Geothermal Resource Evaluation Based on Geological Modeling in Fushan Sag, Beibuwan Basin

ABSTRACT: Fushan Sag is in the south of Beibuwan Basin, with rich geothermal resources and large development potential. Based on the regional geological background, geothermal geological conditions, this paper systematically analyzes the characteristics of thermal reservoir and evaluates the amount of geothermal resources based on geological modeling. The results show that The geothermal gradient in Fushan sag ranges from 2.48 to 4.68 °C/100m, with an average value of 3.35 °C/100m, the terrestrial heat flow values is 56.05-82.54 mW/m2 and the amount of deep geothermal resources within a range of 3-6 km is 1.4⁎1013J. 1. INTRODUCTION Deep geothermal resources, including hydrothermal resources and hot dry rock (HDR), geothermal resources are usually buried at a depth greater than 3 km, (Dai and Chen, 2008; Younger et al., 2012; Muffler and Cataldi, 1978; Pang et al., 2020; Tester et al., 2006; Wang et al., 2017, 2002; Wang et al., 2012; Williams et al., 2008; Zhang Y et al., 2020). Beibuwan Basin located in the northern part of South China Sea has been a key area for oil and gas exploration and development in recent years, and a large number of researches have been carried out on the basin structure, rocks, sedimentation, oil and gas reservoirs, etc. It is found in the process of oil and gas exploration that the overall geothermal temperature gradient in Beibuwan Basin is relatively high, and the geothermal temperature gradient of the Cenozoic stratum of the Sag area is generally in the range of 3.1-3.8°C/100m, and that the uplift area can reach 4-7°C/100m, indicating that the basin has the potential for geothermal resource development. Fushan Sag is in the south of Beibuwan Basin, with rich geothermal resources and large development potential, but the research degree is low and has not yet been exploited on a large scale (Zhu and Jiang, 1998; Li et al., 2012; Huang et al., 2012; Liu et al., 2008; Meng et al., 2009; Ma et al., 2012; Wu and Liu, 2021; Zheng et al., 2022; Gao et al., 2020; Dai et al., 2009; Li et al., 2007; Xu et al., 2021). Strengthening the research on the structure of the geothermal field, geothermal geologic conditions, amount of geothermal resources, and exploitation potential of the region is of great strategic significance to improve the energy structure of Hainan Island.