Reservoir Rock Anisotropy as the Main Factor Governing Wellbore Stability in West Salym Oilfield

Summary We present the results of the wellbore stability study performed for the West Salym oilfield with the help of the three-dimensional full coupled poroelastic modeling with mudcake dynamics taking into account. It was determined that isotropic model cannot describe the borehole behavior and the transversely-isotropic poroelastic equations were implemented into computational software. The anisotropic parameters were defined trough inversion task solution for the experimental data of core compression and then used for wellbore stability study. It was shown that vertical and inclined boreholes are stable under standard West Salym drilling conditions that is correlate with real observations. The admissible ranges of mud pressure changing without wellbore collapsing were determined. It was demonstrated that inclined borehole is more resistive against pressure drop changing than vertical.