An experimental investigation of waterflooding of gas condensate reservoirs and their subsequent blowdown

Henderson, G.D., Danesh, A. and Peden, J.M., 1992. An experimental investigation of waterflooding of gas condensate reservoirs and their subsequent blowdown. J. Pet. Sci. Eng., 8: 43-58. The phase and flow behaviour of water, gas and condensate in pores at reservoir conditions have been visually investigated using glass micromodels, with the pore dimensions and pore geometry of the micromodels being varied between tests. The displacement of hydrocarbons, both above and below the dewpoint, by the advancing water was studied. The model at residual hydrocarbon saturation was depleted and the remobilisation behaviour of the trapped gas condensate phases was investigated. Preliminary core-flooding results obtained at conditions similar to the micromodel tests confirm the observed phenomena. The micromodel investigations has enabled the mechanisms of water encroachment in gas-condensate reservoirs to be visualised at pressures above and below dewpoint, and has highlighted the differences between flow in this system and the more conventional three-phase flow processes. The continuity of condensate throughout the pore space results in its efficient displacement ahead of encroaching water. Condensate recovery is strongly affected by the rate of advancing water and the distribution of condensate in the pores, with the residual gas-condensate saturation being dependant on the water advancement rate and degree of pore heterogeneity. The extent of the isolation of residual gas condensate pockets in pores determines the increase in residual hydrocarbon saturation required for gas remobilisation by depletion. This paper e explains some ambiguities in the residual hydrocarbon and its remobilisation as recently reported in literature, and the results should assist in improving our understanding of gas-condensate recovery and hence in the management of gas-condensate reservoirs.