Selection of Effective Surfactant Composition to Improve Oil Displacement Efficiency in Carbonate Reservoirs with High Salinity Formation Water

The paper includes the scheme of surfactant composition selection and the approach to evaluate potential results of injection for Central-Khoreiver Uplift (CKU) fields with carbonate reservoirs. Several scenarios of surfactant composition injection were studied, using high salinity treated formation water (up to 210 g/l) without applying salinity gradient. The first step of surfactant composition selection included testing of water solution stability in formation water that is characteristic for CKU conditions. Then interfacial tension of surfactant water solution with oil was measured, as well as adsorption properties. The target values of interfacial tension were set in the range around 10-2, and not higher than 10-1 mN/m. Filtration experiments on composite core model were conducted to evaluate the efficnency of selected composition. Development and tuning of linear model for the filtration experiment matched the laboratory results. Obtained parameters are included into the sector model of field development unit, considering the conversion of one of the wells to injection of chemicals. The paper presents preliminary evaluation of technological efficiency for the selected scheme of composition injection. The approach presented in the current paper can be used to plan injection of surfactant-based compositions into carbonate formation with properties that are similar to investigated values. Applying surfactants that are compatible with high salinity formation water makes possible to use treated produced water as injection medium and it decreases the costs of mix water preparation.