CFD Simulation of the Micro-mechanism of Water Trapping Effect in Carbonate Gas Reservoirs

Water invasion is an important factor restricting the development benefit of natural gas reservoirs with water. Water trapping effect accompanied by water invasion will reduce gas well productivity, shorten the stable production period of gas reservoirs, and reduce recoverable reserves. The storage space types of carbonate gas reservoirs are complex, with developed dissolution pores and fractures, and strong heterogeneity. In this paper, six different micro pore-throat structure models are established, and CFD simulation method is used to investigate the micro-mechanism and influencing factors of water trapping in carbonate gas reservoirs at the micrometer scale. The results show that: the water trapping effect is closely related to the pore-throat structure, the water flooding speed, the heterogeneity of the throat/fracture, the water invasion channel and well pattern. For gas reservoirs with water, it is suggested that the producer should be far away from the dominant channel of water invasion and the gas production should be properly controlled to reduce the water trapping effect. The research results are of great significance for formulating reasonable development technology policies for carbonate gas reservoirs with water.