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Article

Stress-Barrier-Responsive Diverting Fracturing: Thermo-Uniform Fracture Control for CO2-Stimulated CBM Recovery

1
Petro China Coalbed Methane Co., Ltd., Beijing 100020, China
2
China United Coalbed Methane National Engineering Research Center Co., Ltd., Beijing 100095, China
3
National Engineering Research Center for Oil & Gas Drilling and Completion Technology, School of Petroleum Engineering, Yangtze University, Wuhan 430100, China
*
Author to whom correspondence should be addressed.
Processes 2025, 13(9), 2855; https://doi.org/10.3390/pr13092855
Submission received: 31 July 2025 / Revised: 24 August 2025 / Accepted: 26 August 2025 / Published: 5 September 2025
(This article belongs to the Special Issue Coalbed Methane Development Process)

Abstract

Chinese coalbed methane (CBM) reservoirs exhibit characteristically low recovery rates due to adsorbed gas dominance and “three-low” properties (low permeability, low pressure, and low saturation). CO2 thermal drive (CTD) technology addresses this challenge by leveraging dual mechanisms—thermal desorption and displacement to enhance production; however, its effectiveness necessitates uniform fracture networks for temperature field homogeneity—a requirement unmet by conventional long-fracture fracturing. To bridge this gap, a coupled seepage–heat–stress–fracture model was developed, and the temperature field evolution during CTD in coal under non-uniform fracture networks was determined. Integrating multi-cluster fracture propagation with stress barrier and intra-stage stress differential characteristics, a stress-barrier-responsive diverting fracturing technology meeting CTD requirements was established. Results demonstrate that high in situ stress and significant stress differentials induce asymmetric fracture propagation, generating detrimental CO2 channeling pathways and localized temperature cold islands that drastically reduce CTD efficiency. Further examination of multi-cluster fracture dynamics identifies stress shadow effects and intra-stage stress differentials as primary controlling factors. To overcome these constraints, an innovative fracture network uniformity control technique is proposed, leveraging synergistic interactions between diverting parameters and stress barriers through precise particle size gradation (16–18 mm targeting toe obstruction versus 19–21 mm sealing heel), optimized pumping displacements modulation (6 m3/min enhancing heel efficiency contrasted with 10 m3/min improving toe coverage), and calibrated diverting concentrations (34.6–46.2% ensuring uniform cluster intake). This methodology incorporates dynamic intra-stage adjustments where large-particle/low-rate combinations suppress toe flow in heel-dominant high-stress zones, small-particle/high-rate approaches control heel migration in toe-dominant high-stress zones, and elevated concentrations (57.7–69.2%) activate mid-cluster fractures in central high-stress zones—collectively establishing a tailored framework that facilitates precise flow regulation, enhances thermal conformance, and achieves dual thermal conduction and adsorption displacement objectives for CTD applications.
Keywords: CBM; fracture networks; hydraulic fracturing; stress barriers; CO2 thermal drive CBM; fracture networks; hydraulic fracturing; stress barriers; CO2 thermal drive

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MDPI and ACS Style

Zhen, H.; Gao, E.; Li, S.; Ge, T.; Wei, K.; Liu, Y.; Wang, A. Stress-Barrier-Responsive Diverting Fracturing: Thermo-Uniform Fracture Control for CO2-Stimulated CBM Recovery. Processes 2025, 13, 2855. https://doi.org/10.3390/pr13092855

AMA Style

Zhen H, Gao E, Li S, Ge T, Wei K, Liu Y, Wang A. Stress-Barrier-Responsive Diverting Fracturing: Thermo-Uniform Fracture Control for CO2-Stimulated CBM Recovery. Processes. 2025; 13(9):2855. https://doi.org/10.3390/pr13092855

Chicago/Turabian Style

Zhen, Huaibin, Ersi Gao, Shuguang Li, Tengze Ge, Kai Wei, Yulong Liu, and Ao Wang. 2025. "Stress-Barrier-Responsive Diverting Fracturing: Thermo-Uniform Fracture Control for CO2-Stimulated CBM Recovery" Processes 13, no. 9: 2855. https://doi.org/10.3390/pr13092855

APA Style

Zhen, H., Gao, E., Li, S., Ge, T., Wei, K., Liu, Y., & Wang, A. (2025). Stress-Barrier-Responsive Diverting Fracturing: Thermo-Uniform Fracture Control for CO2-Stimulated CBM Recovery. Processes, 13(9), 2855. https://doi.org/10.3390/pr13092855

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