Horizontal Open Hole Gravel Pack (HOHGP) is the conventional sand control technique for offshore non consolidated reservoirs in Brazil. Gravel pack placement requirements include the design of pumping pressures inside the operational window formed by the minimum pump rate to avoid premature rat hole screen-out and maximum pump rate to avoid formation fracture. Some special projects require additional equipment to provide selective completion – External casing packers (ECP) installed at different positions along the production screen aim the isolation of certain reservoir zones. In these cases, gravel pack placement present an additional constraint – operational pump rates should be high enough to avoid alpha wave sedimentation around the packers to assure sealing after the packer inflation process. Traditionally, design criteria consider a minimum critical velocity to avoid sand deposition.
The specification of minimum flow for cleaning the ECP, and prevent the deposition of sand in the annular space can be obtained from different criteria. Two methods are proposed to analyze the problem: a constant velocity and a constant shear stress approach. The major contribution includes computational fluid dynamic simulation (CFD) of the 3D flow around the packer, using a finite volume method. The methodology based on the estimation of the local shear stresses at the interfaces, suggests less conservative numbers which allows effective gravel pack placement in selective completion projects for narrow operational windows.