Design of Horizontal Polymer Injectors Requiring Conformance and Sand Control

Abstract

For the redevelopment of a heavy oil field (160 cP), polymer flooding as an EOR technique has been studied. To minimize the number of wells and still achieve significant injection rates of 500-750 m3/d in the 30m thick reservoir, horizontal wells were designed. The completion included sand screens (WWS) with outflow control devices (OCD) to maximize injection conformance. Key to the success of polymer injection at high rates is to ensure that the solution viscosity is maintained such that effective oil sweep takes place. Since EOR polymers are sensitive to mechanical shear (i.e. loss of viscosity when flown through restrictions), the completion design has been optimized by addressing the following: Shear degradation tests in lab experiments using capillaries, sand screens, OCD nozzles and reservoir cores  Assess the expected shear rates through the sand screens, the OCD nozzles and the near wellbore area, the latter is based on the Blake-Kozeny relationship and used in coreflow tests.  A nodal analysis model using the non-Newtonian fluid model was constructed to analyse the conformance benefits and optimize the OCD nozzles.The presented work indicates that horizontal polymer injectors requiring both conformance and sand control can be designed such that high injection rates can be achieved without jeopardizing the polymer viscosity.