Enhanced Oil Recovery from High-Viscosity Oil Deposits by Chemically Evolving Systems
L. Altunina, V. Kuvshinov, I. Kuvshinov and L. Stasyeva
Event name: IOR 2019 – 20th European Symposium on Improved Oil Recovery
Session: Coffee Break / Poster Session Day 3
Publication date: 08 April 2019
Info: Extended abstract, PDF ( 696.54Kb )
Price: € 20
reservoir, during oil displacement effective oil-displacing liquids with a high acid-base buffer capacity controlled by viscosity are successively formed, regularly changing each other, as well as emulsion and gas-liquid systems of a colloidal dispersion degree. Presented are the results on the study of the acidic oil-displacing surfactant-based composition of prolonged action, adduct of inorganic acid and polyatomic alcohol. The interaction of the initially acid composition with the carbonate reservoir caused CO2 release, the viscosity of the oil decreased by 1.2-2.7 times, the pH of the composition increased and it chemically evolved to become an alkaline oil-displacing composition. Thus, effective oil displacement and prolonged reservoir stimulation have been ensured. The composition is compatible with mineralized formation waters, has a low freezing point (minus 20 ÷ minus 60 °C), low interfacial tension on the boundary with oil. The composition is applicable in a wide range of temperatures, from 10 to 130 °С, it proved high efficiency under field tests on the Permian-Carboniferous heavy oil deposit in the Usinsk oilfield in Russia. Within the concept of chemically evolving systems, a thickened oil-displacing composition based on surfactants, ammonium and aluminum salts and carbamide, which due to chemical evolution in the reservoir becomes simultaneously a flow deflecting and oil-displacing nanostructured system, has also been studied. In the reservoir, under thermal stimulation, the composition forms CO2, an alkaline ammonia buffer system and an aluminum hydroxide sol. As a result, the coefficients of reservoir coverage and oil recovery increase. In 2014-2015 field tests of the thickened composition were carried out in the area of thermal-steam stimulation on the Permian-Carboniferous deposit in the Usinsk oilfield in Russia. The composition was injected into 7 steam injection wells on a site with 75 producing wells. The injection volume was 80-110 m3 per well. The total effect on the site was 70 thousand tons of additionally produced oil.