多尺度联合表征的低阶煤不同宏观煤岩成分孔隙特征差异  

Differences in pore characteristics of different macroscopic coal rock components in low rank coal based on multi-scale joint characterization

作　　者：祝浩冉 陈跃[1] 王怀厂[2] 马东民[1] 李国富 季长江 王馨 石金波 ZHU Haoran;CHEN Yue;WANG Huaichang;MA Dongmin;LI Guofu;JI Changjiang;WANG Xin;SHI Jinbo(College of Geology and Environment,Xi’an University of Science and Technology,Xi’an 710054,China;Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China;State Key Laboratory of Co-extraction Coal and Coalbed Methane Technology,Jincheng 048000,China)

机构地区：[1]西安科技大学地质与环境学院,陕西西安710054 [2]中国石油长庆油田分公司勘探开发研究院,陕西西安710018 [3]国家能源煤与煤层气共采技术国家重点实验室,山西晋城048000

出　　处：《西安科技大学学报》2025年第2期404-418,共15页Journal of Xi’an University of Science and Technology

基　　金：国家自然科学基金项目(41902175);低渗透油气田勘探开发国家工程实验室2024年度开放课题项目(KFKT2024-02);山西省揭榜招标项目(20201101002)。

摘　　要：为探究低阶煤不同宏观煤岩成分孔隙特征差异,以黄陇侏罗纪煤田园子沟井田延安组低阶煤为研究对象,运用高压压汞试验、液氮吸附、二氧化碳吸附、核磁共振及扫描电镜等方法对比分析低煤阶镜煤和暗煤的孔隙特征差异。结果表明:镜煤微米级孔隙不发育,但是镜煤性脆,在内外应力作用下易发生破裂产生微裂隙,而暗煤微米级孔隙则相对发育,主要为原生纤维结构和胞腔孔,偶见原生屑间孔和气孔;暗煤的有效孔隙度明显大于镜煤,煤中部分孔隙是闭孔和不连通孔隙,暗煤孔隙的连通性优于镜煤;镜煤的孔隙体积和比表面积均大于暗煤,镜煤的微孔和裂隙发育,而暗煤的介孔较为发育;在相对压力小于0.5阶段,镜煤介孔的分形维数小于暗煤,镜煤孔隙表面比暗煤平滑;基于压汞法计算大孔的分形维数发现,在孔径50~1000 nm区间,镜煤大孔的分形维数大于暗煤,镜煤大孔结构更加复杂,在孔径>1000 nm区间,镜煤的平均分形维数小于暗煤,镜煤裂隙发育,渗流能力较强。研究成果对进一步认识煤的孔隙结构特征以及对煤层气的吸附解吸机理研究具有重要意义。To explore the differences in pore characteristics of different macroscopic coal rock components in low rank coal,the Yan’an Formation low rank coal in the Yuanzigou coalfield of Huanglong Jurassic coal field was taken as the research object.Multiple technical means such as high-pressure mercury intrusion experiment,liquid nitrogen adsorption,carbon dioxide adsorption,nuclear magnetic resonance,and scanning electron microscopy were used to compare and analyze the differences in pore characteristics between low rank vitrain and durain.The results show that the micron-level pores of vitrain are not well-developed,but the vitrain is brittle and prone to rupture under internal and external stresses to produce microfractures.The micron-level pores of durain are relatively developed,with mainly primary fibre structure and cell-cavity pores,and occasionally primary inter-fragmentation pores and stomatal pores.The effective porosity of durain is significantly larger than that of vitrain,and some of the pores in the coal are closed and disconnected pores.The connectivity of the pores in the durain is better than that of the vitrain.The pore volume and specific surface area of vitrain are larger than that of durain,and the micropores and fractures of vitrain are developed,while mesoporous of durain are relatively developed;In the P/P 0<0.5 stage,the fractal dimension of vitrain mesoporous is greater than that of durain,indicating that the pore surface of vitrain is rougher than that of durain;In the range of pore size 50~1000 nm,the fractal dimension of vitrain macropore is greater than that of durain,indicating a weaker diffusion ability of vitrain macropores.In the range of pore size>1000 nm,the average fractal dimension of vitrain is smaller than that of durain,indicating the development of vitrain fractures and strong permeability.The research results are of great significance for further understanding the pore structure characteristics of coal and research on the adsorption and desorption mechanism of coalbed methan

关 键 词：宏观煤岩成分 低阶煤 孔隙特征 联合表征 分形维数 

分 类 号：TE822[石油与天然气工程—油气储运工程]