Overview of Polymer Flooding (EOR) in North Africa Fields – Elements of Designing a New Polymer/Surfactant Flood Offshore (Case Study)

摘要

When petroleum reservoirs are depleted by primary recovery mechanisms only small fractions are produced (5-30%). Implementing a secondary recovery, water flooding, would still not produce all the recoverable oil present in the reservoir due to a poor sweep efficiency as the result of bypassed or upswept oil. Use of polymer flooding increases water viscosity which controls water mobility thus improving the sweep efficiency, thus increasing the recovery factor. Many successful polymer projects have increased recoveries of 3-10%. This paper presents a case study to investigate the effectiveness of polymer and surfactant flood in Offshore Egyptian Field. This field is located in the Gulf of Suez, and the reservoir is sandstone formation with active water aquifer and has very high permeability in the order of few Darcies. The reservoir contains medium quality crude having viscosity of 17.5 - 24 cp with mobility ratio of 22 – 49 which makes it a good candidate for polymer flooding especially the reservoir has high residual oil saturation. The objective of this paper is to present an extensive review of the polymer flooding literature and what constitutes a successful polymer flood project worldwide. We performed a reservoir simulation study to investigate the effect of different parameter on the polymer flooding performance using a sector model of the field. Parameters such as polymer type, polymer solution viscosity, polymer slug size, and slug concentration will be studied to come with different scenarios for evaluation and optimization of the polymer flooding pilot. This will be a key to evaluate the polymer flooding technique in the early stage of oilfield development. Results of this paper, will present the methodology needed to design a polymer and surfactant flooding project and it will provide the steps and data needed from the core lab (related to the rock qualities) and fluid lab to calibrate and have representative reservoir simulation sensitivity runs to optimize the design. This paper will focus on a case study from North Africa to implement offshore polymer flooding.