Main Controlling Factors and Formation Mode of Geothermal Anomaly in Eastern Chenghe Mining Area of Weibei Coalfield

Abstract

Geothermal anomaly has gradually become a prominent issue affecting the efficient mining of coal with the depth of coal mining increasing in eastern Chenghe mining area of Weibei coalfield. Here, we comprehensively investigated the distribution characteristics of the present geothermal field, analyzed the main controlling factors, and constructed forming mode of geothermal anomaly by the temperature measurement in surface borehole and underground water, combined with coal-rock thermal conductivity test. The results show that the geothermal gradient ranged from 25.7°C/km to 54.3°C/km. The areas with geothermal gradient greater than 30°C/km accounted for 88.31%, and there was the highest gradient value in the southeast F1 fault zone. The heat flow was between 66.81 mW/m2 to 128.49 mW/m2, which belonged to the obvious high heat flow area. Under the action of the main controlling factors such as fault, fold, coal-rock thermal conductivity, and groundwater activity in the region, the geothermal gradient and geothermal heat flow values showed an increasing trend from northwest to southeast. According to the distribution characteristics of heat flow and the action mechanism of main controlling factors, the geothermal anomaly in the study area was finally divided into two forming modes, i.e., fault-deep circulating hot water uplifting type and coal seam heat resistance-fold type. The research provides guidance for the geothermal hazard prevention of coal mine and the rational development and utilization of geothermal resources.