Study Of Synthetic Effect Of Interfacial And Rheologic Properties Of ASP Solution On Displacement Oil

As to the problem of alkali scale in ASP flooding pilots in Daqing oil field, the key factors of deciding the oil recovery in ASP flooding and relative mechanism have been revealed by physical simulation experiments and the theories analysis, and the feasibility of ASP flooding with low alkali concentration has been investigated. For pushing the ASP flooding technology thorough development, the scientific and theoretical basis and the improving direction of the technology have been provided in the study.The results show that the high alkali is advantageous to becoming the ultra low interfacial tension, but also cause the alkali scale and deep emulsion of produced liquid, and make HPAM molecular chains to roll up and decrease the viscoelasticity of ASP solution.The effect of ultra low interfacial tension of ASP solution on oil recovery in homogenous reservoirs is very obvious, but corresponding to the heterogeneity of formation in a heterogeneous reservoir, there is a critical viscosity μσ of displacing fluid. Only the apparent viscosity of ASP solution is more than the critical viscosity μσ, the ultra low IFT can play a big role in enhanced oil recovery. Moderate alkali concentration can guarantee ASP solution to have a better ability of starting middle and low permeability layers up, while the solution is able to wash the residual oil off in the swept area. The ultra low IFT is benefit for improving washing efficiency in part homogeneous area, but to a whole heterogeneous reservoir, only expending sweeping efficiency by high viscoealsticity of ASP solution is a fundamental guarantee to enhance oil recovery.In 20% well spacing distance from a injector, the adsorption of surfactant is about 80%. Namely, the effective distance of ultra low IFT in formation is very short, so its contribution on oil recovery is limited. In theory, the IFT decrease form 10^-2mN/m to 10^-3mN/m, its effect on displacing force in formation is less then 5%. Therefore, the effect of high viscoealsticity of ASP solution on oil recovery in heterogeneous reservoirs should be paid more attention then the ultra low IFT.Finally, as to application of ASP flooding in heterogeneous reservoirs, the capillary number theory has been revised by curvefitting of experimental data, and the theory of ASP flooding have been deeply perfected.