SELECTION OF SURFACTANT COMPOSITIONS FOR EXTRACTION RESIDUAL OIL RESERVES IN THE CONDITIONS OF HIGH-TEMPERATURE RESERVOIRS OF THE NEOCOMIAN DEPOSITS OF THE BS GROUP FORMATIONS OF WESTERN SIBERIA

Abstract

Maintaining stable production at fields in the final stage of development requires the use of enhanced oil recovery (EOR) methods that allow the mobilization of residual oil in the reservoir. The introduction of EOR based on surfactant compositions in our country is complicated by the shortage of effective thermostable reagents, which are both expensive and difficult to access. Accordingly, the issues of their import substitution are quite acute. In this work, on the basis of available anionic surfactants and nonionic surfactants, it was possible to compose two multicomponent surfactant compositions (high- and low-concentrated) for the mobilization of residual oil in the conditions of high-temperature reservoirs of the neocomian sediments of the BS group of Western Siberia. To substantiate the the components of the composition and the method of its injection, a set of experimental physico-chemical and filtration testing methods was used. In particular, the interfacial tension, the kinetics of oil film washing, the phase behavior in the oil-watersurfactant system, as well as the pre-displacement of oil after flooding using a linear composite core model of the reservoir were determined. The developed surfactant composition is a synergistic mixture that reduces the interfacial tension at the water/oil boundary to ultra-low values (5·10–3 mN/m at 0.5 % surfactant), which makes it possible to form a low-viscosity medium phase of a type III microemulsion according to the Winsor classification and effectively solubilize oil. A method of injection of surfactant compositions is proposed, according to which a rim of sulfonated polyacrylamide (PAA) with the addition of diethanolamine is injected into the oil reservoir after surfactant edging. Analysis of the dynamics of oil displacement from the linear model of the reservoir after flooding suggested that as a result of the action of a surfactant composition with subsequent injection of a polymer solution with diethanolamine, capillary-trapped oil is first mobilized, and then film oil.