Alkali-surfactant-polymer combination flooding (ASP flooding) is one of the main chemical EOR techniques for the significant increase of crude oil recovery in PetroChina. In this paper, the progress in field tests of ASP flooding, effects analysis and related problems in application are introduced and discussed. The development trend of ASP flooding is suggested.

Field tests of ASP flooding in PetroChina have been performed since 1994, including six pilot tests in both sandstone and conglomerate reservoirs and three industrial tests, and the incremental oil recoveries of such tests were more than 19–20%.

It is found that three factors are responsible for successful ASP flooding field tests : (1) Good performance of oil displacement agents. (2) Good profile control and oil displacement ability. (3) Reasonable well pattern and well spacing.

Side effects encountered in field tests are as follows: (1) scaling and corrosion damaged the lifting system and shorten the average pump-checking cycle accordingly. (2) Strong emulsification resulted in many liquid treatment problems such as the excess of solid particle content over the standard of water circulation and high cost of water treatment. (3)The liquid production decreased greatly.

The development trends in chemical combination flooding technique are proposed based on results of ASP flooding field tests. The strong alkali ASP flooding should be replaced by weak alkali ASP flooding or even alkali-free SP combination flooding. The application reservoir will cover from sandstone to conglomerate and carbonate, from low salinity and low temperature reservoirs to high salinity and high temperature ones, etc. The corresponding key techniques such as development of new chemical agents and advanced produced liquid treatment system should be considered in future tests and application of chemical combination flooding.

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