Analysis of geological and physical characteristics of hydrocarbon reservoir effect on the polymer flooding

Abstract

In the context of "aging" of oil fields and unstable prices for oil, enhanced oil recovery methods are becoming especially topical. At present the average global oil recovery factor (ORF) is around 35 % of the initial reserves associated with the use of secondary methods that increase the reservoir recovery rate, mainly by water injection. In such a case, some extracting companies deem it necessary to use enhanced oil recovery methods starting from the very beginning of field development. Technologies, which allow increasing the ORF, include polymer flooding whose significant advantage, in comparison with other chemical methods, is a low risk and a wide range of application. The technology involves injecting water into the reservoir with an addition of polymer to increase reservoir volumetric efficiency by increasing viscosity and water-oil mobility ratio. At present the polymer flooding method is used both at light oil fields and heavy oil fields. Polymer used in this technology can withstand high temperatures and mineralization for a long period. As a rule, polymer flooding is used either in the context of unfavorable mobility ratio in the course of water-flooding or when there is a certain degree of inhomogenuity of the reservoir when a polymer injection can help decrease water mobility in high-permeability areas by supporting oil displacement from low-permeability areas. The article reviews the main peculiarities when designing polymer injections into oil-bearing reservoirs, formulates criteria for the selection of fields and reservoirs.