Numerical Model-Based Optimization of Production-reinjection Balanced Sustainable Exploitation Scheme for Geothermal Mine with Layered Karst Reservoir

Abstract

China is the worldwide leader in geothermal energy direct use. Some cities in the North China Plain, such as Xiong'an and Tianjin, have achieved a large scale of geothermal district heating using their excellent low-medium temperature Mesoproterozoic karst reservoirs and attracted global attention. To achieve the goal of carbon peak & carbon neutral, more clean & green geothermal energy will be needed with the rapid development of the utilization scale. Therefore, a sustainable exploitation scheme will be essential for a higher geothermal resource development degree. In recent years, the production-reinjection balanced mode has been the compulsory management requirement to take the heat without water consumption. On this background, sustainable exploitation still faces many challenges, like a degree of geothermal fluid temperature drop, heat breakthrough, and overlarge drawdown can all be constraint factors. A typical geothermal exploitation block with a certain degree of development in North China Plains is chosen for the sustainable scheme optimization study. Based on a numerical hydro-thermal model with reliable parameter estimation derived from production and tests, the mining area's temperature and pressure fields in the next 100 years with different (1) distances of production and reinjection wells, (2) single-well yields, and (3) reinjection temperatures are compared and discussed. The results can provide a scientific basis and accurate guidance for capacity expansion for the mining block in the near future.