四川江油市马头山地区三叠系碳酸盐岩地热资源特征

马头山地区三叠系中统碳酸盐岩含水岩组主要为雷口坡组和嘉陵江组两个主要含水层位,岩性为浅灰—浅灰褐色细粉晶灰岩和深灰色块状云岩。上部热储盖层为侏罗系和三叠系上统致密、厚度巨大的碎屑岩,热储层为三叠系中统碳酸盐岩地层,热储下部隔水岩层为三叠系下统飞仙关组暗紫色含粉砂质钙质泥岩,三叠系碳酸盐岩地下水受香水逆断层影响,无法接受大气降水或地表水的补给,由地表大气降水形成的现代渗入成因水无法越过山前阻水断裂,与盆地地下水失去水力联系,研究表明该地区三叠系碳酸盐岩渗入成因水水压力系统与沉积成因水压力系统呈现出"互不相干的状态",地下水处于封闭、阻止的弱氧化—还原环境,不具备深循环地下水的补、径、排条件。本研究为合理开发该区域深层地热水资源、减少开发利用风险提供了理论依据,对相关区域地热资源开发具有重要理论价值和指导意义。

Characteristics of geothermal resources of Triassic carbonate rocks in the Matoushan area,Jiangyou, Sichuan

The main aquifer layers groups are Leikoupo Formation and Jialingjiang Formation in Middle Triassic carbonate rocks at Matoushan area, with the lithology of light grey and light brown fine-crystal limestone and dark grey massive dolomite. The upper geothermal reservoir cap rocks consist of the compacted thick clasoliteof Jurassic and Upper Triassic. The thermal reservoir rocks are formed by the Middle Triassic carbonate rocks layers and the aquicluderocks of lower thermal reservoirare developed by the dark purple silty and calcareous mud stone of Feixianguan Formation of Lower Triassic. The underground water from Triassic Carbonate Rocks cannot accept the supply of meteoric water or surface water due to the impact of broken inverse layer, therefore the modern infiltration forming water formed by surface water or meteoric water cannot pass over the piedmont blocking water faulted structure, resulting to lose the connection with basin groundwater.Research has shown that the pressure water system of infiltration forming water from Triassic carbonate rocks has no connection with pressure water system of sedimentary forming water. Therefore the underground water system has no characteristics of recharge-runoff-discharge when it is in a condition of enclosed weak oxidation-reducing. This study provides a theory basis for reasonable development and risk control on development and utilization of deep geothermal water resources at Matoushan area as well as the important theoretic value and actualguidingsignificance of geothermalresourcesexploitation at the related areas.