CFD SIMULATION OF CUTTINGS TRANSPORT IN ECCENTRIC HORIZONTAL AND INCLINED ANNULUS

Abstract

This work deals with the cuttings transport in eccentric directional wellbore based on computational fluid dynamics (CFD) simulation using Ansys Fluent. Oil and gas industries have shifted to directional drilling for excessive oil exploration. Improper borehole cleaning leads to severe drilling problems that lead to permanent loss of the drilling site. The effect of wellbore inclination and eccentricity on cuttings transport is investigated for the slurry inlet velocity, rotation of drillpipe and cuttings size. The considered flow is two-phase flow primary phase is carboxymethylcellulose-bentonite solution and secondary phase is cuttings of different sizes. The Eulerian-Eulerian multiphase model has been implemented for flow through annulus along with renormalization group <i>k-&epsilon;</i> mixture turbulence model. The important findings related to the effect of eccentricity and borehole inclination on cuttings transport has been explored for various drilling parameters. The required drilling fluid velocity increases for cuttings transport as the eccentricity increases. The drillpipe rotation is more effective in cuttings transport for borehole inclination of 0 and 60 deg for <i>e</i> &#61; 0.5 as compared to <i>e</i> &#61; 0.75. The eccentricity enhances the cuttings transport in a horizontal annulus as compared to an inclined annulus. The rate in increase of axial pressure drop is more for <i>e</i> &#61; 0.5 as compared to <i>e</i> &#61; 0.75 considering drillpipe rotation.