四川盆地五峰组—龙马溪组富有机质泥岩孔径分布及其与页岩含气性关系  

The Pore Size Distribution and Its Relationship with Shale Gas Capacity in Organic-rich Mudstone of Wufeng-Longmaxi Formation,Sichuan Basin

作　　者：张瑜[1] 闫建萍[1] 贾祥娟[1] 李艳芳[1] 邵德勇 于萍[1] 张同伟[1] 

机构地区：[1]兰州大学地质科学与矿产资源学院&甘肃省西部矿产资源重点实验室,甘肃兰州730000

出　　处：《天然气地球科学》2015年第9期1755-1762,共8页Natural Gas Geoscience

基　　金：国家重点基础研究发展规划"973"项目(编号:2012CB214701);博士学科点专项科研基金(新教师)(编号:20120211120032);国家自然科学基金(编号:41202095)联合资助

摘　　要：选取四川盆地长宁县双河镇上奥陶统五峰组—下志留统龙马溪组新鲜露头样品23个,渝东南黔浅1井岩心样品14个,运用氮气吸附法进行了孔径分布表征,并结合TOC、矿物组成含量和含气量在垂向上的变化及相关性分析,探讨了控制页岩孔隙发育的主要影响因素及其与页岩含气性的关系。结果表明：页岩孔隙以四周开放的具有平行板结构的狭缝孔为主,平均孔径为3.76～8.53nm,主体孔径以2～30nm的介孔为主。总体来看,BET比表面积和孔体积在五峰组—龙马溪组底部大,向上减小并趋于稳定,与TOC变化趋势一致,呈较好正相关性,表明有机质是控制龙马溪组页岩孔隙发育的主要因素。在TOC含量相近时,黏土矿物含量高的样品具有更大的比表面积,页岩中纳米孔隙的发育同时受黏土矿物的影响。四川盆地五峰组—龙马溪组底部TOC和脆性矿物含量高,有机孔发育,页岩含气性好,是页岩气储层压裂改造的优选层位。Pore size distribution for 23 fresh outcrop shale samples collected from Shuanghe Town,Changning County and 14 core samples collected from the well Qianqian 1in southeast Chongqing,Sichuan Basin were investigated by low pressure nitrogen adsorption.The main factors controlling pore development and gas accumulation in shales were discussed by integrating total organic carbon（TOC）,mineralogy and shale gas content.The results show that open slit-like and parallel plate structure are major pore types with an average pore diameter of 3.76-8.53 nm,and 2-30 nm mesopores are dominated.The BET surface area and total pore volume are high in the Wufeng Formation and lower part of the Longmaxi Formation,and the decrease in the upper part of the Longmaxi Formation,in consistent with the trends of TOC,suggesting that organic matter is the key controlling factor on the shale pore development.In addition,samples with higher content of clay minerals but similar TOCcontent have larger specific surface area,and the clay-mineral-hosted pores are present.The Wufeng Formation and lower part of the Longmaxi Formation in the Sichuan Basin are preferred layers of shale reservoir fracturing because of high TOC,high rock brittleness and high gas content.

关 键 词：四川盆地 页岩纳米孔隙 氮气吸附 含气性 比表面积 

分 类 号：TE122.2[石油与天然气工程—油气勘探]