Stability analysis of vertical well wall using numerical modeling in one of Iran's oil wells

Well wall stability analysis is a way to optimize the economic conditions of drilling operations in wells. In order to prevent collapse and failure in the well wall, mud pressure design must be done carefully. Well stability analysis requires more and better understanding of the stress conditions and rock mechanical properties of the formation, this is shown by using a geomechanical model appropriate to the well. Using well surveying logs, a one-dimensional geomechanical model of the well was created, which expresses The lithology status of the well is elastic coefficients, in situ stresses, stress regime, and direction of horizontal stresses. Because MDT data were available in these wells, the pore pressure was estimated with very high accuracy, which is always a very important parameter in geomechanical studies. Using the Mohr-Columb criterion and the data obtained, Stability analysis was performed on the well wall and the lowest and highest mud pressure was determined. In the next step, using ۲D FLAC software, two sections of carbonate and shale sections of the well formation were selected and a model with dimensions of ۱ m by ۱ m in It was considered and by applying the initial conditions and stresses on the sections, the created models were solved using the software. After that, by applying different flower pressures on both models, the models were examined in several cases and Stable mud pressure ranges, effective stress values and displacements for the actual pressure applied to the well were obtained.