The Oil-Water Relative Permeability Behaviour of A Low Permeable Reservoir

ABSTRACT Much attention is now paid to the development of low permeable reservoirs. However, there is almost a dearth of literature on the study of relative permeabilities in rock samples with low permeability. Group J2S of QL Reservoir is characteristics of low porosity, low permeability and low crude oil viscosity. Oil-water relative permeabilities of QL Reservoir have been measured at two different oil/water viscosity ratios by using unsteady-state method. The experimental results showed that the oil-water relative permeabilities change with the changing of oil/water viscosity ratio. It is explained that the oil-water relative permeabilities measured at oil/water viscosity ratio close to the oil/water viscosity ratio under reservoir condition coincide with the practical situation of QL Reservoir by comparing the injection-production ratio calculated from laboratory water flooding data with the practical one. The irreducible water saturations in QL Reservoir rocks range from 27.7% to 35.8% and its average value is 31.5%. The water flooding residual oil saturations range from 11.6% to 21.7% and its average value is 14.8%. Most of the water relative permeabilities at residual oil saturations range from 0.23 to 0.50 and its average value is about 0.388. Oil-Reference and illustration at end of paper water 2-phase flowing limit ranges from 47.8% to 59.0% and its average value is about 53.7%. Moreover, the end water relative permeabilities are correlated with the air permeabilities of rock samples. That is, the bigger the air permeabilities of the rock samples, the higher the end water relative permeabilities.