In this study, a new approach was modified to predict the performance of water drive gas condensate reservoirs using general material balance equation. The developed model was validated using published case. The results of the developed model were compared with the published case to show that a good agreement between the developed model results and the published case. After validating the developed model against the published case, the developed model was used to analyze the production data from Yemen gas condensate reservoir to predict the performance of the selected Yemen gas condensate reservoir. The developed model used to estimate the reservoir pressure, cumulative gas production, cumulative oil production, cumulative gas trapped, water influx, oil saturation and oil and gas relative permeability. A new gas oil ratio correlation and oil formation volume factor correlation for gas condensate reservoirs were modified. To estimate the new constants of the new modified correlations of gas oil ratio and oil formation volume factor about 300 values obtained from PVT reports of gas condensate fluid samples were used.