The Determination Of The Relative Permeability Curve For SP Systems

The relative permeability curve can be used to predict the rate of oil production,calculate the water cut, estimate the reservoir wettability, and calculate the ultimate recovery,which is the indispensable parameter in oilfield development calculation, productionperformance prediction and reservoir numerical simulation. The determination of the relativepermeability curve of SP system still exist some difficulties. On the one hand, the adsorptionand retention of the SP solution in the pores result in reducing the effective viscosity ofsolution, and on the other hand, the emulsification of polymer and surfactant compoundsystem makes the calculation precision to be improved. The relative permeability curves weredetermined through the steady-state method, according to the industry standard ofSY/T5345-2007《Method for the determination of relative permeability of two-phase fluid inrocks》.The rheological properties of the SP solution were determined to calculate the effectiveviscosity of the solution in the pores. The experiment selected a set of typical data to calculatethe effective viscosity of the solution, and the result shows that, with the flow velocity of SPsolution increasing, the shear rate was increased which lead to reduce the effective viscosityof the SP solution.The relative permeability curves were determined and studied through different injectionsystems, different core permeability, different core wettability and the same concentration ofdifferent polymer molecular weight and the same viscosity of different polymer molecularweight, the results show that, under the same water saturation, the water phase relativepermeability of oil-water system was higher, and the water phase relative permeability of SPsystem was lower, and with polymer molecular weight increasing, the water phase relativepermeability reduced, and the residual oil saturation decreased under the condition of thesame concentration or the same viscosity. The relative permeability of oil phase inwater-damp porous medium was bigger than in oil-damp porous medium, and the relativepermeability of SP phase was lower, the equal-permeability point moved to the rightobviously, and the saturation of residual oil reduced gradually. The experiment of thesteady-state method will not only provide parameters for reservoir numerical simulation, butalso predict the effect of the polymer and surfactant compound system flooding to guidecompound flooding pilot test.