Shuiwen dizhi gongcheng dizhi (Nov 2023)
Evaluation of geothermal resource potential in Shifogou based on geothermal geological conditions of the Lanzhou faulted basin
Abstract
Aiming at the problem of low degree of exploration and research of geothermal geological conditions in the Shifugou area, which seriously restricts the development and utilization of geothermal resources, on the basis of available data, the geothermal geological conditions and the characteristics of the thermal reservoir in the Lanzhou faulted basin are summarized. Combined with the exploration results of the controlled source audio frequency magnetotelluric (CSAMT) method, the potential of geothermal resources development in the Shifogou area in the southern part of the basin is inferred. The results show that (1) the geothermal geological conditions in the Lanzhou faulted basin are obviously different. Taking the buried faults of Shengouqiao (F5) and Leitai River (F8) as the boundary, respectively, the faulted basin can be divided into the western Xigu district, central Qilihe district and eastern Chengguan-Shifogou district. (2) The geothermal temperature increases from west to east, and increases vertically from the depth of 2000 to 2500 m, inferring that this is the basic depth of geothermal exploitation in the Lanzhou faulted basin. (3) In the southern section of the eastern part may exist layered-conductive geothermal resources and fault-zone geothermal resources, it is inferred that there may exist “combined type” of layered and banded geothermal water in the Shifogou district, which is located in the F2 fracture zone or the intersection of F2 fracture zone and F8 fault zone. It is suggested that the exploration and production well depth of geothermal water in the faulted-zone thermal reservoir should be considered as 800−1100 m, and that the exploration and production well depth of the “combined” layered thermal reservoir should be considered as 1500−2000 m. The wellhead geothermal water temperature in this area is expected to reach 50−60 °C, the single well yield can reach 500−1000 m3/d, and the quality of the geothermal water can reach the standard for medical bathing. The results can provide a basis for geothermal resources exploration in Lanzhou.
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