An analysis of physical characteristics and thermal structure of typical basins in eastern China

Abstract

China is rich in geothermal resources and mainly concentrated in basin areas, among which the large sedimentary basins in the east of china have great potential and demand for the development and utilization of geothermal resources.The basins in the east of china are characterized by large exploration depth, long development history, and high research degree.This paper focuses on the Songliao Basin, North China Basin and Zhangzhou Basin, which are representative in thermal storage characteristics in eastern China, as the study area. The deep boreholes above 4000m in three basins are selected for the study, and the physical columns (porosity, permeability and thermal properties) deep to the basement of the basin are constructed, and the water-heat transport patterns in different basins are elaborated.The main conclusions include the following , the difference of thermal conductivity and porosity of shallow geotechnical layers is a key factor leading to the redistribution of deep thermal energy in shallow layers of the earth, and the difference of physical properties is an intrinsic influencing factor of hydrothermal transport. The heat model of low permeability homogeneous thermal properties controlled in Songliao basin, high permeability and high thermal conductivity layer controlled in North China basin, and the water and heat by fracture network controlled in Zhangzhou basin are proposed.The Curie surface and Moho surface are indicative for the thermal structure of the basin, while the shallow Curie surface represents the strong thermal activity in the present time, which corresponding to the crustal source heat production, and the shallow Moho surface represents the strong mantle thermal activity in the historical period, corresponding to the mantle source heat production. The research provides theoretical guidance and data support for geothermal prospecting in eastern China.