Dynamic experiment study on depletion development of condensategas reservoir with fracture and cave

As one of the unconventional gas reservoirs nowadays, carbonate condensate gas reservoir with fracture and cave has the characteristics of diverse pore types, deep bury, complex structure, strong reservoir heterogeneity, weak connectivity and great difference in natural energy distributed in each reservoir space. The particularity of condensate gas flowing in carbonate reservoirs is determined by the double medium reservoir properties; meanwhile, the complex phase characteristics of condensate gas in porous media further increases the difficulty of these reservoirs efficient development. Starting from the point of view of dynamic depletion development, the depletion tests have been done under different conditions such as different media, different size of aquifer, depletion rate and the connective type of fracture and cave, by using oil -rich condensate gas tested in artificial full diameter fracture-cave carbonate core. The results demonstrate that porous media has contributed to the condensate oil recovery; the recovery percent of reserves in cores with different connective type of fracture and cave is different, and the sequence as followed that connecting at the top is smallest, connecting at the bottom is largest and connecting at horizon is in the middle; the presence of aquifer is helpful for oil recovery, and the larger the aquifer size, the higher the oil recovery; the depletion rate has little effect on oil recovery; the oil recovery could be higher if the cave in the cores is filled by sand, since the porous media interface influence and resist effect caused by gravel. The study result Has certain guiding significance for developing the carbonate condensate gas reservoir with fracture and cave.