduced the residual strength.The research results of this paper could provide scientific reference for the formation mechanism and engineering protection of loess-gravel interface landslide in Ili Valley.
Evaluation of susceptibility to karst collapse on both sides of the Yangtze River in Baishazhou, Wuhan and preventive measures in the process of metro construction
Li Xi, Yin Kunlong, Chen Biaodian, Li Ye, Jiang Chao, Jia Yi
2020, 39(6): 121-130. doi: 10.19509/j.cnki.dzkq.2020.0612
Abstract FullText HTML PDF icon1019 icon3540
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In recent years, during urban engineering, there have been frequent karst collapses in Wuhan city, which seriously affects urban development and citizens security. In order to ascertain the susceptibility zone of ground collapse in karst area and put forward prevention measures, the Baishazhou karst belt along the Yangtze River is taken as the study area, and 7 indicators (karst development, soil thickness, soil structure, red-strata thickness, groundwater level fluctuations, karst water level fluctuation position and the density of collapse pit) are considered as evaluation factors. Based on this, a multi-factor discriminative model of karst collapse development is established employing analytic hierarchy process, and the study area is divided into different regions with high, medium and low susceptibility through GIS spatial analysis technology. Corresponding countermeasures and suggestion are proposed on the basis of geological structure for characteristics in different stages of the subway project in the region and their different sections of the susceptibility. The result shows high-susceptibility parts are mainly located in the covered karst area on both sides of the Yangtze River, and mostly contain sandy soil. High-susceptibility parts are the key of prevention and treatment, therefore, this area should be avoided during the planning phase, and the principle of prevention and control is mainly to prevent the leakage of the overlying sand particles. The principle of moderately susceptible zoning prevention is to prevent the formation and development of soil cavities in a single clay soil and to protect the integrity of the red layer. The thickness of the red layer for low susceptibility is greater than that of the engineering construction entering the bedrock, and the possibility of karst collapse is minimal. Our study can provide a reference for the constructions on the banks of the Yangtze River in Baishazhou, Wuhan.
Application of certainty factor and random forests model in landslide susceptibility evaluation in Mangshi City, Yunnan Province
Zheng Yingkai, Chen Jianguo, Wang Chengbin, Chen Tanwu
2020, 39(6): 131-144. doi: 10.19509/j.cnki.dzkq.2020.0616
Abstract FullText HTML PDF icon1222 icon3907
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Drawing up scientific zoning maps of landslide susceptibility can effectively reduce the loss caused by disasters.Taking Mangshi City, Yunnan Province as the research area, the researchers used certainty factor (CF) method to calculate the sensitive values of each factor, and used them as classified data of random forests (RF), selected appropriate training data and optimized model parameters, and finally established the prediction model of susceptibility in the research area.In this paper, the frequency ratio method is adopted to discretize the continuity factor, so as to calculate the landslide susceptibility of different sections of the factor through the deterministic coefficient.Meanwhile, CF prior model is used to select negative samples in the research area.The optimized RF parameters are obtained by calculating the out-of-pocket errors, and then the RF model is used to train and predict the research area model.ROC curve and 3D remote sensing image were drawn to evaluate the prediction model results quantitatively and qualitatively, and the results showed that the accuracy of the model was 91%, which was better than that of random sampling Finally, the importance of each factor in the study area was calculated and evaluated by using two calculation methods of average Gini impurity reduction and average accuracy reduction.Based on the above, the landslide vulnerability assessment is carried out in the study area to provide a basis for disaster risk assessment and management in this area.
Creep properties and stability of sliding zone soil in Gapa landslide
Zhang Xiaoqi, Hu Xinli, Liu Zhongxu, Liu Chang, Wu Shuangshuang
2020, 39(6): 145-153. doi: 10.19509/j.cnki.dzkq.2020.0604
Abstract FullText HTML PDF icon916 icon3376
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Deformation and failure of reservoir landslide are affected by creep properties and environmental factors ofits rock and soil.Therefore, it is of great significance to study the creep properties and stability of landslide.In order to study the creep characteristics and stability of landslide rock and soil, taking Gapa landslide near Jinping Hydropower Station as the research object, combining the analysis of slope surface displacement monitoring curve with indoor triaxial creep test, and the Burgers creep model was established and FLAC3D software was used to study the stability of landslide.Analysis of the slope surface displacement-time curve shows that the deformation characteristics of the slope are similar to the creep characteristics of the general landslide soil.The indoor triaxial creep test shows that the deformation of the sliding zone soil can be divided into three stages:instantaneous creep, decelerating creep and stable creep.And its instantaneous deformation and stable creep rate increase with the increase of confining pressure and stress level.Based on the calculation results of the Burgers creep model based on the creep characteristics of the sliding zone soil, the stability coefficients of the conventional strength reduction method and the strength reduction method considering creep are compared.In one calculation cycle, the strength reduction method considering creep is reduced by 0.04 compared with the conventional strength reduction method.Therefore, it is of practical significance to reveal the creep properties of landslide soil and study its stability.
Fuzzy comprehensive evaluation and its validation for shallow groundwater vulnerability in Jianghan Plain
Zhang Junshuai, Wang Bingguo, Liu Tianqi
2020, 39(6): 154-164. doi: 10.19509/j.cnki.dzkq.2020.0617
Abstract FullText HTML PDF icon581 icon4196
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Taking shallow groundwater of shayang-jiukou area in Jianghan plain as the research object to evaluate shallow groundwater vulnerability of Jianghan plain, is directed against the shortcomings of the traditional DRASTIC model, suchas strong relevance and weight subjectivity of evaluation indexes, discontinuity of the scoring values, and absence of measured data verification to the evaluation result. Considering the reality in the study area, a fuzzy comprehensive evaluation model is established on the basis of the improved DRASTIC model, and the accuracy and reliability of the model are verified by key pollution factors such as Cl-, NO3- and NH4+ in shallow groundwater. In this model, a new quantitative evaluation index system was built to make the evaluation indexes more objective and reasonable, which the impact of the vadose zone media, aquifer media and soil media were replaced by the thickness of cohesive soil in vadose zone, thickness of aquifer and soil saturated hydraulic conductivity respectively. The three-scale AHP method was adopted to determine the weight of each index, which reduced the subjectivity of the index weights from the traditional DRASTIC model. Based on the improved DRASTIC model, a fuzzy mathematics method was introduced, and the fixed scoring values of the indexes were replaced by the subordinating degree function to overcome the discontinuity of traditional DRASTIC model for using the quota scoring. The fuzzy comprehensive evaluation result showed that vulnerability evaluation of shallow groundwater in the study area is poor or comparatively poor on the whole, accounting for 76.53% of the study area. This research can provide method reference for shallow groundwater vulnerability evaluation in plain regions and scientific evidence for the prevention and control of shallow groundwater pollution in Jianghan Plain.
Source and enrichment mechanism of ammonium in shallow confined aquifer in the west of Dongting Plain
Huang Yanwen, Du Yao, Xu Yu, Tao Yanqiu, Deng Yamin, Ma Teng
2020, 39(6): 165-174. doi: 10.19509/j.cnki.dzkq.2020.0618
Abstract FullText HTML PDF icon914 icon3397
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Shallow confined aquifer is the main groundwater exploitation layer in the West of Dongting Plain, but it is faced with serious water shortage owing to worse water quality, among which ammonium anomaly is the most typical.However, its source and enrichment mechanism has been poorly understood at present.Taking the west of Dongting Plain as the study area, the hydrogeochemical analysis of groundwater samples along the direction of regional groundwater flow was carried out to find out the source of ammonium in groundwater and reveal the controlling mechanism of groundwater flow to the enrichment of ammonium.The results showed that the concentration of NH4-N was 0.05~16.75 mg/L, and had good positive correlations with DOC, HCO3-, As, Fe2+, Mn and P, while the high concentration of NH4-N corresponded to very low concentrations of Cl-, SO42-, NO3-, and very low Cl/Br ratio, it can be speculated that ammonium in shallow confined aquifer was produced by the mineralization of natural organic matter rather than anthropogenic input.Along the groundwater flow direction, the concentrations of NH4-N, As, Fe2+ and Mn increased significantly, indicating that with the more sluggsih groundwater flowed, the particles of water-bearing media were becoming finer and finer, and the organic matter in sediments was more and more enriched, thus the mineralization of nitrogen-bearing organic matter was gradually enhanced and the concentration of NH4-N increased gradually, forming a gradually reduced groundwater environment.As a result, the reductive components (arsenic, iron, manganese, etc) produced from related geochemical processes were also gradually enriched.The study further enriches the genetic theory of geogenic ammonium in groundwater and provides theoretical basis for the safety and security of local water supply.
Micro-pore multifractal characteristics of Benxi Formation sandstone reservoir in Gaoqiao area, Ordos Basin
Zhao Huitao, Guo Yinghai, Du Xiaowei, Hu Yunbing, Kang Rui, Shangguan Jingwen
2020, 39(6): 175-184. doi: 10.19509/j.cnki.dzkq.2020.0614
Abstract FullText HTML PDF icon968 icon3496
Abstract:
Eleven sandstone samples from Benxi Formation of Upper Paleozoic in Gaoqiao area of Ordos Basin were selected.The lithological characteristics and pore structure characteristics of the reservoir were analyzed based on rock slices and scanning electron microscopy.The distribution data of nuclear magnetic resonance T2 of sandstone samples were studied by using multifractal theory.The pore multifractal characteristics of sandstone reservoir are discussed, and the relationship between multifractal parameters and pore structure parameters, mineral composition and physical properties of sandstone is analyzed.The results show that the sandstones of Benxi Formation are mostly quartz sandstones and lithic quartz sandstones, and the skeleton grains are mainly quartz (63%-85%, with an average of 71.45%)and lithic debris(3%-17.5%, with an average of 10.91%), without feldspar.The cements are mainly kaolinite(3%-10%, with an average of 6.3%) and carbonate cements(0-9%, with an average of 5.65%).The pore size distribution of sandstone reservoir shows obvious multifractal characteristics.The multifractal parameters, Dmin-Dmax, Dmin/Dmax and Δα is between 1.16-1.83, 2.73-6.92 and 1.37-4.33 respectively.Research shows that both α-f(α) multifractal singular spectrum and q-D(q) generalized multifractal parameters can be used to quantitatively characterize the heterogeneity of pore distribution of sandstone reservoirs.The multifractal parameters have weak positive correlation and negative correlation with quartz content and rock debris content respectively, and have obvious negative correlation with cements content.The multifractal parameters are closely related to the permeability of reservoir.With the permeability increasing, the multifractal parameters show the trend of increasing first and then decreasing.Therefore, it is not that the smaller the heterogeneity is, the better the reservoir is.The development of a large number of intercrystalline pores can reduce the heterogeneity of the reservoir, but also greatly restricts the permeability of the reservoir.Relatively large pores are developed and have not undergone strong compaction, cementation and other diagenetic transformation.Reservoirs with weak heterogeneity are favorable areas for oil and gas exploration.
Flow calculation method and engineering application of non-standard triangle weir measurement method for rich-water faults
Mou Yongzhong, Zhou Chuanbo, Xiao Wenfang, Jiang Nan, Wu Tingyao, Du Chaofei, Liu Ganping, Liu Lei
2020, 39(6): 185-192. doi: 10.19509/j.cnki.dzkq.2020.0619
Abstract FullText HTML PDF icon946 icon3675
Abstract:
In the construction and operation of tunnels such as highways, railways, water conservancy and hydropower, and mines, it is inevitable to encounter geological disasters such as collapse and water inrush. The instability and destruction of surrounding rocks and seepage sudden change are the direct causes of water inrush. To find out the source of water inrush and the amount of water inrush in the area of F8 rich-water faults of Longnan tunnel, the non-standard triangular weir measuring method and the rectangular weir measuring method are used to monitor the flow of F8 surface upstream and downstream. In this paper, the basic concept of non-standard triangular weir method is put forward, and according to the flow formula of standard triangular weir measuring method and the principle of flow equivalence, the flow formula of non-standard triangular weir measuring method is derived. The rationality of the formula is proved by comparing the theory with the measured data. The results show that the derivation of the flow formula of the non-standard triangular weir measurement method provides convenience for the field flow measurement, overcomes the shortcomings of the application scope of the standard triangular weir measurement method formula, and provides a reliable basis for the analysis of the water inflow in the surrounding rock of the tunnel body in the fault fracture zone.
Research on mud shale fractures based on image logging: A case study of Jiaoshiba area
Gou Qiyang, Xu Shang, Hao Fang, Lu Yangbo, Shu Zhiguo, Wang Yuxuan
2020, 39(6): 193-200. doi: 10.19509/j.cnki.dzkq.2020.0620
Abstract FullText HTML PDF icon1079 icon3578
Abstract:
The fracture type, development and distribution characteristics of organic-rich mud shale are important factors that affect the accumulation and dissipation of shale gas.Based on core observation and high resolution micro-resistivity image logging (FMI), the fracture development characteristics of two key wells (JYA well and JYB well) in Jiaoshiba area were described and quantitatively interpreted.Besides, the influence of fracture on shale gas-bearing property is discussed in combination with gas-bearing data.The results show that there is little difference between JYA well and JYB well in main formation and underlying formation, and the bedding fracture is the main one, but the seal condition has obvious difference.The natural fracture of the direct seal of the JYA well is relatively low, mainly high-resistance fracture, followed by high-conductivity fracture and fault.The dip angle is 20.31°-75.83° (average 44.65°), 16.65°-61.17° (average 39.43°) and 36.41°, respectively.The line density of fracture in JYA well is 0.6 bar/ m, of which fault is 0.025 bar/m.The sealing condition of JYA well is well, and the production fracturing is high-yield.However, the natural fracture of the seal condition of the JYB well is relatively high, and mainly fault, followed by high-resistance fracture and high-conductivity fracture.The dip angle is 13.71°-72.23° (average 37°), 6.9°-78.49° (average 37.9°) and 13.53°-61° (average 32°), respectively. The linear density of fracture in JYB well can reach 0.98 bar/ m, of which fault is 0.654 bar/ m.The sealing condition of JYB well is low, and the production fracturing is low-yield.Fracture type and its degree determine the condition of shale gas preservation and the degree of shale gas enrichment in different blocks.

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