Numerical Simulation Of Barite Sag In Horizontal Annular Flow

With the ever increasing global energy demand and diminishing petroleum reserves,current advances in drilling technology have resulted in numerous directional wells being drilled as operators strive to offset the ever-rising operating costs.In as much as deviated-well drilling allows drillers to exploit reservoir potential by penetrating the pay zone in a horizontal,rather than vertical fashion,it also presents conditions under which the weighting agents(such as barite)can settle out of suspension.This occurrence is what is commonly referred to as barite sag in the drilling industry.The present work is categorized into two parts: In the first part,governing equations were built inside a two dimensional horizontal pipe geometry and the finite element method(FEM)utilized to solve the equation-sets,for studying the solid concentration distribution of a solid-liquid system in pipe flow.In the second part,governing equations were built inside a three dimensional horizontal annular geometry and the finite volume method(FVM)utilized to solve the equation-sets,for studying the barite sag phenomenon in an annulus under flow conditions.The results of the first part of the simulation are the solid concentration(in both the axial and radial direction),mixture viscosity,and a prediction of the barite bed characteristics.Additionally,a comparison of the simulation results with model results in literature indicates agreement.The results of the second part of the simulation show that the highest occurrence of barite sag is at low annular velocities,non-rotating drill pipe,and eccentric drill pipe.Comparing the results of the numerical simulation,on a qualitative basis,with simulation and experimental observations reported in literature on the study of annular velocity and drill pipe rotation on dynamic barite sag in horizontal annular flow indicates closeness.The CFD approach in this study can be utilized as a research study tool in understanding and managing the barite sag problem.Additionally,against the shortcoming of the CFD approach based on the Euler-Lagrange method,a CFD-DEM approach is proposed for further research on the dynamic barite sag problem in annular flow.