AbstractA phase‐behavior approach to the prediction of the performance characteristics of a dissolved‐gas–drive reservoir is unique in that the problem of choosing flash, differential, or composite‐solution gas‐oil ratios and formation‐volume factors has been circumvented. Data required are a compositional analysis of the reservoir fluid, the bubble point of this fluid, and the relative‐permeability curves for the reservoir rock.Gas‐oil ratios and formation‐volume factors were calculated under conditions duplicating the performance of the reservoir. A comparison was then made between these results and those obtained by calculations involving a differential, a flash, and a composite process. A vital factor in the solution of the problem is the accuracy of the calculated equilibrium constant. Agreement within 3% was obtained when a calculated differential formation‐volume curve was compared with an experimental