Impact of Stress Field on Downhole Casing in Hydraulic Fracturing: A Case Study

Fracture propagation in fracturing operations triggers a redistribution of stress fields within the affected zone, disrupting the inherent equilibrium of in-situ stresses and subsequently imposing uneven loading on the casing. To compute the loading experienced by the casing during fracturing, a mechanical model was developed based on Sneddon's and Lame's formulations, specifically focusing on the radial stress imposed on the casing through superposition effects of multi-fracture stress perturbations. The analysis utilizing this model reveals the impact of varying fracturing parameters on the downhole casing. Notably, as the number of hydraulic fracturing cracks increases, the maximum radial stress on the casing exhibits a trend of initial increase followed by a decrease. Additionally, enlarging the perforation cluster spacing is found to mitigate the maximum radial stress on the casing. A positive correlation is observed between the maximum radial stress on the casing and the operating pump pressure, suggesting that an increase in pump pressure corresponds to an augmentation in the maximum radial stress on the casing. To avert potential failure or damage to the casing due to excessive stress during fracturing operations, measures such as reducing the number of perforations and operating pump pressure and enhancing the perforation cluster spacing are advisable to mitigate the radial stress imposed on the casing.