Interfacial phenomena and phase behavior using alkaline-surfactant-polymer enhanced recovery methods in medium and heavy crude oils

An extensive set of physical experiments has been performed on a variety of reservoir crude oils studying the interfacial phenomena and phase behavior of alkaline surfactant polymer (ASP) systems. A platform of five reservoir crude oils was created from oil pools in southwest Saskatchewan and southeast Alberta currently producing under waterflood conditions. Crude oil quality ranged in viscosity from 198 mPa·s to 2,382 mPa·s and in density from 928 kg/m3 to 975 kg/m3. Crude oil acid numbers were measured and used to further categorize the crude oil. A simulated reservoir brine of de-ionized water and 2.0 wt% NaCl + 1.0 wt% Sec-Butyl alcohol was used during the interfacial tension and phase behavior experiments. Sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) were used as the alkaline component. A total of nine manufactured surfactants from three different suppliers were studied as the surfactant component. A low molecular weight polyacrylamide polymer was used as the polymer component of the alkaline surfactant polymer solutions. Over 3,800 interfacial tension experiments were performed using the spinning drop and Wylhemy plate methods. Phase behavior experiments were performed on high graded alkaline surfactant polymer systems for each crude oil displaying superior interfacial tension reduction results. Numerous suitable ASP systems were found for each crude oil with respect to the fluid-fluid interactions studied.