不同地应力和注水流量影响下水力压裂裂隙扩展规律研究  

Study on Propagation Law of Hydraulic Fractures Affected by Different Geostress and Water Injection Flow Rates

作　　者：韩志勇 郑春山 HAN Zhiyong;ZHENG Chunshan(School of Safety Science and Engineering,Anhui University of Science and Technology,Huainan 232001,China)

机构地区：[1]安徽理工大学安全科学与工程学院,安徽淮南232001

出　　处：《煤炭技术》2025年第4期154-158,共5页Coal Technology

基　　金：国家自然科学基金项目(52274171);安徽省高校优青项目(2023AH 030042)。

摘　　要：水力压裂是有效提高煤层气抽采效率的方法之一,探究其裂隙扩展形态与规律尤为重要。采用PFC数值模拟程序,基于颗粒黏结模型和光滑节理模型匹配煤样结构特征,建立煤体水力压裂流固耦合模型,研究了各向地应力差和不同注水流量条件下,水力压裂过程裂隙扩展发育规律。结果表明:当各向地应力差值较大时(10 MPa),水力压裂裂隙倾向于沿着最大主应力方向延展。低地应力差比高应力差更易使裂隙向钻孔周围扩展,形成复杂的裂隙网,增大煤体有效改造体积。低注水流量较高注水流量更能均匀作用煤样,充分沟通天然裂缝,扩展煤体裂隙网络发育范围。但注水流量值较小时,裂隙扩展速度慢、长度值小。相关结果为现场提高水力压裂裂隙发育及煤体增渗效果提供理论参考。Hydraulic fracturing is one of the effective methods to improve the efficiency of coalbed gas extraction.It is particularly important to investigate the expansion form and mechanism of hydraulic fractures.Adopts the PFC numerical simulation.Based on the particle bonding model and smooth joint model,coal sample structure characteristics is matched.Hydraulic fracturing fluid-solid coupling model is established.The expansion and development rules of fractures during hydraulic fracturing under different ground stress differences and different water injection flow conditions are revealed.Results show that:When the differences in stress of different directions being large(10 MPa),hydraulic fractures tend to extend along the direction of the maximum principal stress.Small ground stress difference is easier to make cracks extending around the borehole,forming a complex crack network and increasing the effective permeability-increase volume in coal.Low water injection flow rate could uniformly act on the coal sample,fully communicate with natural fractures,and expand the development range of fracture network.However,when the water injection flow rate being low,the fracture propagation speed is slow and the length is small.Above results provide theoretical reference for improving the development of hydraulic fractures and increasing coal permeability in field application.

关 键 词：裂隙扩展 离散元分析 地应力差 注水流量 

分 类 号：TD712[矿业工程—矿井通风与安全]