Analysis of Deviated Wellbore Stability Using Mud Window and Numerical Modeling

One of the main problems in drilling hydrocarbon wells is the instability of the well. This problem can be reduced by determining the appropriate drilling mud weight window. The mechanical properties of the formation, the amount of pore pressure, and the direction of the main in-situ stresses are essential parameters for analyzing the stability of the borehole wall and determining the safe window of mud weight. In addition to these parameters, choosing a suitable numerical analysis method is important and should be considered. The purpose of the present study was to determine the safe window of mud weight for vertical and directional wells in UBD mode in a carbonate formation using numerical modeling of wells by FLAC software. Some wells in Iran's oil fields were selected to represent a carbonate formation for this study. A numerical model of the well was created using well survey data and calibrated using laboratory results and drilling reports. To compare the results of the numerical modeling method with the results of the analytical method, the Mohr-Coulomb failure criterion has been used. The numerical model used in this study can be used to easily and reliably determine the required safe mud window and well path. In this study, to determine the range of the mud window for this well, the pore elastic model is combined with the finite difference codes. Keywords: Borehole Wall Stability, Numerical Modeling, UBD, Carbonate Formation, Safe Mud Window, FLAC Software