Prediction of casing failure risk locations under multi-stage hydraulic fracturing inter-well interference in "well factory" mode

The “well factory” mode's high-density well placement and multi-stage hydraulic fracturing technology enable efficient development of unconventional oil and gas resources. However, the deployment of platform wells in the “well factory” model results in small wellbore spacing, and the stress disturbances caused by fracturing operations may affect neighboring wells, leading to inter-well interference phenomena that cause casing deformation. This study investigates the issue of inter-well interference causing casing deformation or even failure during multi-stage hydraulic fracturing in the “well factory” model, and predicts high-risk locations for casing failure. A flow-mechanics coupled geomechanical finite element model with retaining geological stratification characteristics was established. Based on the theory of hydraulic fracturing-induced rock fragmentation and fluid action leading to the degradation of rock mechanical properties, the model simulated the four-dimensional evolution of multi-well fracturing areas over time and space, calculating the disturbance in the regional stress field caused by fracturing operations. Subsequently, the stress distribution of multiple well casings at different time points was calculated to predict high-risk locations for casing failure. The research results show that the redistribution of the stress field in the fracturing area increases the stress on the casing. The overlapping fracturing zones between wells cause significant stress interference, greatly increasing the risk of deformation and failure. By analyzing the Mises stress distribution of multi-well casings, high-risk locations for casing failure can be identified. The conclusion is that the key to preventing casing failure in platform wells in the “well factory” model is to optimize the spatial distribution of fracturing zones between wells and reasonably arrange well spacing. The study provides new insights and methods for predicting casing failure in unconventional oil and gas reservoirs and offers references for optimizing drilling and fracturing designs.