Large-scale visualized physical simulation of the occurrence and flow of condensate oil in fracture-vuggy condensate gas reservoir

The Tazhong No. 1 condensate gas reservoir in Tarim Basin shows complex storage spaces and strong heterogeneity. To intuitively assess the production performance characteristics of the condensate gas reservoir and understand the occurrence mechanism of condensate oil, an experimental device and method for visualized simulation of depletion exploitation in fracture-vuggy condensate gas reservoirs were established. The condensate oil precipitation characteristics and dynamic parameters of different reservoir types during depletion were tested. The research indicates that the condensate oil occurrence characteristics in the single-fracture-vuggy model are similar to those in the multi-fracture-vuggy model. Condensate oil that precipitates on the pore walls slides down as droplets under the influence of gravity, eventually gathering at the corners of the lower areas of the pores. Unlike porous reservoirs, fracture-vuggy condensate gas reservoirs exhibit significant retrograde vaporization during the late stages of depletion production. As the depletion rate increases, the recovery degree of condensate oil also rises. For the single-fracture-vuggy model, recovery increases by 7.68%, and for the multi-fracture-vuggy model, by 9.85%, when the depletion rate is 6 MPa/h compared to 3 MPa/h. The results of this research provide crucial insights for developing technical measures to enhance condensate oil recovery in the middle and late stages of fracture-vuggy condensate gas reservoir development.