Experimental study on the influence of fractured-vuggy porous media on condensate gas depletion production

The dew point pressure can be obtained by conventional condensate gas phase test in PVT cylinders. However, in condensate gas reservoirs, the fluid interacts with the fractured-vuggy porous media, which makes the depletion process of condensate gas in pores, fractures or vugs different from that in PVT cylinder. In order to study the mechanism of this difference, three different experimental models were made to carry out the condensate gas depletion production experiment. The results showed that the existence of fracture-vuggy porous media would affect the depletion production process. The pores, fractures and vugs increased the dew point pressure from 26.2 MPa to 26.6 MPa and decreased the condensate oil recovery from 72.8% to 70.7%. When the fractures, vugs and pores are filled with powered fine sand of carbonate rocks, the dew point pressure reaches 27.4 MPa and the condensate oil recovery reduces to 68.4%. The fractured-vuggy porous media will aggravate the retro condensation phenomenon, promote the accumulation of heavy hydrocarbon components on the pore surface and precipitate in the form of condensate oil and hinder the recovery of condensate oil. This work explains the mechanism of the influence of fractured-vuggy porous media on the phase behavior of condensate gas.