After studying zones, geological sediments, oil and water, etc. of different characteristics, an Alkaline-Surfactant-Polymer flooding formulation mainly with alkylbenzene sulfonate was screened. Pilot investigation with this formulation has been conducted with different alkali and different zones, good results have been achieved both technically and economically.[1,2]

Based on former study results,[3,4] screening of ASP formulations to further reduce the usage of surfactants and get better technical and economical results were performed. The interfacial tension behavior between oil and bio-surfactant ASP systems, emulsion characteristics, adsorption, core flooding, as well as numerical simulation, etc. were studied. After success in the laboratory study, the first Alkaline Bio-Surfactant Polymer Flooding Pilot was conducted in the north of the oil field.

Both laboratory and pilot studies showed that the Alkaline Bio-Surfactant Polymer Flooding system not only can further reduce the usage of surfactant and dynamic adsorption, but also can further reduce the ultra-low interfacial tension, extend the ultra-low interfacial tension area. Its emulsion phenomenon and chromatographic separation was not significant. After the implementation of the Alkaline Bio-Surfactant Polymer Flooding pilot, good results in terms of daily water cut decrease and incremental oil of the central well were obtained, the actual production data was better than the numerical simulation prediction.

Now, the oil recovery of the central area is 21.5% OOIP over that of water flooding, preliminary economic analyses show that the chemical cost per ton of incremental oil is less than 30$. This should be a good bio-chemical flooding method.

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