地质科技通报2025，Vol.44Issue(2)：224-237,14.DOI:10.19509/j.cnki.dzkq.tb20230533
基于三轴压缩模拟试验的页岩低阻成因机制
Genetic mechanism of low resistance in shale analyzed via triaxial compression tests
摘要
Abstract
[Objective]The gas-rich Wufeng-Longmaxi shale of the southern Sichuan Basin exhibits low-resistance anomalies in multiple areas.Statistical analysis reveals that the low-resistivity zone(<10 Ω·m)in the Wufeng-Longmaxi shale is spatially associated with tectonic faults.This study aims to reveal the coupling mechanism between shale resistivity and tectonic faults.[Methods]This study determines the petrological and geochemical characteristics of outcrop samples obtained from the Wufeng-Longmaxi shale in the southern Sichuan Basin through thin-section identification,X-ray diffraction,laser Raman spectroscopy,whole-rock asphalt reflectance,and conventional physical property analyses.The characteristics of resistivity change in the shale during deformation were analyzed through triaxial compression tests.The impacts of fracture system generation and conductive fluid intrusion on low-resistivity shale were also clarified.[Results]The results show that the resistivity of shale samples,which have similar characteristics of clay minerals,pyrite,organic matter content,and thermal maturity level,significantly decreased after saturation with brines of various salinities.A positive correlation was observed between the resistivity reduction(95.07%-98.70%)and brine salinity.After reaching the compressive strength,the resistivity reduction of the brine-saturated samples varies from 5.7 Ω·m to 25.7 Ω·m(average:13.3 Ω·m).This reduction shows a linearly positive correlation with the resistivity observed post cracking.The intrusion of conductive fluid and the generation of the fracture system in shale are the primary controlling factors for resistivity reduction.The resistivity after cracking is influenced by both the intruded saltwater salinity and fracture density.[Conclusion]This research elucidates the influence mechanism of tectonic fault zones on shale resistivity and enhances the theoretical framework for understanding the genesis of low-resistivity shale,with significant implications for the exploration and development of low-resistivity shale formations.关键词
低阻页岩/低阻成因/裂缝/地层水/四川盆地/五峰-龙马溪组/三轴压缩模拟试验Key words
low-resistivity shale/low-resistivity origin/fracture/formation water/Sichuan Basin/WuFeng-Longmaxi Fromations/triaxial compression test分类
地质学引用本文复制引用
高天,刘睿,徐璐,陈增裕,李佳明,龙思宇,廖强,刘鹏,李鹏艳..基于三轴压缩模拟试验的页岩低阻成因机制[J].地质科技通报,2025,44(2):224-237,14.基金项目
国家自然科学基金项目"五峰-龙马溪组页岩孔隙结构的构造压实调整机制研究"(42072184) （42072184）
