In predicting and optimizing the performance of single and multiple wells, or complex well architecture, within a drainage or flow unit, we have favored benchmark analytical or semianalytical models. Recently, a general productivity model has been constructed and presented that allows for the performance prediction of any single- and multi-well configuration within any reservoir geometry in both isotropic and anisotropic media. Such an approximation is known to have limitations when applied to two-phase reservoir flow. This work used a numerical simulator to generate IPR's for horizontal or multibranched wells producing from a solution-gas-drive reservoir. First, a base case is considered with typical fluid, rock, and reservoir properties. Then, variations from the base case are investigated. These variations cover a wide range of fluid, reservoir, and well characteristics. The effects of numerous reservoir and fluid properties on the calculated curves are investigated. Bubblepoint pressure and reservoir depletion have a significant effect on the curves. A generalized dimensionless IPR based on nonlinear regression analysis of simulator results is developed. This IPR curve is then used to predict the performance of horizontal and multibranched wells in a solution-gas-drive reservoir combined with our productivity model. For relatively low bubblepoint pressures, the curves coalesce on Vogel's classic relationship. For higher pressures they deviate substantially.