Determination of relative permeability and recovery for North Sea gas-condensate reservoirs

Coreflood experiments on gas condensate flow behavior were conducted for tw o North Sea gas condensate reservoirs. The objectives were to investigate t he effects of rock and fluid characteristics on critical condensate saturat ion (CCS), gas and condensate relative permeabilities, hydrocarbon recovery and trapping by water injection, and incremental recovery by subsequent bl owdown. Both CCS and relative permeability were sensitive to flow rate and interfac ial tension. The results on gas relative permeability rate sensitivity sugg est that gas productivity curtailed by condensate dropout can be somewhat r estored by increasing production rate. High interfacial tension ultimately caused condensate relative permeability to decrease with increasing condens ate saturation. Condensate immobile under gas injection could be recovered by water injection, but more immediate and efficient condensate recovery wa s observed when the condensate saturation prior to water injection exceeded the CCS. Subsequent blowdown recovered additional gas, but incremental con densate recovery was insignificant.