Abstract:
In this study, the effect of mechanical skin and non-Darcy skin on recovery efficiencies and production performance of dry gas and gas-condensate reservoirs are studied by single well simulation. Results from reservoir simulation runs show that mechanical skin slightly reduces the ultimate gas recovery in dry gas reservoir that have high permeability but have a moderate effect in low permeability reservoir. In gas-condensate reservoir, the mechanical skin moderately reduces the ultimate gas and condensate recoveries in high permeability reservoir but have a large effect in low permeability reservoir. Non-Darcy skin does not have an effect on the ultimate recovery in dry gas and gas-condensate reservoirs when skin factor is negative but the effect is greater when skin factor is high. Gas flow rate does not have an impact on the ultimate gas and condensate recoveries. The reservoir with negative skin factor can maintain longer production plateau period and also shorten the decline period. These effects can be observed in both dry gas and gas-condensate reservoirs. The result of the study can be used as a preliminary criterion to estimate gas recovery factor of each specific reservoir. In addition, the estimated increment in recovery factor can be used as criteria to justify the investment of stimulation in such reservoir to reduce the skin and accelerate recovery. The understanding gained from this study can be applied to other reservoirs of similar types elsewhere.
