四川盆地新区新层系页岩气的音频大地电磁探测——以川西南乐山地区须家河组为例  

Audio magnetotelluric detection of shale gas in the new horizon of the new area of Sichuan basin:a case study of the Xujiahe Formation in the Leshan area,southwest Sichuan

作　　者：王桥[1] 杨剑[1] 夏时斌 康建威[1] 李华[1] 张伟[1] 廖国忠[1] WANG Qiao;YANG Jian;XIA Shibin;KANG Jianwei;LI Hua;ZHANG Wei;LIAO Guozhong(China Geological Survey,Chengdu Center,Chengdu,Sichuan 610081,China)

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081

出　　处：《地质学报》2022年第2期699-711,共13页Acta Geologica Sinica

基　　金：中国地质调查局项目(编号DD20190033);国家自然科学基金项目(编号41804144)联合资助的成果。

摘　　要：四川盆地蕴含有巨量的天然气资源,经过十多年的地质理论发展,页岩气的勘探实现了较大突破,在盆地的南部和东南部探明了多个大型页岩气田,其主要的产气层位是上奥陶统五峰组—下志留统龙马溪组。四川盆地发育了六套富有机质页岩层系,其他的层位还没有取得大的突破,基础地质条件适合的盆缘地区可能是寻找经济型页岩气藏的有利区块。在分析前人的研究资料基础上,优选川西南乐山地区须家河组作为新区新层系的探测目标。根据研究区地质情况,构建理论电性参数模型,开展数值模拟试验,明确音频大地电磁方法的理论可行性。进而在重点研究区部署了一条音频大地电磁剖面,通过资料的处理和分析获得研究区的深部电性结构,结合地质资料提供了地质解释方案,配合钻井资料认为研究区一带具有稳定的地质结构、连续分布的富有机质页岩层以及好的页岩气显示。据此表明川西南乐山地区上三叠统须家河组作为页岩气勘探的新区新层系,可能具有良好的资源前景。Sichuan basin contains a huge amount of natural gas resources. After more than ten years’ development of geological theory, shale gas exploration has made a great breakthrough. In the south and southeast of the basin, several large shale gas fields have been discovered. The main gas producing horizon is the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation. However, there are six sets of organic-matter-rich shales in Sichuan basin, and other horizons have not made great breakthroughs. The basin margin area with suitable basic geological conditions may be a favorable block for looking for economic shale gas reservoirs. Based on the analysis of previous research data, the Xujiahe Formation in the Leshan area of southwest Sichuan basin is selected as the exploration target of the new horizon in the new area. According to the regional geological conditions, the theoretical electrical model is constructed, and the numerical simulation test is carried out to determine the theoretical feasibility of the audio magnetotelluric. In addition, an audio magnetotelluric profile is deployed in the key research area. The deep electrical structure of the study area is obtained by data processing and analysis. Combined with the geological data, the geological interpretation model is provided. Combined with drilling data, it is considered that the study area has stable geological structure, continuous distribution of organic-matter-rich shales and good shale gas content. It is suggested that the upper Triassic Xujiahe Formation in the Leshan area of southwest Sichuan may have a good resource prospect as a new shale gas exploration area.

关 键 词：四川盆地 页岩气 新区新层系 须家河组 音频大地电磁 

分 类 号：P618.13[天文地球—矿床学] P631.325[天文地球—地质学]