EFFECT OF SALINITY ON SURFACTANT BEHAVIOR DURING MICELLAR / POLYMER FLOODING METHOD

Abstract

Micellar I Polymer flooding is a chemical enhanced oil recovery method which is being widely used since early 70s. It gives a remarkable recovery in the laboratory compared to other methods.

The valuable and expensive surfactants used in micellar I polymer flooding projects suffer from loss due to precipitation, cation exchange phenomena, adsorption onto reservoir rock grain surfaces and others. Such losses can render surfactant enhanced oil recovery projects very costly and uneconomical. The cost of any micellar I polymer flooding project is mainly influenced by the slug concentration, which can be controlled based on the surfactant behavior during the flooding process.

The present work concentrates on the laboratory study of the characterization of a given surfactant and its chemical behavior at different water salinities with the presence of different cations. A computer program is used to simulate the laboratory results for better understanding of the surfactant behavior. The simulated and experimental results for the used surfactant are well matched even at high salinities (100,000 ppm).

The results showed that the used surfactant consists of a mixture of anionic surfactants, which makes the surfactant suitable for use up to 40,000 ppm salinity. However, at 100,000 ppm salinity, this surfactant is less efficient. So it is recommended to pre-flush the formation with low salinity water before starting the process of surfactant flooding.

Chemical tests such as used in this study, together with other physical and displacement tests, create criteria for selecting the appropriate surfactant and provide a sound engineering judgement for determining the optimum slug concentration to be used in a specific micellar I polymer flooding project.