摘要
【目的】为了有效强化煤层气抽采效果,将脉动压裂与超临界CO_(2)压裂相结合,提出了利用超临界CO_(2)脉动压裂煤(岩)的新思路。【方法】自主研发了超临界CO_(2)脉动压裂-渗流耦合真三轴试验系统,介绍了该试验系统的主要结构、特点和功能,然后开展了室内真三轴条件下超临界CO_(2)脉动压裂-渗流试验及超临界CO_(2)脉动压裂-声发射监测试验。该系统结合独立伺服系统与中央数字系统控制三向应力,采用双泵型恒速恒压泵脉动给压,具有高精度、全过程、真三轴、承载高温、高压及高应力的特点。【结果和结论】试验结果表明:超临界CO_(2)脉动压裂-渗流耦合真三轴试验系统可以实现良好的脉动压裂功能。超临界CO_(2)脉动压裂后,煤体渗透率较压裂前呈增大趋势,增大了2~9倍,且煤体渗透率皆呈现良好的指数变化规律。在声发射-超临界CO_(2)脉动压裂时期,煤体产生了新的裂隙通道,该通道由压裂孔中心直接贯穿至煤样表面,且可观测到超临界CO_(2)流体直接从煤中喷出,故超临界CO_(2)脉动压裂具有一定的扩展和连通裂隙的作用,能够有效提高煤层气的抽采效果。研究成果为强化深部低渗煤层增透技术提供了一定的试验支撑。
[Objective]To effectively enhance the extraction effects of coalbed methane(CBM),this study proposed a novel approach for fracturing coals(rocks)using pulsation of supercritical carbon dioxide(CO_(2))by combining pulsed fracturing with supercritical CO_(2) fracturing.[Methods]A true triaxial test system coupling supercritical CO_(2) pulsed fracturing with seepage was independently developed,and its primary structure,characteristics,and functions were elucidated.Then,the supercritical CO_(2) pulsed fracturing-seepage/acoustic emission monitoring tests under true triaxial conditions were conducted in the laboratory.The test system,controlling the triaxial stress by combining an independent servo system with a central digital system and achieving pulsed pressurization using a dual pump with constant speed and pressure,features high precision,true triaxiality,and resistance to high temperature,pressure,and stress and covers the whole process.[Results and Conclusions]The results indicate that the true triaxial test system that couples supercritical CO_(2) pulsed fracturing with seepage can achieve effective pulsed fracturing.Using supercritical CO_(2) pulsed fracturing,the permeability of coals can increase by two to nine times,manifesting a pronounced exponential growth.During the acoustic emission-supercritical CO_(2) pulsed fracturing,new fracture channels were formed in coals.These channels pen-etrated directly from the center of the fractured pores to the coal surface,with supercritical CO_(2) being observed ejecting directly from coals.Therefore,supercritical CO_(2) pulsed fracturing plays a certain role in propagating and connecting fractures,effectively improving CBM extraction.The findings of this study provide certain test support for reinforcing the permeability enhancement technology of deep,low-permeability coal seams and offer practical guidance for field CO_(2) fracturing engineering.
作者
刘佳佳
张云龙
聂子硕
高志扬
许文松
LIU Jiajia;ZHANG Yunlong;NIE Zishuo;GAO Zhiyang;XU Wensong(School of Safety Science and Engineering,Henan Polytechnic University,Jiaozuo 454003,China;State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,Anhui University of Science and Technology,Huainan 232001,China;Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization,Henan Polytechnic University,Jiaozuo 454003,China;State Key Laboratory of Gas Disaster Detecting,Preventing and Emergency Controlling,Chongqing 400037,China)
出处
《煤田地质与勘探》
EI
CAS
CSCD
北大核心
2024年第6期12-20,共9页
Coal Geology & Exploration
基金
国家自然科学基金面上项目(52074106)
河南省优秀青年科学基金项目(232300421061)
河南理工大学创新型科研团队项目(T2023-3)
深部煤矿采动响应与灾害防控国家重点实验室开放基金项目(SKLMRDPC22KF11)
瓦斯灾害监控与应急技术国家重点实验室开放基金项目(2021SKLKF01)。
关键词
超临界CO_(2)
脉动压裂
真三轴
渗流特性
声发射
supercritical CO_(2)
pulsed fracturing
true triaxiality
seepage characteristic
acoustic emission