Dual-porosity poroelastic analyses of wellbore stability

This paper presents a numerical solution of dual-porosity poroelastic formulations that couple solid deformations with fluid flow in both matrix and fracture systems of naturally fractured reservoirs. The finite element numerical method was applied to solve the inclined wellbore problem in which mud weight was considered for both permeable and impermeable boundary conditions. Failure criteria relevant to tensile, collapse, and shear failure modes were introduced into the numerical model and resulting failure areas around boreholes were subsequently defined. Several related applications, including the stability of inclined and horizontal wellbores under various in situ stress regimes, were evaluated. Upper and lower mud weight bounds and the most stable borehole orientations were determined. The best trajectory selections for horizontal boreholes were also investigated. (C) 2003 Elsevier Science Ltd. All rights reserved.