Characteristics of pre-Cenozoic bedrock geothermal reservoirs and their distribution in Leiqiong area, South China

ABSTRACT: The Leqiong area includes the Leizhou Peninsula in Guangdong Province and the northern part in Hainan Province. Through field geological exploration, data collection and arrangement of drilling data, laboratory experimental data, combined with the surrounding geological conditions of Leqiong Depression, on the basis of previous research results, the pre-Cenozoic geothermal reservoir distribution map of Leiqiong Depression was compiled, and the distribution of concealed granite geothermal reservoir was analyzed. 3 types of potential geothermal pre-Cenozoic geothermal reservoir formations in Leiqiong area are summarized: Mesozoic sandstones, Upper Paleozoic carbonates, and granites. The Mesozoic sandstones are mainly cretaceous, which are fluvial and lacustrine deposits. They are mainly formed in the fault basin of active continental margin, distributed in the south of Leizhou Peninsula and North Hainan area, and their thickness can reach more than 2000 m. The upper Paleozoic carbonates are mainly distributed in Weixinan sag, Northwest Beibuwan Basin. The granites are mainly distributed in the Zhanjiang depression, Yunlong uplift and encountered in wells drilled in topographic sags. The prediction of concealed granite can provide a basis for the future deep geothermal exploration and the optimization of favorable areas.