Practical Approach to Determine Residual Gas Saturation and Gas-Water RelativePermeability

摘要

Laboratory measurement of residual saturation (Sgr) in coresamples is a matter of some debate due to the lack of acommonly accepted general method. Different protocols canlead to different values of Sgr being generated, with theassociated uncertainty for simulation input. A previouslyconducted study indicates to the authors that steady-statedisplacement and co-current imbibition are the preferredmethods to generate resevoir representative values of Sgr. Thesteady-state technique is designed to yield full-curve relativepermeability data in addition to Sgr, but it is both costly andtime-consuming. The objective of this paper is to introduce amethod that yields both Sgr and predicted water displacing gasrelative permeability data in a time-effective and cost-effectivemanner.To determine their accuracy, the relative permeabilitycurves derived from this method have been compared to thosefrom actual laboratory test results on core samples fromvarious water-driven gas reservoirs in Australia, New Zealand,SouthEast Asia and the U.S.A. The data predicted using ourmethod have also been compared to relative permeability datapredictions using correlations previously developed by otherresearchers.The data comparisons indicate that relative permeabilitycurves generated using our new (MAK) method not onlycorrelate well with laboratory-measured steady-state curves,but also more closely approximate the laboratory data thatpredictions using previously published methods.