贵州西部威水背斜地热赋存规律及靶区预测研究

威水背斜紧邻六盘水市区,具备形成中低温地热资源的有利地热地质条件,潜在地热资源丰富。但因区内地质构造条件复杂,人们对热储构造、类型、地热资源埋藏条件及空间分布特征等认识不够,以致该地区在地热资源开发利用方面尚未取得实质性突破。为研究威水背斜地热赋存规律并进行靶区预测,以前期的实际勘查工作成果为支撑,在对相关勘查资料综合整理和科学分析的基础上,通过对威水背斜地质背景、热源条件、热储构造特征、地热载体及其运移和补给等分析,明确了研究区地热资源类型属受埋深条件控制的板内中低温型,热源主要来自地层自然增温(即地温梯度),地热载体以地下水为主,热储构造类型主要为层状热储类型;结合已有地热工程施工情况,分析了该工程未能取得预期效果的关键原因,揭示了研究区热储层为泥盆系上统尧梭组、望城坡组和泥盆系中统独山组,根据热储层顶界深度等值线对威水背斜进行了靶区预测,推算可获得的理论保守水温为44.7~59.7℃,稳定地热水涌水量不小于500 m3/d,为下一步地热资源勘查与开发工作提供了依据。

Geothermal occurrence regularity and target area prediction in Weishui Anticlinein,western Guizhou Province

Weishui Anticline is close to the urban area of Liupanshui City, which has favorable geothermal geological conditions with the formation of low and middle temperature geothermal resources. So it is rich in potential geothermal resources. However, the geological structure conditions are complex. And we have not enough recognition on the corresponding structure, type, burial conditions and spatial distribution of geothermal resources, so the region in the development and utilization of geothermal resources has not yet made a substantive breakthrough. The study of Weishui Anticline geothermal occurrence regularity and target prediction, it is supported by the results of the preliminary exploration work. On the basis of the comprehensive analysis and arrangement of relevant exploration data and by analysis of Weishui Anticline geologic background, heating conditions, thermal reservoir structure, geothermal carrier and its migration and recharge, this paper clearly indicated that this area belongs to the low and middle temperature type controlled by buried depth condition. The heat source mainly comes from the natural temperature formation (i.e. geothermal gradient). The geothermal carrier is mainly based on the ground water, and the type of the thermal reservoir is mainly the type of the thermal reservoir. Combined with existing geothermal engineering construction, the key reasons that the project failed to achieve the expected effect were analysed. It reveals that the heat reservoir layers are the Upper Devonian Raoshuo Formation (D₃y) and Wangchengpo Formation (D₃w), and the Middle Devonian Dushan Formation(D₂d). According to the heat reservoir top boundary depth contour of Weishui Anticline, the authors carried out the target prediction. The theoretical conservative water temperature is 44.7-59.7 ℃, and the stable geothermal water inflow is not less than 500 m³/d, which provides a basis for the further exploration and development of geothermal resources.