Barite Sag and Its Impact On Annular Pressure Build Up Mitigation In Producing Offshore Wells

Abstract

Abstract Among several possibilities for APB mitigation, the strategy of communicating the annulus with a formation is often considered. In this case, when pressure reaches formation fracture, fluid would be drained from the annulus and thus, the pressure would be released. This article presents a comprehensive methodology to tackle the ability of the drilling fluid to relieve pressure when this mitigation strategy is chosen. The model consists on the following iterative steps: Prediction of the solids sedimentation along the time, comprising the formation of three segregation zones; Prediction of the evolution of the permeability of the decanted layer; Prediction of the pressure evolution inside the annulus, based on PVT expressions experimentally obtained for compressible organic based drilling fluids; and Calculation of the draining process which governs pressure relief. The final package is a casing design tool which enables cost well integrity reliability.