黔西南区旧司组黑色页岩地球化学及储层特征分析

Analysis on reservoir characteristics and geochemistry of Jiusi Formation potential shale in southwestern Guizhou

秦文 唐显贵 秦琴 高为

1.贵州煤矿地质工程咨询与地质环境监测中心，贵州 贵阳 550081;2.贵州省煤层气页岩气工程技术研究中心，贵州 贵阳 550009

1.Guizhou Coalmine Geological Engineering Consultant and Geological Environmental Monitoring Center, Guiyang 550081, China;2.Research Center of Guizhou Coalbed Methane and Shale Gas Engineering and Technology, Guiyang 550009,China

黔西南区下石炭统旧司组泥页岩分布面积广，泥页岩层段发育厚，具有较好的页岩气产储条件。通过地球化学分析认为：旧司组黑色页岩有机质类型以Ⅱ型为主，有机碳质量分数分布在0.05%~5.76%，平均为1.25%，高值区主要分布在威宁、水城和晴隆地区，且旧司组下段的有机碳质量分数比上段高；有机质总体演化程度较高，处于过成熟生干气阶段。储层物性显示：旧司组黑色页岩的脆性矿物体积分数大于50%，黏土矿物体积分数在30%左右，易于压裂，开采条件好；孔隙类型主要为溶蚀孔、有机孔、晶内孔缝，孔隙体积以中孔体积为主；孔隙度为2.69%、渗透率为0.019 1×10－3 μm2、比表面积为7.091 m2/g，储集物性具有低孔隙—特低渗透的特征。岩石微裂缝和水介质对岩石抗压、抗拉强度有一定影响。综合分析地球化学和储层特征认为，有利区主要分布在水城—晴隆地区。

Lower Carboniferous shale of Jiusi Formation is wide distribution and thick in southwestern Guizhou. Shale gas has a good production and storage condition. Geochemistry analysis shows that the organic matter of Jiusi Formation potential shale is Type Ⅱ, TOC is 1.25% on average, high value areas are mainly distributed in Weining, Shuicheng and Qinglong Area, and Jiusi Formation TOC is higher in lower interval than that in upper interval. The evolution degree of organic matter is high on a whole and is at a dry gas stage in over mature. The physical property of reservoir shows that the clastic mineral content of Jiusi Formation potential shale is more than 50%, clay mineral content is about 30%, which is easy to fracture and has a good mining condition. Pore types are mainly dissolved pore, organic pore and intercrystalline pore and the pore volume is mesopore volume. Porosity is 2.69%, permeability is 0.019,1 md and the specific surface area is 7.091 m2/g. The reservoir has the characteristics of low porosity and extra- low permeability. Rock micro-fracture and water medium have certain influence on the rock compressive and tensile strength. Comprehensive study of organic geochemistry and reservoir characteristics shows that the favorable areas are mainly distributed in the Shuicheng - Qinglong Area.

10.6056/dkyqt201402010