Numerical Simulation Study on Main Control Factors of Efficient Development of an Ultra-Deep Carbonate Water Drive Gas Reservoir

From traditional fossil fuels to future clean energy, natural gas is a very important bridge. Ultra-deep carbonate water-drive gas reservoir is an important part of natural gas development. Using a numerical simulator, a single well mechanism model considering the physical properties and seepage characteristics of the target ultra-deep carbonate water drive gas reservoir is established to study the influence of water body parameters, seepage parameters and fracturing measures on its development. The reservoir characteristic parameters and flow characteristic parameters suitable for the target ultra-deep gas reservoir are extracted from the existing experiments. Based on the experimental data, a single well mechanism model of the target ultra-deep carbonate gas reservoir is established using a numerical simulator. Use single well production data for production history matching, and find out the main control factors affecting the development of water drive gas reservoir in the process of history matching. Based on the historical production data of a single well, the production index of a single well in the next 10 years is predicted. The results show that for the target ultra-deep carbonate rock water flooding gas reservoir, reducing the volume of water body, reducing the velocity of water invasion, and lowering the gas-water interface are beneficial to reduce the water production rate, weaken the gas-water Jamin effect caused by water invasion, and reduce the depletion of near-wellbore pressure. After considering the high-velocity non-Darcy effect of gas, the gas production rate of gas wells decreases, while the water production rate increases, and a lot of pressure is consumed at the near-wellbore area of the gas reservoir. In this condition, it is a must to greatly reduce the bottomhole pressure of gas wells to achieve the target gas production rate. The gas-water two-phase permeability curve considering high pressure and high temperature increases both gas and water production rate, and making the historical matching results closer to the actual single well production data. Fracturing improves the gas-phase seepage capacity and alleviate the gas-water Jiamin effect in the near-wellbore area. Under the same gas production rate, the bottomhole pressure will increase significantly. But fracturing has little effect on the water production rate of the target gas well. The novelty of this study is that the mechanism model fully simulates the reserve characteristics and seepage characteristics of the target ultra-deep carbonate rock water drive gas reservoir by using experimental data considering reservoir temperature and pressure conditions. Studying the main controlling factors of the ultra-deep carbonate water-drive gas reservoir are conducive to formulating development technology policies for the efficient development of similar gas reservoirs.