Abstract: There are various combinations of pore, network and hole in carbonate reservoir. It is of great significance to understand and characterize the gas-water two phase flow in these different types of reservoirs. A multi-relaxation color-gradient lattice Boltzmann method (LBM) in adaption to the deep-reservoir condition of carbonate reservoir is proposed. Based on the method, the gas-water two phase flow behaviors for different types of carbonate reservoirs under gas accumulation process (gas displacing water) and water invasion process (water displacing gas) are revealed. The results show that, the types of residue water during gas accumulation process include water in dead-end pore, water in side of hole, water film, water in “H” shape and network shape; the types of enclosed gas during water invasion process include gas in dead-end pore, snap off gas, gas enclosed by bypass, gas in “H” shape and network shape. Because the large volume of holes, the residue water (gas accumulation process) or enclosed gas (water invasion process) of network-hole reservoir is highest compared with other two types of carbonate reservoirs. For network reservoir and pore-hole reservoir, with the change of water saturation, the gas percolation capability is fluctuated instead of linear change with water saturation. This work can be a good support for the development of micro-percolation theory and water-invasion-prediction theory for deep carbonate gas reservoir.

Key words: carbonate gas reservoir, LBM simulation, gas-water two phase flow, combination of pore network and hole, pore scale