1. A computer-implemented method for approximating multiphase flow reservoir production simulation, the method comprising: generating, by a computer system, a set of pseudo-phase production relative permeability curves representing a single phase of a multiphase fluid flow through a subsurface porous medium; receiving, by the computer system, production rate history data; receiving simulation configuration parameters; performing, by the computer system, flow simulation using each pseudo-phase production relative permeability curve in the set of pseudo-phase production relative permeability curves and the simulation configuration parameters; determining, by the computer system, an optimal matching pseudo-phase production simulation result that best matches the production rate history data by: interpolating pseudo-phase production rate data resulting from the flow simulation for each pseudo-phase production relative permeability curve; comparing the interpolated pseudo-phase production rate data for each pseudo-phase production relative permeability curve to the production rate history data; and selecting at least one of the pseudo-phase production relative permeability curves as the optimal matching pseudo-phase production simulation result, based on the comparison; and performing relative permeability inversion using pseudo-phase production analysis to approximate relative permeability curves describing hydraulic conductivity for the multiphase fluid flow through the subsurface porous medium, based on the optimal matching pseudo-phase production simulation result.