Calculation method of reasonable well spacing in sandstone geothermal reservoir based on production-reinjection equilibrium simulation

(Objective) In order to achieve the goal of sustainable development and utilization of geothermal energy, it is necessary to clarify the production-reinjection well spacing under different reinjection quantities and reinjection temperatures. (Methods) Therefore, taking the thermal reservoir of Guantao Formation in northern Shandong as the research object, the conceptual model and mathematical model of layered thermal reservoir development are established. COMSOL Multiphysics multi-field coupling simulation software was used to establish a geothermal production-reinjection well spacing calculator. The accuracy of the model is verified by parameter fitting and simulation results. (Results) Then, based on the software APP compilation function, guided by the use of ordinary users, the relevant parameter input is simplified, and the APP for geothermal production-reinjection well spacing calculator is established. Different from the previous studies, which only gave the production-reinjection well spacing, in order to meet the actual production needs, the corresponding reasonable production-reinjection well spacing was calculated under different conditions. The calculation results show that when the exploitation quantities are 40m3/h, 60m3/h，80m3/h and 100m3/h，the reasonable production-reinjection well spacing without thermal breakthrough is 290m, 330m, 360m and 390m respectively.(Conclusion) It is concluded that: In the layered conductive sandstone thermal reservoir area of northern Shandong, after the conceptual model is simplified, the numerical simulation results are reliable, and the geothermal production-reinjection well spacing calculator can be established in this area. Hydrothermal numerical simulation is a powerful means to calculate the reasonable production-reinjection well spacing. It can determine the key parameters of geothermal development and utilization projects, such as exploitation quantity, recharge quantity, injection temperature and production-reinjection well spacing, which is conducive to the sustainable development and utilization of geothermal resources.