滇黔北昭通示范区龙马溪组页岩气资源潜力评价

研究区位于滇黔北坳陷威信凹陷的中西部区域——川南低陡褶皱带南缘带,本文利用钻井、野外露头、区域地质等资料,对研究区龙马溪组页岩气基本地质特征进行了分析,并采用体积法对页岩气资源量进行了评价。研究成果表明,区内龙马溪组下段暗色页岩有机质含量及成熟度较高,有机质类型偏腐泥型;岩石脆性矿物含量高,物性一般,总含气量中等,总体与长宁、威远等邻区同层位产气页岩较为相似,并与北美主要产气页岩具有一定可比性。初步估算研究区龙马溪组页岩气资源量24871.8×10~8m~3,展现出良好的勘探前景,但受储层发育、保存条件等影响,页岩气资源分布严重不均,纵向上质量较好的页岩气资源主要集中在龙马溪组底部第1小层,平面上主要分布于研究区北部的川南低陡褶皱带内,该区内保存条件好的宽缓复向斜带和箱状背斜构造带是下步勘探的有利区。

Evaluation of shale gas resource potential of Longmaxi Formation in Zhaotong National Shale Gas Demonstration Area in the Northern Yunnan-Guizhou

The study area is located in the central and western part of Weixin Sag in the northern Yunnan-Guizhou to the southern margin of the southern Sichuan Low-steep fold belt. This paper analyzed the basic geological characteristics of the Longmaxi black shale using drilling, field outcrops, regional geology and other data. And the shale gas resource of Longmaxi black shale were evaluated by using volume method. The research results show that the studied Longmaxi black shale is relatively high in TOC, maturity and brittle mineral content, relatively saprolitic in organic matter type, and medium in physical properties and total gas content. The above characteristics of Longmaxi black shale has certain comparability with the major gas-producing shale in Weiyuan, Changning and North America. The preliminary estimation of shale gas resource of the Longmaxi Formation in the study area is 24871.8×10⁸ m³, which shows a good prospect for shale gas exploration. But affected by characteristics of reservoir development and preservation conditions, the shale gas resources are severely unevenly distributed. Shale gas resources with good quality are mainly distributed in the first layer, and the southern Sichuan low-steep fold belt in the northern part of the study area is the main area equipped with good quality resources. The wide anticline and box anticline structural belts with good preservation conditions are favorable areas for the next exploration.