Application of Key Factors Analysis and Measures Prevention of Casing Deformation -A Case Study from China

Abstract Horizontal well fracturing has become a key completion and stimulation technology for unconventional reservoirs. In reservoirs with well-developed natural fractures and faults, high-intensity reservoir stimulation significantly increases the probability of fault slip induced by artificial fractures, leading to casing deformation. To prevent casing shear deformation caused by hydraulic fracturing, numerical simulations were employed to predict casing deformation risk points and develop mitigation measures. Taking the 2H well group as a case study, a geomechanics-engineering integrated model and ant tracking technology were used to identify casing deformation risk points. The Mohr-Coulomb criterion and optimized fracturing parameters were then applied to effectively mitigate these risks. The results show that the integrated geomechanics-engineering model combined with ant tracking technology can effectively identify faults and natural fractures encountered along wellbore trajectories, predicting casing deformation risk points in the 2H well group. By utilizing the Mohr-Coulomb criterion, the critical pressure of fault activation and slip was determined to be 72.5 MPa. During the fracturing operation of the 2H well group, a "reduced displacement + reduced scale" strategy was implemented, and no casing deformation occurred during the fracturing process. A casing deformation risk prediction and prevention technology was developed, with key mitigation measures summarized as follows: (1) Avoid drilling in areas with high fault activation and slip risk; if avoidance is impossible, select locations as far from fault centers as possible. (2) Optimize wellbore parameters and adjust wellbore orientation to reduce shear stress acting on the casing, thereby mitigating deformation. (3) Optimize fracturing parameters by increasing the avoidance perforation distance, reducing single-stage fracturing pressure, and increasing stage length to effectively lower casing deformation risk. This technology effectively ensures the safety of horizontal well fracturing, enhances reservoir stimulation efficiency, and provides technical guidance for casing deformation prediction and prevention measures.