Heat source model for Enhanced Geothermal Systems (EGS) under different geological conditions in China

Abstract

A heat source is the basis for Enhanced Geothermal Systems (EGS) and is the most important factor for the site selection for EGS development. In this paper, we analyze regional variation patterns of mantle heat flow, study crustal thermal states, construct models of crustal steady-state temperature fields, and discuss the heat source mechanism of EGS in different zones, including the strongly tectonic activity zone of the Tibetan Plateau, North China sedimentary basin, and the highly radiogenic rock distribution zone of southeastern China. The results show that differences in the crustal thermal structure of different regions control their deep thermal conditions and EGS heat sources. The intense tectonic activity zone of the Tibetan Plateau, represented by the Gonghe Basin, shows an anomalously heated crustal thermal structure, and the low-velocity layer in its thickened crust provides the most important intracrustal heat source in the region. The local area in southeastern China is influenced by both highly radiogenic rocks and good sedimentary cover insulation, indicating a hot crust-cold mantle type of crustal thermal structure, thus reflecting the role of heat production from highly radiogenic rocks in controlling the shallow crustal temperature field in the area. The North China Plain has a typical cold crust-hot mantle type of crustal thermal structure, and the development of EGS in the area must consider the undulating bedrock pattern in the sedimentary basin and whether there is a deep fracture that connects the nearby mantle heat source. The results are of scientific significance for guiding future target site selection and EGS development in different regions.