雷东记, 刘丽英, 贾子强,等.煤体水力压裂过程复电性频散响应特征实验研究[J].河南理工大学学报（自然科学版）,2024,43(4):48-55.

LEI D J, LIU L Y, JIA Z Q,et al.Experimental study on the characteristics of complex electrical dispersion response of hydraulic fracturing process in coal body[J].Journal of Henan Polytechnic University(Natural Science) ,2024,43(4):48-55.

煤体水力压裂过程复电性频散响应特征实验研究

雷东记1,2, 刘丽英1, 贾子强1, 刘宁1

1.河南省瓦斯地质与瓦斯治理重点实验室-省部共建国家重点实验室培育基地，河南 焦作  454000;2.中原经济区煤层（页岩）气河南省协同创新中心，河南 焦作  454000

摘要: 目的  为研究水力压裂过程煤体复电性频散响应特征， 方法  实测水力压裂煤体的复电阻实部R和虚部X，分析其变化以判断煤体内部裂隙发育进程，并用激发极化理论分析其频散特征。  结果  结果表明：（1）水力压裂过程中，每个压力点煤体实部频散曲线随频率变化均呈“三段式”型，虚部均呈“U”型；实部频散曲线随水压变化呈“先上移，后下移，压裂时大幅度下移”趋势。（2）虚部极值点可以敏感反应小范围弹性变形和剪切破坏造成的阻值变化，极值点频率能识别较大范围的剪切破坏，可作为预测煤体破裂的有效指标。（3）水力压裂过程中，由于煤体固气固交界面发生激发极化，煤体实部和虚部随频率出现“三段式”和 “U”型变化。（4）由于煤体压裂先出现弹性变形，随后出现剪切破坏，最终煤体含水导电通道完全贯通，实部频散曲线随水压变化呈“先增大，后减小，压裂时迅速下降”趋势。 结论  采用复电阻率法监测煤体水力压裂过程中的复电参数随水压变化规律并判断煤体裂隙发育进程，运用激发极化理论分析煤的水力压裂复电参数随水压和交流电频率变化的响应特征，为煤层频谱激电法在评价煤层裂隙和压裂效果奠定实验基础。

关键词:复电阻率法;水力压裂;响应特征;频散机理;激发极化

doi:10.16186/j.cnki.1673-9787.2023050057

基金项目:国家自然科学基金资助项目（51704101）；河南省高等学校重点科研项目（22A440003）；河南省高校基本科研业务费专项项目（NSFRF200307）

收稿日期:2023/05/30

修回日期:2023/08/30

出版日期:2024/07/15

Experimental study on the characteristics of complex electrical dispersion response of hydraulic fracturing process in coal body

LEI Dongji1,2, LIU Liying1, JIA Ziqiang1, LIU Ning1

1.State Key Laboratory Cultivation Base for Gas Geology and Gas Control，Jiaozuo  454000，Henan，China;2.Collaborative Innovation Center of Central Plains Economic Region for Coalbed /Shale Gas，Henan Province，Jiaozuo  454000，Henan，China

Abstract: Objectives In order to study the dispersion response characteristics of the complex electrical properties of the coal body during hydraulic fracturing，  Methods we measured the real part R and the imaginary part X of the complex electrical resistance of the hydraulically fractured coal body，analyzed their changes to determine the fracture development process inside the coal body，and analyzed their dispersion characteristics by excitation polarization theory.  Results The study shows that：（1）during the hydraulic fracturing process，the dispersion curves of the real part of the coal body at each pressure point are of “hree-stage” type with the change of frequency，and the imaginary part is of"U"type； the dispersion curves of the real part show an "upward shift first and then downward shift with the change of water pressure.The real part of the dispersion curve shows a trend of “first shifting upward，then shifting downward，and then shifting down significantly when fracturing”.（2）The extreme value of the imaginary part can be sensitive to the change of resistance value caused by small-scale elastic deformation and shear damage，and the frequency of the extreme value can identify the larger-scale shear damage，which can be used as an effective indicator to predict the coal body rupture.（3）In the process of hydraulic fracturing，due to the excitation polarization at the solid-gas-solid interface of the coal body，the solid and imaginary parts of the coal body show "three-stage" and "U" type changes with frequency.（4）As the coal body fracture first appears elastic deformation，then shear damage，and finally the water-containing conductive channel of the coal body is completely penetrated，the dispersion curve of the real part shows a trend of "first increasing，then decreasing，and rapidly decreasing when fracturing" with the change of water pressure.  Conclusions In this study，the complex resistivity method is used to monitor the change of complex electric parameters with water pressure during the hydraulic fracturing process of coal body and judge the fracture development process of coal body，and the excitation polarization theory is applied to analyze the response characteristics of complex electric parameters with water pressure and AC frequency in the hydraulic fracturing of coal body，so as to lay the experimental foundation for the evaluation of fracture and fracturing effect of coal seam by the spectral excitation method.

Key words:complex resistivity method;hydraulic fracturing;response characteristics;frequency dispersion mechanism;induced polarization