基于氮吸附法的页岩有机孔隙结构表征  

Characterization of Shale Organic-Pore Structure Using the Nitrogen Adsorption Method

作　　者：张征 商少石 张志炳 李怀彬 黄华 ZHANG Zheng;SHANG Shaoshi;ZHANG Zhibing;LI Huaibin;HUANG Hua(Institute of Mineral Resources Research,China Metallurgical Geology Bureau,Beijing 101300;Huadian Central China Green Engergy CO.,LTD,Wuhan,Hubei 530000)

机构地区：[1]中国冶金地质总局矿产资源研究院,北京101300 [2]华电华中清洁能源有限公司,湖北武汉530000

出　　处：《地质与勘探》2021年第6期1408-1415,共8页Geology and Exploration

摘　　要：页岩的微观孔隙结构对页岩气的赋存至关重要,气体吸附法可以对页岩的微观孔隙结构进行表征。通过测量四川盆地东南丁山地区丁页1井不同深度样品的矿物含量、R_(o)值和TOC含量,结果表明丁页1井龙马溪组页岩样品的矿物含量比较稳定,有机质成熟度变化不大,均为过成熟。通过低温氮吸附法计算样品的比表面积和微、介孔容积和孔径分布,结果表明:(1)样品的平均孔径为2.8~4.9 nm,10 nm以下的孔隙提供了大部分的微、介孔容积。微、介孔容积为0.00136~0.0108 cm^(3)/g,平均0.004 cm^(3)/g,比表面积为2.54~13.69 m^(2)/g,平均6.68 m^(2)/g;(2)微、介孔容积、比表面积和TOC三者之间有很强的正相关性。通过计算TOC含量为0时的微、介孔容积和比表面积推算无机孔和有机孔之间的比例和其对比表面积的影响,发现有机孔提供了大部分的微、介孔容积,有机孔还是比表面积的主要贡献因素;(3)样品的吸附曲线符合IPUAC分类中的第Ⅳ型吸附曲线,样品的脱附曲线反映样品孔隙形态随TOC含量的增加,由楔形孔(不定型孔)变为连通的墨水瓶型孔(狭缝型孔)或墨水瓶型孔。The microscopic pore structure of shale is very important for the occurrence of shale gas,and the gas adsorption method can characterize such a feature.This work measured the mineral content,R_(o)value and TOC content of the samples from well Dingye 1 at different depths in the Dingshan area,southeast Sichua Basin.Results show that the mineral content of the Longmaxi Formation shale samples from well Dingye 1 is relatively stable,and the organic matter maturity does not change much,all being over-mature.The specific surface area,micro and mesopore volume and pore size distributions of the samples were calculated by the low-temperature nitrogen adsorption method.Results indicate that(1)the average pore diameter of the sample is 2.8~4.9 nm,and the pores below 10 nm dominate the micro and mesopores.The micro and mesopore volume are 0.00136~0.0108 cm^(3)/g,0.004 cm^(3)/g on average,and the specific surface area is 2.54~13.69 m^(2)/g,6.68 m^(2)/g on average.(2)There is a strong positive correlation between the specific surface area and TOC.Calculating the volume of micro and mesopores and specific surface area with the TOC content 0 permits to estimate the ratio between inorganic pores and organic pores and the influence of their contrast surface area.It is found that organic pores provide most part of the micro and mesopore volume,while organic pores remain the main contributor to the specific surface area.(3)The adsorption curve of the sample conforms to the type IV adsorption curve in the IPUAC classification.The desorption curve of the samples indicates that with the increase of TOC content,the pore morphology changes from wedge-shaped pores(unshaped pores)into connected ink bottle type pores(slit type pores)or ink bottle type pores.

关 键 词：页岩 有机孔 微观结构 气体吸附法 丁页1井 龙马溪组 四川盆地 

分 类 号：TE352[石油与天然气工程—油气田开发工程]