Study On The Exploration Of Mid Deep Geothermal Resources Based On CSAMT Data

As a new type of clean energy,geothermal resources have huge development potential and occupy an important position in my country’s economic development.The upper mantle uplift in Wuhan area has good deep geothermal conditions for the formation of geothermal resources.The study area is mainly carbonate karst heat storage,which has the conditions for the formation of large-scale heat storage.Therefore,the research has high practical significance.This thesis uses 6 CSAMT profiles composed of 304 measurement points collected in Jiangxia District,Wuhan City,and obtains a two-dimensional inversion model of underground resistivity in this area through geological data collection,data analysis,data processing,and fine inversion.Combining relevant geological data,discuss the formation mode of geothermal resources in the study area.On all cross-section models,there are low-high-resistance layered structures near the surface,and these two layers together constitute the thermal reservoir caprock of the geothermal system in the study area;under the anticline core in the study area,there is a large-scale The high-conductor in the form of a large mass is used as the heat storage structure of the geothermal system in the study area;the reservoir is connected to the surface through a high-conductivity fault zone developed in the northeast-south direction,and the fault zone serves as the heat flow channel structure of the geothermal system in the study area.The above inferred heat storage layer is formed in the core of the anticline structure in the study area,and its formation may be related to the protective effect of the thicker cap layer above it.The fractures as heat flow channels are formed on the two wings of the anticline structure in the study area.The above-mentioned connected fault-karst cave system basically coincides with the northeast-southwest trending Wutongkou-Tangxun Lake fault.Based on the resistivity model,we propose a geothermal resource formation model of "heat source-reservoir-channel-caprock" in Jiangxia area,Wuhan.The source of the heat source in the study area is: the deep mantle uplift heating the crust to form underground heat flow,and the supplementary heat source formed by atmospheric precipitation converges through the fault zone and is enriched in the thermal reservoir.The caprock is composed of a low-resistance layer of Quaternary sediments in the upper part,and high-resistance layers of dense Carboniferous-Triassic carbonate rocks and Silurian shale in the lower part.Insulate the heat preservation effect,so that the heat flow in the cave will not be lost.The core of the anticline structure with a thick cap layer is a favorable location for heat storage.The fracture zone plays the role of heat conduction and water conduction channel in the geothermal resource formation system.It is the combination of these conditions that makes the geothermal field formed in the study area.These conditions are indispensable.While completing the delineation of the thermal resource enrichment area in Jiangxia District of Wuhan City,this research also proposes the formation model of geothermal resources in this area,which provides a new idea for the application of controlled-source audio-frequency magnetotelluric method to the exploration of mid-deep karst thermal storage.