Deep bedrock geothermal resources in the Maichen Sag, Beibuwan Basin and their potential for exploitation and utilization.

The Maichen Sag in the south-central part of the Beibuwan Basin is abundant in geothermal resources that have not been widely exploited and utilized due to inadequate research on it. This study evaluated the geothermal resources in the Maichen Sag based on the regional geological setting and geothermal conditions. Grid units for assessment and a geological model for areas with geothermal resources were established using spatial analysis techniques. The spatial distribution models of the physical and thermophysical properties of the geothermal reservoirs were also built using the Kriging interpolation method. Based on the terrestrial heat flow distribution in the target areas, the spatial distribution of the geo-temperature field through the inversion under the constraints of the temperature data from boreholes were predicted. Factors such as deep geo-temperature, thermophysical properties of rocks, and terrestrial heat flow values, were integrated into this quantitative evaluation of geothermal resources through the geological modeling-based volume method and the geothermal reservoir engineering-based numerical simulation method. The results show that the Maichen Sag has favorable heat source conditions with intersected, deep-rooted faults and widely developed Upper Paleozoic fissured granite geothermal reservoirs. The northern outer slope zone at a burial depth of 3-5 km on the tectonic plane of the basement in the sag is suggested to be a potential target area, where, as calculated using the volume method, is likely to be the home to the total geothermal resources of 80.4x109GJ (i.e., 2.75x109tonnes of coal equivalent (tce)) in the bedrock geothermal reservoirs at a burial depth of 3-6 km. The geotemperature of 172-201°C at a formation depth of 5 km in the sag also indicates that the deep geothermal resources are of high value for exploitation. [ABSTRACT FROM AUTHOR]