Experiments on the diffusion law of dry gas injection in BZ19-6 condensate gas reservoir
The BZ19-6 condensate gas reservoir exhibits well-developed reservoir fractures and high condensate oil content.Injecting gas can improve oil recovery,but the diffusion between injected gas and the condensate oil and gas may impact the effectiveness of gas injection in enhancing recovery.Based on Fick's law,diffusion experiments were conducted on different types of rock samples(including 0.41 mD matrix core and 22 mD fractured core)from BZ19-6 condensate gas reservoir.The experiments were carried out under reservoir conditions with a temperature of 172℃ and a maximum retrograde pressure of 24 MPa to study the mass transfer and diffusion charateristics of dry gas and condensate oil/gas in different reservoir media.The results show that the diffusion coefficients between dry gas and condensate gas or condensate oil in porous media are both relatively small.The diffusion coefficient between dry gas and condensate is on the order of 10-8m2/s,while that between dry gas and condensate oil is on the order of 10-11～10-10m2/s.For different reservoir types,the diffusion coefficients in fracture cores are higher than those in matrix cores.In the Bozhong 19-6 gas condensate field,the diffusion and extraction between the injected dry gas and the condensate oil or condensate gas mainly occurs in the early stage of gas injection,with relatively low diffusion capacity.
condensate gas reservoirporous mediadiffusion coefficientdiffusion between dry gas and condensate gasdiffusion between dry gas and condensate oil
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