摘要
运用压汞法和氮气吸附法分别对延长组页岩储层纳米级孔隙进行测定,通过等温吸附线和氩离子抛光扫描电镜照片描述,对孔隙结构特征分类表征并结合页岩样品岩石矿物组分、成熟度和有机碳含量测试讨论控制纳米级孔隙结构的主因。结果表明:延长组页岩储层孔隙主要为纳米级孔隙,并以中孔为主,占总孔体积的66%-84%,孔径主要分布在1-25 nm。其中长7段、长8段页岩的比表面积主要是由孔径小于5 nm的孔隙所提供的,长9段页岩的比表面积主要是由孔径小于10 nm的孔隙所提供的。延长组页岩吸附回线特征表明纳米级孔隙多以开放型为特征,主要包括有机质内部孔隙、黄铁矿莓状体粒间孔和黏土矿物粒间孔,以及部分长石溶蚀孔,此外页岩中还存在大量微裂缝。其中有机质内部纳米级孔隙和黄铁矿莓状体粒间孔是筒柱状孔,锥形孔、楔状孔及细颈瓶状或墨水瓶状孔的主要来源;长石溶蚀孔大多为半球形孔;黏土矿物粒间孔可贡献一端封闭或两端开口的筒状孔;微裂缝以平行壁狭缝状、弯曲波浪状、夹板形楔状为特征。有机碳含量是控制延长组页岩储层中纳米级孔隙体积及其比表面积的主要内因,页岩成熟度、黏土矿物含量和脆性矿物含量对纳米级孔隙控制作用不明显,但莓状体黄铁矿的增加有助于页岩中孔隙的增加。
The reservoir nanometer-scale porosity of Yanchang Shale was measured using mercury intrusion porosimetry and nitrogen adsorption method respectively. The pore volume,pore specific surface area,pore size and pore morphology were studied through the isotherms and SME images. Based on the mineralogy,maturity and TOC of Yanchang Shale,the main factors to control the nanopore structure of shale was discussed. The results show that the nanometerscale pores are dominated by mesopores which are 66%-84% of the total pore volume with pore sizes range from1 nm to 25 nm. In particular,the pore specific surface area of Chang 7 Shale and Chang 8 Shale are mainly providedby the pores that the aperture is less than 5 nm. The pore specific surface area of Chang 9 Shale are mainly provided by the pores that the aperture is less than 10 nm. The adsorption isotherm of Yanchang Shale indicate that most of nanopore are open,which mainly include organic nanopores,interparticle nanopores in pyrite framboids or in clay,and dissolution pores,moreover,a large number of microfractures developed in shale. In particular,the organic nanopores and interparticle nanopores in pyrite framboids are mainly in the shape of column,cone,wedge,flask and inkpot. The dissolution pores might provided the hemispherical pores. The interparticle nanopores in clay will be either the pores closed at one end or the open pores. The microfractures is characterized by slit Parallel to the wall,wavy and wedgelike plywood. The main internal factor to control the volume and the specific surface of nanopores of the shale gas reservoir in Yanchang Shale is TOC content,however,the control effect by the maturity,the content of clay and brittle mineral are not obvious for nanopores. The increase of pyrite framboids contribute to the increase of nanopores in shale.
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2014年第6期1118-1126,共9页
Journal of China Coal Society
基金
国家自然科学基金资助项目(41072098)
国家科技重大专项专题资助项目(2011ZX05018-001-002)
全国油气资源战略选区调查与评价国家专项联合资助项目(2009GYXQ-15)