Regularities of Alternated Displacement of High-Viscosity Oil by Steam and Surfactant-Based Systems, Generating CO2 in s

A complex EOR technology has been developed at the Institute of Petroleum Chemistry SB RAS to<br>increase the efficiency of thermal-steam and cyclic-steam treatments of high-viscosity oil pools by<br>surfactant-based systems capable to generate СО2 and alkaline buffer solutions in situ. Presented are the<br>results of laboratory research on the effect of the concentration of oil displacing systems and slug volumes<br>on oil displacement factor under the conditions simulating thermal-steam and cyclic-steam treatments. It<br>has been determined that alternation of steam slugs and oil displacing system allows one to obtain higher<br>values of oil displacement factor as compared to thermal-steam treatment. The injection of the first system<br>slug provides the major contribution to the increase in oil displacement factor. Generalizing dependencies<br>of oil displacement factor on the accumulated volume of the system injection were deduced. Under field<br>conditions it is recommended to use surfactant-based systems at concentration of 50 %. Computer<br>programs were developed to calculate the volumes of oil displacing systems at planning pilot tests. In<br>2002-2008 pilot tests of the complex technology were carried out in oil fields of Russia and China to<br>enhance oil recovery from high-viscosity oil pools. The results of the tests are presented.