Anchoring Effect of Abandoned Oil Wells in Coal, Oil, and Gas Co-Production Areas and Its Influence on Overburden Stability

This study investigates the influence of oil well anchoring on overburden stability in coal, oil, and gas co-mining areas, combining mechanical theory and numerical simulations to systematically analyze the mechanical characteristics. First, a mechanical model of oil well anchoring was developed by considering the coupled interaction between the wellbore cement sheath and the surrounding rock, and the relationship between oil well anchoring and changes in the friction angle, cohesion, compressive strength, and Young’s modulus of the surrounding rock. Subsequently, a three-dimensional numerical simulation using FLAC3D 7.0 was conducted to analyze stress redistribution, displacement field evolution, and plastic zone distribution around the oil wells under different burial depths. The results indicate that as the burial depth increases, the peak stress around the oil wells rises from 0.37 MPa to 2.24 MPa, the displacement influence range expands from 18 m to 43 m, and the plastic zone remains confined between 0.9 m and 1.6 m. No significant stress coupling effects are observed between the well groups. These findings demonstrate that the anchoring effect of oil wells effectively regulates the stratigraphic stress field, mitigates overburden deformation, and enhances wellbore stability in coal, oil, and gas co-mining areas, providing a crucial theoretical basis and engineering reference for enhancing overburden stability in coal–oil co-mining areas.