State Key Laboratory Cultivation Base for Gas Geology and Gas Control, Henan Polytechnic University
Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region

目的目的为研究水力压裂过程中煤体复电性频散响应特征,方法方法通过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为“三段式”,虚部均为“U”形;实部频散曲线随水压变化呈现“先上移,后下移,压裂时大幅度下移”的趋势。(2)虚部极值点可以敏感反映由于小范围的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现“先增大,后减小,压裂时迅速下降”的趋势。结论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,研究该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复电参数随水压和随交流电频率的响应特征,为煤层频谱激电法评价煤层裂隙和压裂效果奠定基础。

Objectives To investigate the dispersion response characteristics of the complex electrical proper⁃ties of coal during hydraulic fracturing, Methods the real part R and imaginary part X of the complex elec⁃trical resistance of the hydraulically fractured coal were measured. Their changes were analyzed to deter⁃mine the fracture development process within the coal body, and their dispersion characteristics were exam⁃ined using excitation polarization theory. Results The results showed that: (1) during the hydraulic fractur⁃ing process, the dispersion curves of the real part of the coal at each pressure point exhibited a “three-stage” pattern with frequency changes, while the imaginary part showed a “U-shaped” pattern. The real part of the dispersion curve shifted upward initially, then downward, and experienced a significant down⁃ward shift during fracturing. (2) The extreme value of the imaginary part sensitively reflected changes in re⁃sistance caused by small-scale elastic deformation and shear failure, while the frequency of the extreme value could identify larger-scale shear failure, serving as an effective indicator of coal rupture. (3) Due to excitation polarization at the solid-gas-solid interface during hydraulic fracturing, the real and imaginary parts of the coal exhibited “three-stage” and “U-shaped” variations with frequency, respectively. (4) As hydraulic fracturing progressed, elastic deformation occurred first, followed by shear failure, and eventu⁃ally, the water-conducting channels within the coal body became fully connected. This resulted in the dis⁃persion curve of the real part increasing initially, then decreasing, and dropping sharply during fracturing as water pressure changed. Conclusions The complex resistivity method was used to monitor the variations in complex electrical parameters with water pressure during the hydraulic fracturing process and to evaluate the fracture development process of the coal body. The excitation polarization theory was applied to analyze the re⁃sponse characteristics of these parameters with respect to water pressure and AC frequency. This study pro⁃vides an experimental foundation for evaluating coal seam fractures and fracturing effects using the spectral in⁃duced polarization method.

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)

雷东记,刘丽英,贾子强,等.水力压裂过程中煤体复电性频散响应特征试验研究[J].河南理工大学学报(自然科学版),2025,44(2):42⁃50.

LEI D J, LIU L Y, JIA Z Q, et al. Experimental study on the complex electrical dispersion response characteristics of coal during hydraulic fracturing[J]. Journal of Henan Polytechnic University (Natural Science), 2025, 44(2): 42-50.