摘要
煤岩系统内发育有nm^mm级的多种孔裂隙,系统表征其内部孔隙结构特征对查明煤岩物性和煤层气产出规律极为重要。基于对鄂尔多斯盆地东缘不同地区的系统采样,采用低温二氧化碳和液氮吸附、高压压汞和低场核磁共振系统表征了研究区煤岩的孔径结构。结果表明,二氧化碳吸附适用于0.6~1nm的微孔,液氮的主体适用范围在1~20nm左右,压汞可表征18nm以上的孔径。根据进汞饱和度、退汞效率和孔隙度将研究区煤岩划分为7个小类,并对应分析了进汞-退汞曲线特征。基于核磁共振表征了不同镜质体反射率和不同埋深的煤岩孔径大小的分布和连通性,随反射率升高和埋深加大,微小孔的比例呈现增加的趋势。相关成果对解释东缘范围内的煤储层物性特征,系统查明不同尺度煤岩孔径分布特征具有一定的支撑作用。
Multiple kinds of pores exist in the coal ranging from nm~ mm sizes,and a systematic characterization of the coal pore structure is of significant importance on clarifying coal physical parameters and coalbed methane production.Based on the system sampling in different areas of the east margin of Ordos basin,the pore system of coal at different scales was characterized by low temperature carbon dioxide and liquid nitrogen adsorption,high pressure mercury intrusion and low field nuclear magnetic resonance（NMR）.The results show that the CO2 adsorption can be used for characterization of pores between 0.6~1nm,and the liquid nitrogen adsorption suits for pores between 1~20nm,and the mercury intrusion can generally characterize pores lager than 18 nm.Based on mercury intrusion saturation,mercury withdraw efficiency and porosity values,the coals can be divided into 7types,with a discussion to their mercury intrusion and withdraw curves.The NMR method was used for characterization of pore sizes variations and connectivity of different vitrinite reflectance and different burial depth coals,which shows that the micropores increases as with the increase of vitrinite reflectance and also burial depth.The relative results can be used for characterization for coal physical parameters and a systematically characterization of coalpore size distributions of multiple scales.
出处
《中国矿业》
北大核心
2017年第4期146-152,共7页
China Mining Magazine
基金
中国矿业大学(北京)大学生创新训练项目资助(编号:C201602022)
国家自然科学基金项目资助(编号:41272175)
国土资源部公益性行业科研专项资助(编号:201311015)
关键词
煤层气
鄂尔多斯盆地东缘
孔隙结构
压汞
液氮吸附
核磁共振
coalbed methane
east margin of Ordos basin
pores structures
mercury intrusion
liquid nitrogen adsorption
nuclear magnetic resonance
