An important method to increase the recovery of reservoirs is ASP (alkaline/surfactant/polymer) flooding to lower the IFT (interfacial tension) between the crude oil and displacing fluid to an ultra-low value (<10-3 mN/m) to increase the displacement efficiency and at the same time to increase the viscosity of the displacing fluid in order to increase the volumetric sweep efficiency. However, the alkaline in the ASP fluid makes it difficult to increase the viscosity by polymers. Therefor, experiments were performed by adding natural gas to the ASP fluid to form an ASP foam (ASPF) displacing fluid. This ASPF fluid should have the characteristics of an ultra-low IFT, high displacement efficiency and also low mobility, which should increase the volumetric sweep efficiency also.

This paper introduces the results of ASPF tests in the laboratory and field. The experimental results in the lab include the foaming ability of the ASPF, the stability of the foam, its IFT, resistance to flow in cores, the incremental recovery of cores of different heterogeneity and the relationship between incremental recovery and residual oil saturation and polymer concentration. The field results include reservoir description, well pattern, composition of the injected ASPF, injection and production conditions and problems encountered.

Good results were obtained in the field. The current recovery factor is already 65.6% OOIP. The final recovery is estimated to reach 71.3% OOIP.

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