Study On Relative Permeability Curve Inversion For Surfactant-polymer Flooding

Now,reservoir engineers usually choose the explicit methods that are based on core flooding experiments to calculate relavitve permeability curve.Steady-and unsteady-state method are included.Ploymer flooding and surfactant-polymer flooding involve many complex mechanisms such as rheological property of polymer solution,the diffusion of polymer and surfactant,the adsorption of polymer and surfactant.Because of some assumptions during theoretical derivation process,the calaulation result of relative permeability curves are usually inaccurate.Numerical inversion method to calculate relative permeability curve that is based on automatic history matching principle can solve this problem.So.it is very necessary to research on numerical inversion method to calculate relative permeability curve for polymer and surfactant-polymer flooding.In this paper,a one-dimensioanl chemical flooding model is eatablished by CMG and cubic B-spline curve is choosen to be the representation model of relative permeability cueve.With LM optimization algorithm,the inversion method for chemical flooding is implementation.By the example application of polymer flooding and surfactant-polymer flooding,the reliability of numerical inversion method to obtain relative permeability curve for chemical flooding is proved.The weight ratio of injection pressure,cumulative oil production and cumulative polymer production is optimized to be 5:5:1 for polymer flooding.On the basis,the research on inversion influencing factors for polymer flooding is done.The research makes clear the relationship between the error of parameters and the error of relative permeability curves.Then based on single factor studies,the error prediction model of relative permeability curve for polymer flooding is established.The research shows that polymer viscosity,residual resistance factor and inaccessible pore volume have gerater effect on the inversiom results of water phase relative permeability cueve.Polymer diffusion coefficient and adsorption coefficient have effect on both oil and water phase relative permeability curve.The weight ratio of injection pressure,cumulative oil production,cumulative polymer production and cumulative surfactant production is optimized to be 5:5:1 for surfactantpolymer flooding.On the basis,the research on inversion influencing factors for surfactantpolymer flooding is done.And the error prediction model of relative permeability curve for surfactant-polymer flooding is established.The research shows that the influence laws of polymer viscosity,residual resistance factor,inaccessible pore volume,polymer diffusion coefficient and adsorption coefficient for surfactant-polymer flooding are basically identical with those for polymer flooding.But the influence degrees are different.The influence laws of interfacial tension and surfactant adsorption coefficient for surfactant-polymer flooding are identical but influence degrees are different.Surfactant adsorption coefficient has no effect on inversion result of relative permeability curve for surfactant-polymer flooding.