广东石坝地热田盖层特征及其对深层地热的影响

Characteristics of Cap Rock in Geothermal Field of Shiba,Guangdong and Its Effect on Deep Geothermal Resource

石坝盆地位于梅县—惠阳拗陷沉积区之内,主要出露古近系至第四系沉积地层,周围燕山期花岗岩分布广泛,区内花岗岩放射性生热率高。为查明区内干热岩资源赋存状况,通过基础地质调查、水文地质调查、地球物理勘查、及地球物理化学等多种技术方法,对区内的地层、构造、水文地质特征等进行了勘查,初步明确了盖层地质构造稳定,厚度大(3~4 km),富水性较贫乏,热导率远低于花岗岩体,这些特征均为干热型地热田的有利条件,也为今后干热型地热田的勘查提供了借鉴。

Shiba basin is located in the Meixian-Huiyang depression sedimentary area,mainly exposes Paleogene to Quaternary sedimentary strata.Yanshanian granite is widely distributed in the surrounding area and the radioactive heat generation rate of granites is high in the area.In order to find out the occurrence status of dry-hot rock resources in the area,the strata,geological structures and hydrogeological characteristics were investigated by means of basic geological survey,hydrogeological survey,geophysical exploration and geophysical chemistry.It was preliminarily clarified that the cap rock has stable geological structure,large thickness (3~4 km),poor water yield property and far lower thermal conductivity than granite body.All of them are favorable conditions for dry-hot-rock geothermal field,and also provide a reference for future exploration of dry-hot-rock geothermal field.