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黔北煤田上二叠统龙潭组煤系页岩气储层特征与勘探潜力评价

Shale gas reservoir characteristics and exploration potential analysis of Longtan Formation of the upper Permian Series in Qianbei Coalfield

  • 摘要: 贵州省上二叠统龙潭组是中国南方最重要的含煤地层,蕴含丰富的富有机质泥页岩,具有良好的页岩气成藏物质基础。以贵州省黔北煤田上二叠统龙潭煤系富有机质泥页岩为研究对象,通过对JC-1井岩心样品进行测试,对研究区的富有机质泥页岩的矿物组成、地球化学特征、孔隙结构和岩石力学参数等储层特征进行了研究并对页岩气勘探潜力进行了评价。结果表明:JC-1井泥页岩干酪根类型均为III型,有机质成熟度在2.0%~3.0%,处于过成熟早期生干气阶段,总有机碳含量(TOC)为0.56%~9.58%,平均3.97%。地球化学参数显示黔北煤田龙潭组泥页岩有机质类型与有机质成熟度匹配,有机碳含量较高,具有较好的生气能力。SEM场发射扫描电镜观测结果显示JC-1井泥页岩具有的微观孔隙主要包括粒内孔、粒间孔和微裂缝,具有丰富的微观孔隙,为页岩气提供了良好的储集空间。X射线衍射数据显示泥页岩脆性矿物含量为5.96%~87.27%,平均值为43.78%,脆性矿物含量较高,有利于进行压裂改造;泥页岩总厚达到48.03 m,占龙潭组总厚度的36.89%,具有2个有效页岩连续厚度大于15 m的层段。黔北煤田龙潭煤系富有机质泥页岩具备良好的生气条件、良好的储集条件与良好的可压裂性,泥页岩累计厚度与有效连续厚度较大,具有较大的页岩气勘探潜力。

     

    Abstract: The Longtan Formation of the upper Permian Series in Qianbei Coalfield rich in organic shale,the further research of the potential of shale gas is needed. This paper is based on the testing of mineral composition,geochemical characteristics,pore structure,rock mechanical characteristics of the well JC-1 in Qianbei Coalfield,researched the characteristic of shale gas reservoir and the potential of shale gas. The result shows that the kerogen types of mud shale in well JC-1 were all type III,The maturity of organic matter is basically 2.0%-3.0%,the value of TOC are between 0.56%-9.58%,average of 3.97%. Geochemical parameters show that the shale has a good gas generation capacity. The results of SEM scanning electron microscope showed that the micro-pores of JC-well shale mainly included intra - grain pores,intergranular pores,organic matter pores and microfractures. It provides a good reservoir for shale gas. X-ray diffraction data analysis showed that the content of brittle minerals in shale was 5.96%-87.27%,with an average value of 43.78%. The content of brittle minerals is high,so it is good for fracturing. The thickness of shales reached 48.03 m, which accounts for 36.89% of the total thickness of Longtan formation,and it has two There are two effective shale segments with continuous thickness greater than 15 m. Overall,the shale in Qianbei Coalfield has a good potential of shale gas.

     

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