Resistivity response characteristics of coal cleats and optimization of logging interpretation using digital core technology

TianYu GU, Ze BAI, HaiBo WU

Prog Geophy ›› 2026, Vol. 41 ›› Issue (3) : 1122-1131.

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Prog Geophy ›› 2026, Vol. 41 ›› Issue (3) : 1122-1131. DOI: 10.6038/pg2026JJ0137

Resistivity response characteristics of coal cleats and optimization of logging interpretation using digital core technology

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Abstract

To investigate the relationship between the pore structure of coal cleats and the resistivity response, and to enhance the effectiveness and accuracy of evaluating coal cleat porosity using resistivity logging, this study analyzed the distribution characteristics of the coal cleat system based on X-CT scanning imaging technology: face cleats extend further, while butt cleats are distributed between face cleats and are approximately orthogonal to them. Digital coal rock models containing different cleat structures were generated by combining Fractal Brownian Motion(FBM) and successive Random Addition Algorithms (SRA). On this basis, the Finite Element Method(FEM) was used to simulate and study the influence of coal cleat type, dip angle, and porosity on resistivity. Finally, starting from the basic principle of the dual-laterolog iterative method, we proposed incorporating the power-law relationship between cleat porosity and the formation factor into the cleat porosity calculation process. This optimized the quantitative calculation method for evaluating coal cleat porosity using resistivity logging, forming a complete research path from microscopic structural characterization to macroscopic logging response, which breaks through the limitations of traditional methods that rely on idealized geometric models. The results show that: (1) The more developed the face cleats are, the more significantly the resistivity decreases; butt cleats also reduce coal resistivity to some extent, but their influence is less pronounced than that of face cleats. (2) When the cleat dip angle is constant, coal resistivity decreases following a power-law function as cleat porosity increases. When the cleat porosity is constant, the resistivity of coal containing low-angle cleats is significantly lower than that containing high-angle cleats. However, when the cleat porosity increases beyond a certain level, the influence of the cleat dip angle gradually weakens. (3) The cleat porosity calculated by the optimized dual-laterolog iterative method is numerically closer to the inversion results from NMR logging than the values obtained using the Aguilera cube model. Although certain deviations in the variation trend persist at different depth points, which may be attributed to factors such as localized resistivity anomalies caused by coal seam heterogeneity, the influence of fracture connectivity differences on conductive pathways, and limitations in X-CT scanning resolution, the overall evaluation effectiveness of coal cleat porosity based on conventional resistivity logging is improved. The calculation accuracy meets the requirements for coal seam log interpretation and can provide an important reference for coal reservoir resource assessment.

Key words

Digital core technology / Coal cleat porosity / Resistivity response / Logging interpretation

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TianYu GU , Ze BAI , HaiBo WU. Resistivity response characteristics of coal cleats and optimization of logging interpretation using digital core technology[J]. Progress in Geophysics. 2026, 41(3): 1122-1131 https://doi.org/10.6038/pg2026JJ0137

References

Aguilera R . Formation evaluation of coalbed methane formations. Journal of Canadian Petroleum Technology, 1994, 33 (9): 22- 28.
Bao H S , Han T C , Fu L Y . Calculation method of digital rock electrical conductivity based on two-dimensional images. Chinese Journal of Geophysics (in Chinese), 2021, 64 (5): 1733- 1744.
Chen G , Zhang J G , Li Q X , et al. Influential factors of the electromagnetic wave instrument while drilling in coal seam horizontal wells and resistivity simulation calculation. Coal Geology & Exploration (in Chinese), 2022, 50 (1): 45- 51.
Chen Y G. 2010. Study on fracture identification and evaluation base on well logging data[Master's thesis](in Chinese). Qingdao: University of Petroleum (East China).
Feng X J , Shen Y X , Zhou D , et al. Multi-scale distribution of coal fractures based on CT digital core deep learning. Coal Science and Technology (in Chinese), 2023, 51 (8): 97- 104.
Garboczi E J. 1998. Finite element and finite difference programs for computing the linear electric and elastic properties of digital images of random materials. Gaithersburg: National Institute of Standards and Technology, doi: 10.6028/NIST.IR.6269.
Kong Q F , Zhou C C , Zhang Y , et al. Numerical simulation methods of rock electrical properties based on digital cores: a review. Progress in Geophysics (in Chinese), 2015, 30 (2): 718- 724.
Liang X , Wang S , Zhou M S , et al. Coal seam porosity evaluation based on nuclear magnetic experiment and resistivity log. Coal Engineering (in Chinese), 2017, 49 (8): 130- 133.
Liu H L , Li G Z , Wang F , et al. Characteristics and genetic mechanisms of coal cleat systems in Qinshui Basin. Natural Gas Industry (in Chinese), 2008, 28 (3): 36- 39.
Liu Z D , Wang W , Yang J R , et al. Review and prospect of study on conductive properties of coal and CBM reservoirs. Progress in Geophysics (in Chinese), 2020, 35 (4): 1415- 1423.
Madadi M , Sahimi M . Lattice Boltzmann simulation of fluid flow in fracture networks with rough, self-affine surfaces. Physical Review E, 2003, 67 (2): 026309
Nie X , Li B K , Zhang J , et al. Numerical simulation of electrical properties of fractured carbonate reservoirs based on digital cores. Journal of Yangtze University (Natural Science Edition) (in Chinese), 2022, 19 (6): 20- 29.
Shang J H , Liu H H , Sang S X , et al. Coupling analysis on permeability and pore fracture development in high rank coal reservoirs of southern Qinshui Basin. Safety in Coal Mines (in Chinese), 2020, 51 (6): 184- 190.
Tan M J . Digital rock physics and its progress in log interpretation. Well Logging Technology (in Chinese), 2022, 46 (4): 371- 379.
Tang X Y , Chen X Y , Zheng L Q , et al. Review of conductive characteristics of gas-bearing coal. Science Technology and Engineering (in Chinese), 2023, 23 (25): 10617- 10624.
Wang F , Wu X , Duan C W , et al. CT scan-based quantitative characterization and fracability evaluation of fractures in shale reservoirs. Progress in Geophysics (in Chinese), 2023, 38 (5): 2147- 2159.
Wang S Y , Tan M J , Wang X C , et al. Microscopic response mechanism of electrical properties and saturation model establishment in fractured carbonate rocks. Journal of Petroleum Science and Engineering, 2022, 208: 109429
Yan Y G , Koplik J . Flow of power-law fluids in self-affine fracture channels. Physical Review E, 2008, 77 (3): 036315
Yang J Y , Du M L , Su X P , et al. The reserved characteristics of coal layer gas deposits and the evaluation of gas-bearing seam. Journal of Xi'an College of Geology (in Chinese), 1995, 17 (3): 77- 82.
Yu J , Li L , Qin R B , et al. Evaluation method and effect analysis of cleat porosity and permeability in high-rank coal bed based on resistivity logging. China Offshore Oil and Gas (in Chinese), 2021, 33 (5): 80- 86.
Zhao H , Shi X , Sima L Q . Study on porosity exponent, saturation and fracture porosity for fractured reservoirs. Progress in Geophysics (in Chinese), 2012, 27 (6): 2639- 2645.
Zhao J P , Sun J M , Liu X F , et al. Numerical simulation of the electrical properties of fractured rock based on digital rock technology. Journal of Geophysics and Engineering, 2013, 10 (5): 055009
宏帅 , 同城 , 力耘 . 基于二维图像的数字岩心电导率计算方法研究. 地球物理学报, 2021, 64 (5): 1733- 1744.
, 冀冠 , 泉新 , 等. 煤层水平井中随钻电磁波仪器影响因素分析及电阻率模拟计算. 煤田地质与勘探, 2022, 50 (1): 45- 51.
陈义国. 2010. 裂缝的测井识别与评价方法研究[硕士论文]. 青岛: 中国石油大学(华东).
雪健 , 永星 , , 等. 基于CT数字岩心深度学习的煤裂隙分布识别研究. 煤炭科学技术, 2023, 51 (8): 97- 104.
强夫 , 灿灿 , , 等. 基于数字岩心岩石电性数值模拟方法综述. 地球物理学进展, 2015, 30 (2): 718- 724.
, , 明顺 , 等. 基于核磁共振与电阻率测井的煤储层孔隙性评价. 煤炭工程, 2017, 49 (8): 130- 133.
洪林 , 贵中 , , 等. 沁水盆地煤层割理系统特征及其形成机理. 天然气工业, 2008, 28 (3): 36- 39.
之的 , , 珺茹 , 等. 煤及煤层气储层导电特性研究综述与展望. 地球物理学进展, 2020, 35 (4): 1415- 1423.
, 秉科 , , 等. 基于数字岩心的裂缝性碳酸盐岩储层电性数值模拟. 长江大学学报(自然科学版), 2022, 19 (6): 20- 29.
建华 , 会虎 , 树勋 , 等. 沁水盆地南部高阶煤储层渗透率与孔裂隙发育的耦合分析. 煤矿安全, 2020, 51 (6): 184- 190.
茂金 . 数字岩石物理学及测井解释应用概论. 测井技术, 2022, 46 (4): 371- 379.
小燕 , 昕怡 , 雷清 , 等. 含瓦斯煤岩导电特性研究综述. 科学技术与工程, 2023, 23 (25): 10617- 10624.
, , 朝伟 , 等. 基于三维CT重构的页岩裂缝定量表征及可压裂性评价. 地球物理学进展, 2023, 38 (5): 2147- 2159.
建业 , 美利 , 小鹏 , 等. 煤层气藏的储集特征及储层评价. 西安工程学院学报, 1995, 17 (3): 77- 82.
, , 瑞宝 , 等. 基于电阻率测井的高阶煤层割理孔渗评价方法及效果分析. 中国海上油气, 2021, 33 (5): 80- 86.
, , 司马 立强 . 裂缝性储层孔隙指数、饱和度及裂缝孔隙度计算研究. 地球物理学进展, 2012, 27 (6): 2639- 2645.

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