Heat Generation and Accumulation for Hot Dry Rock Resources in the Igneous Rock Distribution Areas of Southeastern China

Abstract

Hot dry rock (HDR) is an important geothermal resource and the primary direction of future geothermal development. Granite is particularly rich in radiogenic heat-generating elements (e.g., U, Th, and K) and is thus the main target for HDR development worldwide. Southeastern China contains the most abundant granite distribution in the country and accounts for more than 40% of the total granite area. This paper analyzes the rock radiogenic heat production, geothermal flux, crustal thermal structure, and reservoir temperature in the key exploration areas based on a systematic investigation of the distribution of granite resources and their heat generation characteristics. A heat generation and accumulation model of HDR resources is proposed for southeastern China. The results show that southeastern China can be characterized by a quadratic heat gathering model that includes a mantle source heat supply, intracrustal heat generation, fracture heat transfer, and cover heat preservation. Among these, the radiogenic heat production of granite is one of the main factors that affects shallow geothermal fields in this region. Fracture structure and cover conditions also exert a strong control on the gathering and dissipation of underground heat. The widely distributed and high-heat-producing tuffs and fused tuffs in the Zhangzhou area offer promising heat-generating and heat-gathering conditions for future exploration and development of hot dry rock resources in the area. The results provide important insight on the genesis and heat control factors of HDR resources in southeastern China and a theoretical reference for future HDR resource exploration and development practices in the region