甘肃西秦岭北麓与青海共和盆地干热岩赋存条件的对比分析

CONTRASTIVE ANALYSIS OF DRY-HOT ROCKS BETWEEN IN THE NORTHERN FOOT OF WESTERN QINLING MOUNTAINS OF GANSU PROVINCE AND IN GONGHE BASIN OF QINGHAI PROVINCE

发展新能源和建立清洁能源大基地是甘肃省“十三五”规划纲要中的“六大支柱”之一。笔者在广泛收集分析青海干热岩已有勘探资料及研究成果的基础上,结合甘肃西秦岭北麓地热异常(温泉、地热井)有限的勘探测试数据,分析研究了甘肃西秦岭北麓和青海共和盆地所处的区域地质构造背景,从干热岩形成条件和热储赋存特征两个方面进行了对比分析。研究认为甘肃西秦岭北麓与青海共和盆地具有相同的地质构造背景;西秦岭北麓规模较大的酸性岩体大部分直接裸露地表,属开启式地热田类型,岩浆岩侵入时代相对较早;岩体中放射性元素U、Th、K含量及放射性生热率略低于青海共和盆地;地层增温率6.O℃/100m左右,温度随深度基本上呈现线性增加,表现出以热传导为主的热源特征,推测在甘肃西秦岭北麓4000~5000m深度热储温度可达180℃-200℃以上,具备干热岩赋存条件。

The development of new energy and the establishment of clean energy bases are one of the "six pillars" in the 13th Five-Year Plan of Gansu Province. On the basis of extensive collection and analysis of the existing exploration data and research results of dry-hot rocks in Qinghai Province, combined with the limited exploration and testing data of geothermal anomalies (hot springs and geothermal wells) in the northern foot of Western Qinling Mountains in Gansu Province, the authors analyzed and studied the regional geological tectonic background, and made a comparative analysis from the formation conditions of dry -hot rocks and the characteristics of thermal storage. The study shows that there have been the same geological and structural background in the northern foot of the Western Qinling Mountains in Gansu Province and the Gonghe Basin in Qinghai Province, and most of the large-scale acidic rocks in the northern foot of the Western Qinling Mountains are directly exposed to the surface, belonging to the open geothermal field type, and the magmatic intrusion age is relatively early, and the content of radioactive elements U, Th, K and the radiogenic heat generation rate in the rocks are slightly lower than those in the Gonghe Basin in Qinghai Province. The stratum temperature increase rate is about 6.0℃/100 the temperature increases linearly with depth in the northern foot of the Western Qinling Mountains in Gansu Province, showing the characteristics of heat source dominated by heat conduction, and speculating that the temperature of 4 000-5 000 m deep thermal reservoir at the northern foot of Western Qinling Mountains in Gansu Province can reach 180℃-200℃, which is suitable for the occurrence of dry-hot rocks.