碎软煤层顶板水力压裂多裂缝穿层扩展规律研究  

Study on the law of multi-fracture through-layer propagation of crushed soft coal seam roof by hydraulic fracturing

作　　者：张玉浩 杨永康[1] 王晨龙 ZHANG Yuhao;YANG Yongkang;WANG Chenlong(Key Laboratory of In-situ Modified Mining,Ministry of Education,Taiyuan University of Technology,Taiyuan 030024,China;School of Mechanical and Vehicle Engineering,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学原位改性采矿教育部重点实验室,山西太原030024 [2]太原理工大学机械与运载工程学院,山西太原030024

出　　处：《煤矿安全》2024年第12期63-71,共9页Safety in Coal Mines

基　　金：国家自然科学基金资助项目(51404167);山西省回国留学人员科研资助项目(HGKY2019038);山西省青年科学家自然科学基金资助项目(201901D211066)。

摘　　要：为了研究碎软煤层顶板水力压裂过程中多裂缝穿层扩展规律,应用扩展有限元方法,分析了间接压裂时不同地质参数、施工参数、压裂顺序等因素对多裂缝穿层扩展形态和缝间应力干扰的影响。结果表明:顶板岩层最小水平主应力越大,裂缝在煤层中扩展效果越好;煤岩层厚度越大,裂缝穿层扩展的可能性越小;压裂液注入速率越快,裂缝在煤层中长度增加,但缝间应力干扰范围不断变大;裂缝起裂角度越大,压裂裂缝转向距离增加,使裂缝主要在顶板内扩展;较大的裂缝间距能够保证压裂后多裂缝均匀扩展进入煤层;不同的起裂顺序下,多裂缝起裂顺序依次为左侧、右侧、中间时,压裂后在煤层中形成的水力裂缝长度和面积是起裂顺序依次为中间、左侧、右侧时的2倍;相比裂缝起裂顺序依次为左侧、中间、右侧时,同时起裂会增大应力干扰范围,裂缝起裂压力变高,在煤层中形成的面积更小。The effects of different geological parameters,construction parameters,fracturing sequence and other factors on the propagation patterns of multiple cracks and stress interference between cracks in indirect fracturing were analyzed by the extended finite element method(FEM)in order to study the law of multi-fracture through-layer propagation during hydraulic fracturing of crushed soft coal seam roof.The results show that the larger the minimum horizontal principal stress of the roof layer is,the better the spreading effect of the crack in the coal seam is.The greater the thickness of coal layer,the less the possibility of fracture propagation.As the injection rate increases,the length of crack in coal seam increases,but the interference range of stress between cracks increases continuously.The larger the fracture initiation angle,the larger the fracture turning distance,the fracture mainly spreads in the roof.The larger fracture spacing can ensure the uniform expansion of multiple fractures into the coal seam after fracturing.The length and area of hydraulic fractures formed in coal seam after fracturing are twice as long as those in middle,left and right fractures in different fracture initiation sequences.When the fracture initiation sequence is left side,middle side and right side,the stress interference range will be increased,the fracture initiation pressure will be higher,and the area formed in the coal seam will be smaller.

关 键 词：碎软煤层 应力干扰 多裂缝扩展 穿层扩展 水力压裂 

分 类 号：TD712[矿业工程—矿井通风与安全]