Based on the South China Sea deepwater high temperature and high pressure gas reservoir LS25 gas field, 3D geological model and a numerical reservoir model of LS25 gas field are established. Through numerical simulation of gas reservoir production, quantitative analysis of water invasion characteristics of 11 wells has been completed. The whole process of water invasion in space is as follows: bottom water conies in the early stage, forming water cone shape, the scale of the water body to the ridge increases, and the horizontal section completely emerges. Through comparative study, it is concluded that the combined water control technology of variable density screen pipe has the best water control effect. According to the prediction and analysis of the final production plan of variable density technology, it can prolong the water-free gas production period of the gas reservoir by 0.7 years, prolong the total production time by 1.9 years, increase the gas production by 1.9×108m3, and increase the recovery factor by 10.5% compared with that without water control measures. The research results are aimed to establish an optimal water control development model for buried hill gas reservoirs, and provide a good technical support for reasonable and scientific water control research of horizontal wells in offshore buried hill fractured gas reservoirs.

Based on the deep-water high temperature and high pressure LS25 gas field in the Nanhai Reservoir, through the design of heterogeneous formations and the design of water control experimental schemes, physical simulation experiments of different gas reservoir water control processes have been completed, focusing on evaluating the variable density compound water control technology based on continuous packers. In terms of the adaptability of deep-water gas reservoirs, on this basis, combined with the experiment-mine scale conversion method, a water-controlled exploitation plan for deep water high-temperature and high-pressure gas reservoirs is given. The experimental results show that: (1) Under elastic production conditions, the water body of the bottom water in the gas reservoir rises in a “progressive” manner in the initial stage, and generally develops in a “cone progression” in the middle and late stages. (2) There are obvious differences in the effects of various water control processes. A single continuous sealing body has no obvious effect on bottom water control during the gas production period of a gas well, and a single variable density screen process has no obvious effect on water control in the early stage of gas well production. The effect is good, but the risk of water channeling cannot be avoided after the gas well breaks through. The experimental effect of the variable density composite water control process based on the continuous packer is good, and the bottom water coning effect has changed to a certain extent. The experiments show that the water-free gas production period of the composite water control process is 13.7 years, the total gas production time is extended to 15.8 years, the total gas production after water control is as high as 12.37×108m3, and the recovery rate of gas wells is 9.2%, which is higher than that of elastic production. The research results aim to establish an optimal water control development model for high temperature and high-pressure deep water gas reservoirs and provide a good technical support for rational and scientific research on water control in horizontal wells of offshore deep water gas reservoirs.