Work

Fracture characteristics of layered rock during supercritical carbon dioxide fracturing: an experimental and thermal–hydraulic–mechanical–damage numerical study

Year: 2026

Type: article

Abstract: Rock heterogeneity and structural anisotropy exert significant influences on fracture propagation during reservoir stimulation. Focusing on layered sandstone, this study conducted supercritical carbon dioxide (SC-CO₂) fracturing experiments under different stress ratios and bedding angles and developed a coupled thermal–hydraulic–mechanical–damage (THMD) model incorporating the pressure- and temperature-dependent thermophysical properties of CO₂. The model parameters were constrained by laboratory measurements, and the simulated fracturing responses were evaluated against the experimentally observed breakdown pressures and dominant propagation patterns. The results indicate a pronounced interaction between the far-field stress and bedding planes in controlling damage-induced fracture propagation. In the absence of bedding planes, the borehole-connected high-damage paths propagate predominantly along the direction favored by the far-field stress state. In layered sandstone, favorably oriented weak bedding planes promote damage deflection and localization along the bedding, producing along-bedding or step-like propagation accompanied by secondary damage branches. At stress ratios below unity, bedding-guided propagation is more pronounced, whereas increasing the stress ratio above unity enhances cross-bedding matrix penetration. The onset of macroscopic unstable damage propagation is consequently delayed with increasing stress ratio, corresponding to a higher numerical breakdown pressure under the prescribed pressure-loading history. Increasing the borehole pressurization rate primarily accelerates the temporal evolution of damage and advances the onset of rapid damage growth, while its influence on the overall macroscopic propagation morphology is comparatively limited. These results elucidate the mechanisms by which far-field stress and bedding govern SC-CO₂ induced damage evolution, providing a mechanistic basis for optimizing stimulation in anisotropic layered reservoirs.

Source: Geothermics

DOI: 10.1016/j.geothermics.2026.103866

Authors: Guan Rong, Qinyan Qiu, Huqi Zhang, Ruichen Luo, Zuhao Lyu

Institution: Wuhan University

Language: English

Topic: Hydraulic Fracturing and Reservoir Analysis

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,220

Funder: National Natural Science Foundation of China