L. Cui

Applications of time-dependent pseudo-3D stress analysis in evaluating wellbore stability

Abstract Recent studies have shown that the coupled fluid-deformation effects may significantly influence stress and pore pressure distributions around the wellbore in fluid saturated porous media, as well as its stability. Therefore, the poroelastic effect must be considered in stability analysis of inclined wellbores, especially when time-dependent/delayed borehole failure is considered. However, a complicated numerical technique is required to evaluate stress and pore pressure distributions around the wellbore based on the poroelastic model. It may not be convenient to perform the aforementioned analysis of the deviated wellbore in industry applications without a computer aided engineering (CAE) software. A window based software, PBORE-3D, has been developed recently for poroelastic analysis of inclined boreholes. The applications and capabilities of PBORE-3D are described in the present paper. The poroelastic effects on the pore pressure and the stress concentration around the wellbore, and the wellbore stability, are analyzed using this friendly CAE software.

Finite element formulation and application of poroelastic generalized plane strain problems

Abstract A generalized plane strain finite element is developed for the analysis of poroelasticity problems. The validity and accuracy of the special element is demonstrated by analyzing inclined borehole problems in isotropic and transversely isotropic poroelastic materials. For the former, comparison is made with an analytical solution and the latter, with a three-dimensional finite element solution. A substantial reduction in computational effort is realized for the generalized plane strain finite element, as compared to the three-dimensional finite element. This is achieved without sacrificing the accuracy and the ability to account for the three-dimensional material anisotropy and far field stress components.