深部煤层单段/多段水力压裂增透效果对比  

Comparison analysis on permeability improved effect of single and multi section hydraulic fracturing in deep depth seam

作　　者：张春华[1] 张勇志[2] 李江涛 李腾达[2] 

机构地区：[1]辽宁工程技术大学矿业技术学院,辽宁葫芦岛125105 [2]辽宁工程技术大学安全科学与工程学院,辽宁葫芦岛125105 [3]煤科集团沈阳研究院有限公司,辽宁沈阳110016

出　　处：《煤炭科学技术》2017年第6期50-54,175,共6页Coal Science and Technology

基　　金：国家自然科学基金资助项目(51304112);辽宁省高等学校优秀人才支持计划资助项目(LJQ2015046);辽宁工程技术大学优秀青年教师提升计划资助项目(2015年度)

摘　　要：为对比深部煤层钻孔内单段和多段水力压裂增透效果,基于谢桥煤矿待揭8煤层赋存条件,分别建立了单段和多段水力压裂增透模型,运用RFPA^(2D)-Flow软件,模拟分析了水力压裂影响区内煤层水压场、应力场、裂隙场和渗透场特征和规律,并进行了效果验证。结果表明:单段压裂起裂时的煤体孔隙水压为7 MPa,多段压裂起裂时的煤体孔隙水压为16 MPa;煤层起裂后,单段压裂时钻孔中部煤体产生了明显的应力集中,而多段压裂时煤体应力分布虽有起伏但无明显应力集中;单段压裂时裂隙主要在钻孔中部位置向顶底板萌发延伸,有效压裂面积较小,多段压裂时各压裂段均可产生类似的裂隙场,有效压裂面积大;单段压裂时煤体渗透系数最大可达初值的249倍,多段水力压裂时最大可达初值的263倍。与钻孔单段水力压裂工艺相比,多段水力压裂可有效提高钻孔瓦斯抽采效果。In order to compare the permeability effects of a single section and multi section hydraulic fracturing in the deep seam boreholes,based on the deposition conditions of the proposed opened No.8 seam in Xieqiao Mine,a single section and multi section hydraulic fracturing and permeability improved models were individually established.A RFPA2D-Flow software was applied to simulate and analyze the features and law of the in-seam water pressure field,stress field,crack field and permeability field within the hydraulic fracturing influence zone and the effect verifications were conducted.The results showed that the pore pressure in the coal mass at the initial fracturing of the single section fracturing was 7 MPa and the pore pressure of the coal mass at the initial fracturing of the multi section fracturing was16 MPa.When the fracturing operation started in the seam,during the single section fracturing,there was an obvious stress concentration occurred in the borehole middle part of the seam.And when a multi section fracturing was in operation,the stress distribution of the coal mass would have ups and downs and would not have an obvious stress concentration. During the single section fracturing operation,the cracks would be expanded from the middle location of the borehole to the roof and floor,the effective fractured area would be small.In the multi section fracturing operation,each fracturing section would cause a similar crack field and the effective fracturing area would be large.During the single section fracturing operation,the permeability coefficient of the coal mass would be 249 times higher than the initial value.During the multi section hydraulic fracturing operation,the permeability coefficient of the coal mass would be 263 times higher than the initial value.In comparison with the single section hydraulic fracturing of the borehole,the multi section hydraulic fracturing could effectively improve the gas drainage effect of the borehole.

关 键 词：深部开采 多段水力压裂 孔隙水压 裂隙 煤层增透 瓦斯抽采 

分 类 号：TD712[矿业工程—矿井通风与安全]