摘要
为进一步揭示CO_(2)相变致裂煤的裂隙改造机理,开展了CO_(2)相变致裂煤体实验,基于CT扫描和三维裂隙重构,分析了CO_(2)相变致裂前后的煤样内部裂隙结构参数,查明了CO_(2)相变致裂煤的三维裂隙结构演化特征。结果表明,致裂后煤样的裂隙总数量减少,裂隙总体积和裂隙总表面积增加;CO_(2)相变致裂产生了裂隙扩张转化效应,在致裂压力的扩张作用下,小尺度裂隙转化为更大尺度的裂隙;长度小于1000μm的裂隙数量减少、裂隙体积和表面积明显减小,长度大于1000μm的裂隙体积和表面积明显增大,且裂隙之间扩张贯通而引起其数量减少;CO_(2)相变致裂大幅度改善了煤体三维裂隙的连通性,有利于气体的运移和产出。此研究为CO_(2)相变致裂效果提供新的分析评价方法,也可为其他非常规天然气储层及其改造的裂隙演化特征研究提供参考和借鉴。
This study conducted the CO_(2)-PTF coal experiment to further reveal the fracturing transformation mechanism of CO_(2)phase transition fracturing(CO_(2)-PTF)coal.According to the CT scanning and 3D fracture reconstruction,we analyzed the fracture structure parameters of coal before and after CO_(2)-PTF,and clarified the evolution characteristics of the three-dimensional fracture structure of coal induced by CO_(2)-PTF.The research results indicated that after CO_(2)-PTF,the total number of fractures in the coal sample decreased,while the total volume and surface area of fractures increased.The CO_(2)-PTF generated fracture expansion and transformation effects where the small-scale fractures were expanded and transformed into larger scale fractures under the CO_(2)-PTF pressure.The number,volume,and surface area of fractures of less than 1000μm in length were significantly reduced,while the volume and surface area of fractures of longer than 1000μm in length were significantly increased.The expansion and connection between fractures caused a decrease in their quantity.CO_(2)-PTF improves the connectivity of the three-dimensional fracture in coal and is conducive to gas migration and production.This study offers new insights into and evaluation method for the effect of CO_(2)-PTF,and could provide references for the research on fracture evolution characteristics in other unconventional natural gas reservoirs and their modifications.
作者
刘高峰
关文博
张震
李宝林
刘欢
司念
LIU Gaofeng;GUAN Wenbo;ZHANG Zhen;LI Baolin;LIU Huan;SI Nian(School of Resources&Environment,Henan Polytechnic University,Jiaozuo Henan 454003,China;Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization,Henan Polytechnic University,Jiaozuo Henan 454003,China;Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region,Henan Polytechnic University,Jiaozuo Henan 454003,China)
出处
《矿业科学学报》
CSCD
北大核心
2024年第3期342-350,共9页
Journal of Mining Science and Technology
基金
国家自然科学基金(42230814,42372204)
河南省高等学校重点科研项目(24B170005)
河南省科技攻关项目(242102320365)。
关键词
CO_(2)相变致裂
CT扫描
煤储层
三维裂隙演化
CO_(2) phase transition fracturing
CT scanning
coal reservoir
three dimensional fracture evolution
