鄂尔多斯盆地上古生界山西组页岩气成藏条件及勘探潜力

为了研究鄂尔多斯盆地上古生界页岩气的勘探潜力，对鄂尔多斯盆地二叠系山西组富有机质泥页岩样品有机地球化学、物性特征及等温吸附等方面测试获得的参数进行了数理统计和测井响应特征分析。研究发现：有效泥页岩单层厚度变化较大，最厚可达15 m以上，盆地主体部位w(TOC)一般大于1.0%，有机质类型主要为Ⅱ₂型及Ⅲ型，镜质体反射率平均为1.66%，属于成熟-高成熟阶段，有利于有机质热解生气，具备页岩气成藏的基本地质条件。黏土矿物主要以伊利石（44.9%）和高岭石（33.6%）为主，泥页岩孔隙度平均为3.98%，渗透率平均为0.133×10^-3 μm²。泥页岩吸附含气量平均为1.94 m³/t。综合考虑泥页岩有效厚度、有机质丰度、有机质类型、热演化程度以及含气量等因素，预测鄂尔多斯盆地山西组页岩气有利区主要位于天环坳陷西北角、陕北斜坡带东北角及盆地中南部等区域。

Shale Gas Accumulation Condition and Exploration Potential of the Upper Paleozoic Shanxi Formation in Ordos Basin

In order to study the shale gas exploration potential of Upper Paleozoic in Ordos basin, organic-rich shale samples of Shanxi Formation are selected to test the organic geochemistry, physical properties and isothermal adsorption, etc. then the parameters are dealt with mathematical statistics methods and the corresponding logging characteristics are analyzed. Effective shale thickness changes greatly and it can reach more than 15 meters, the main part of TOC content is more than 1%, organic matter types are mainly type Ⅱ₂ and type III, vitrinite reflectance is 1.66% on the average and it belongs to mature-high mature stage which is good for the formation of pyrolysis gas. The Shanxi Formation has the essential conditions to form shale gas reservoir. Clay minerals are mainly composed of 44.9% illite and 33.6% kaolinite, shale porosity is 3.98% and permeability is 0.133×10^-3 μm² on the average, shale adsorption content is 1.94 m³/t. Considering the effective thickness of mud shale, organic matter content and type, degree of thermal evolution, gas content and other factors, the favorable shale gas areas  of Shanxi Formation are mainly located in the northwest corner of Tianhuan depression, the north-east corner of north Shaanxi slope and the central-southern part of Ordos basin.