3D Geological Model Construction And Reserve Evaluation Of Mine Geothermal Reservoir

The coal measure strata in Pingdingshan mining area have high temperature and large buried depth,and high temperature heat damage mines are common.There is karst geothermal water in some heat-harm mines in the mining area,which aggravates the high temperature heat damage of the mine.At the same time,the mine geothermal water also has good development and utilization value.In this thesis,the Cambrian limestone thermal reservoirs in some areas of Pingmei No.10 Mine,No.12 Mine and Shoushan No.1 Mine are taken as the research objects.The three-dimensional geological model of geothermal reservoirs in the study area is constructed by means of theoretical analysis,laboratory experiment and numerical simulation.The static resource evaluation of karst hot water and geothermal in geothermal reservoirs is carried out,and the dynamic resource of geothermal reservoirs is evaluated dynamically.The main research results are as follows:（1）A three-dimensional geological model of mine karst thermal reservoir is constructed.On the basis of regional hydrogeological background,by collecting and collating geological drilling data,the situation of’source’,’pass’,’cap’,’reservoir’and’flow’of geothermal reservoirs is analyzed.On this basis,the spatial structure of three-dimensional model of geothermal reservoirs is established,and the visualization of geothermal reservoirs and cap rocks is realized.The spatial parameter database of each node cell is obtained by meshing the spatial structure.（2）Evaluated the dynamic resources of karst geothermal reservoir.The thermal physical parameters of coal and rock in coal-bearing strata were tested,and the geothermal resources in the study area were evaluated based on the three-dimensional geological model of mine karst thermal reservoir.The results show that the geothermal water resources are 7.68×10⁹ m³,of which the geothermal resources are 1.13×10¹⁸ J,the available geothermal resources are 1.70×10¹⁷ J,equivalent to 5.83 Mt of tce.According to the calculation of the heat storage cell database,the dynamic relationship between the amount of geothermal water resources and the amount of geothermal resources and the head is obtained.（3）The influence of mining intensity and well spacing on geothermal water level is revealed.A three-dimensional unsteady flow numerical model of Cambrian thermal reservoir in the study area was established.Through the water pressure observation of Pingmei No.10 Mine geothermal wells at 450 m and 600 m in the machine bottom lane,the water level change is obtained.The observed water level and the calculated value of the model are identified and verified,so that the model conforms to the actual situation of the thermal reservoir.The final model results are in good agreement with the measured ones.The change of groundwater level drawdown under different mining intensity is simulated and analyzed.The results show that when the pumping volume increases by 1500 m³/d,the groundwater level decreases by an average of 5 m and an average annual decrease of 0.5 m in 10 years.The layout of the mining well is optimized,and the flow field after 10 years of mining under different well spacing is simulated.It is concluded that the layout of the mining well spacing of 100 m can indeed reduce the water level drop and the uneven phenomenon of drawdown.In actual production,the layout can be adjusted to increase the service life of the mining well or appropriately increase the mining intensity within a fixed mining period.