Current Developments and Remaining Challenges of Chemical Flooding EOR Techniques in China

Abstract Chemical flooding EOR techniques, mainly including polymer flooding, chemical combination flooding and foam flooding, play a crucial role in Chinese oil industry. Field tests proved that chemical flooding EOR techniques could be applied successfully in onshore reservoirs in China. Challenges were also presented as the chemical flooding EOR were applied in different reservoirs. The current developments of chemical flooding EOR techniques were introduced, the chemical flooding field tests were summarized and remaining challenges were discussed in this paper. Polymer flooding has entered into commercial applications stage. By the end of 2011, 54 industrial blocks of polymer flooding have been applied in Daqing Oilfield with 13% incremental oil recovery over water flooding in average. Ten key techniques for polymer flooding have been developed involving polymer screening and evaluation, low viscosity loss facility of injection, high performance polymer preparation and injection equipments and crafts, eccentrically-wearing inhibiting technology, separated layer injection etc. Chemical combination flooding especially ASP flooding has been studied and tested intensively in China. Six pilot and four industrial field tests of ASP flooding have been implemented. More than 20% incremental oil recovery after water flooding has been obtained. A set of techniques for combination flooding have been formed such as ASP formulation optimizing, injection allocation technology, lifting technology, chemicals monitoring of produced liquid etc. Twenty foam flooding pilot tests have been carried out in China, and sixteen of them showed good performances. Challenges of polymer flooding are mainly focused on the development of new effective polymers for specific reservoir conditions such as high salinity, high temperature, and low permeability reservoirs. The limitations of ASP flooding were known as the scaling problem and difficulty in produced liquid treatment. Challenges in foam flooding were mainly the gas finger problem usually occurred in field tests. Some progresses have been made in recent research and shown good perspectives.