Quantitative characterization of fault damage zones in shale reservoirs: asymmetric structures and their implications for fluid flow, a case study from the Gulong Sag, Songliao basin

作者：Yongqiang Qu, Xiaocen Su, Guoliang Yan, Lei Gong, Tingjing Zhang, Chao Feng, Dongsheng Cao · 发表于：Frontiers in Earth Science · 年份：2026 · DOI：10.3389/feart.2026.1800806 · 研究领域：earthquake and tectonic studies、Hydrocarbon exploration and reservoir analysis、Seismic Imaging and Inversion Techniques

Fault damage zones serve as critical conduits for fluid migration in shale reservoirs characterized by low matrix permeability. Addressing the challenges in quantitatively characterizing fault damage zones in shale, this study takes the Gulong shale in the Songliao Basin as a case study. By integrating detailed field outcrop analysis, subsurface data validation, and quantitative statistical methods, we systematically investigate the geometric characteristics, internal fracture distribution patterns, and controlling factors of fault damage zones. The results reveal that normal fault damage zones consistently exhibit systematic asymmetry, with the hanging wall damage zone width being approximately 1.5 times greater than that of the footwall. Fracture intensity decays negatively exponentially with increasing distance from the fault core, with decay coefficients of 0.614 m −1 for Fault A and 0.175–0.183 m −1 for Fault B (R 2 = 0.48–0.58). Lithology exerts a fundamental control on fracture development, with the highest fracture density occurring in brittle shale and siltstone intervals, followed by shelly limestone, while mudstone layers are the least fractured. Mechanical stratigraphy (rock competence) strictly constrains the vertical propagation of fractures, with lengths predominantly ranging from 10 to 50 cm, rarely exceeding 70 cm. Furthermore, local structural features such as fault tips and overlapping zones significantly control the scale and heterogeneity of the damage zo...