Fluid interface moving for the concurrent production of gas cap and oil ring of gas cap reservoirs

The pressure balance between gas cap and oil ring is likely to be broken during their concurrent production in gas cap reservoirs. In order to increase the whole development efficiency of the concurrent production of gas cap and oil ring, the Zhanzhol gas cap reservoir of Kazakhstan was taken as example to carry out the research, a three-dimensional visualization physical model was established based on the similarity criterion of oil phase, gas phase and water phase, and a reservoir engineering model of fluid interface moving rate was also set up according to the material balance principle. The calculation results of reservoir engineering model tally with the results of physical simulation experiment and reservoir dynamic test data. The moving rate template of fluid interface under three development modes, depletion development, barrier water injection development and barrier plus pattern water injection development have been also established by reservoir engineering method. The main controlling factors under different development modes have been figured out: for depletion development, the main controlling factors on the stabilization of oil-gas contact are oil recovery rate and gas recovery rate; for barrier water injection development, the main controlling factors are oil recovery rate, gas recovery rate and production-injection ratio; and for barrier plus pattern water injection development, the main controlling factors are oil recovery rate, gas recovery rate, production-injection ratio and the ratio of barrier water injection to pattern water injection.