莱阳凹陷水南组页岩气储层特征及可压性分析

Analysis on Characteristics and Compressibility of Shale Gas Reservoir in Shuinan Formation in Laiyang Depression

摘要:

莱阳凹陷水南组是山东省中生代暗色泥页岩发育最好的层位之一，为了获取水南组泥页岩可压性，对水南组页岩气储层开展岩性特征、有机地化特征、裂缝发育特征、脆性/黏土矿物特征、脆性指数等方面研究。结果表明：莱阳凹陷水南组泥页岩发育厚度为200～443m，泥地比大于70%；有机碳含量平均为1.38%，生烃潜量平均为4.42mg/g，干酪根以Ⅱ型为主，Ⅰ型次之，镜质体反射率为0.70%～1.30%，泥页岩中宏观裂缝和微裂缝发育，利于后期压裂诱导缝的产生；泥页岩脆性矿物平均含量为75.2%～94.1%，脆性矿物含量较高，采用改进岩石脆性指数评价方法计算水南组泥页岩样品脆性指数为28%～63%，水南组泥页岩脆性很强，说明水南组泥页岩具有较好的可压性，利于人工压裂改造形成网状体积裂缝，研究成果对水南组页岩气储层改造具有很好的借鉴意义。

Abstract:

Shuinan formation in Laiyang depression is one of the best strata of Mesozoic dark mud shale in Shandong province. In order to obtain the compressibility of mud shale of Shuinan formation, lithologic characteristics, organic geochemical characteristics, fracture development characteristics, brittleness mineralcharacteristics and brittleness index of shale gas reservoirs in Shuinan formation have been studied. It is indiate that the thickness of shale in Shuinan formation in Laiyang depression is 200～443m, and the ratio of mud to land is more than 70%. The average organic carbon content is 1.38%, the average hydrocarbon generation potential is 4.42mg/g. The kerogen is mainly type Ⅱ, followed by type Ⅰ, and the vitrinite reflectance is 0.70%～1.30%.The macroscopic fractures and microfractures developed well. It is good for the formation of induced fractures in the later period. The average content of brittle minerals is 75.2%～94.1%. The content of brittle minerals is high. According to the improved rock brittleness index evaluation method, the brittleness index of the mud shale sample of Shuinan formation is 28% ~ 63%. The mud shale of Shuinan formation is very brittle, which shows that the mud shale of Shuinan formation has good compressibility and is conducive to the formation of network volume fractures by artificial fracturing. The research results have a good reference significance for the reconstruction of shale gas reservoir of Shuinan formation.