Numerical modeling of nitrogen injection into gas condensate reservoir


Gas-condensate reservoirs differ from dry-gas reservoirs. Gas condensate production is predominantly gas from which a quantity of liquid is condensed; the amount condensed being based on the gas-oil-ratio, GOR, in surface separators. Condensate dropout occurs in the reservoir as the pressure falls below dew-point, as a result of which, the liquid production decreases significantly and the condensate formed in the reservoir is also unrecoverable. Injection and cycling of dry natural gas has been used to enhance the condensate production from these reservoirs. However natural gas has become more valuable and alternative gases must be investigated. One of such gas is nitrogen which is inert and can be generated inexpensively at the well site.

The purpose of this research study was to develop a gas condensate reservoir model to determine the effects that nitrogen injection has on the condensate recovery. In order to build a realistic reservoir model, data from a deep high pressure gas condensate field was used. The results of this study indicated that for original well pattern, nitrogen injection did not show an overall benefit to condensate recovery. However alternative development plan for the reservoir showed increased condensate producibility and thus the viability of nitrogen injection.