黔东南牛蹄塘组富有机质页岩比表面积特征

Characteristics of specific surface area of organic-rich shale in Niutitang Formation in southeastern Guizhou

为了探寻黔东南地区牛蹄塘组页岩气吸附空间的展布规律,寻找页岩气储集的有利层段,对瓮安、余庆、镇远、三穗和天柱等地牛蹄塘组地表露头观察并系统采样,优选部分样品开展有机碳含量、热演化程度、石英含量、黏土成分和比表面积分析测试并进行相关性分析。测试结果显示:研究区有机碳平均含量为4.46%,平均热演化程度为3.16%,石英平均含量为56.64%,平均比表面积为11.88 m^(2)/g,具有高有机碳含量和低比表面积特征。相关性分析显示研究区比表面积与有机碳含量、热演化程度以及石英含量的相关性不明显,蒙脱石含量低可能是导致研究区比表面积低的主要因素。采样点平均比表面积分布特征表明,研究区西部瓮安—余庆具有较高的比表面积,是页岩气吸附空间较有利地区。该研究成果对黔东南地区页岩气勘探寻找有利储集空间有较好的借鉴价值。

In order to explore the distribution law of shale gas adsorption space in the Niutitang Formation in southeastern Guizhou and find favorable intervals for shale gas storage,the Niutitang Formation in Weng’an,Yuqing,Zhenyuan,Sansui,Tianzhu and other places,the surface outcrops were observed and systematically sampled,and some selected samples were tested for organic carbon content,thermal evolution degree,quartz content,clay composition and specific surface area,and correlation analysis was carried out.The test results show that the average content of organic carbon in the study area is 4.46%,the average thermal evolution degree is 3.16%,the average content of quartz is 56.64%,and the average specific surface area is 11.88 m^(2)/g,which has the characteristics of high organic carbon content and low specific surface area.The correlation analysis shows that the specific surface area of the study area has no obvious correlation with the organic carbon content,thermal evolution degree and quartz content,and the low content of montmorillonite may be the main factor leading to the low specific surface area of the study area.The distribution characteristics of the average specific surface area of the sampling points show that Weng’an-Yuqing in the western part of the study area has a relatively high specific surface area and is a favorable area for shale gas adsorption space.The research results have good reference value for shale gas exploration in southeastern Guizhou to find favorable reservoir space.