Research on Key Parameters of Natural Gas Flooding Technology in Deep Low Permeability Reservoir

As the continuation of conventional reservoir development, deep low permeability reservoir has the characteristics of large reserves, deep burial and low permeability. In the process of development, the initial production is high and the production decline is fast. Conventional water flooding is difficult to form an effective displacement relationship, and new measures to enhance oil recovery are urgently needed. By comprehensive comparison of various technologies, it is feasible to carry out natural gas flooding in well group B 16–17 of Dagang Oilfield, but the minimum miscible pressure and injection pressure to achieve beneficial development are still unclear. In this paper, the minimum miscible pressure prediction model was established by using CMG Winpro phase software on the basis of fine tube experiment and empirical formula, and the minimum miscible pressure of natural gas flooding in target block was predicted to be 40.75 MPa, which greatly improved the prediction accuracy and reduced the prediction cost. On the basis of the original injection pressure prediction model, the permeability revision chart is improved, and the reason why the wellhead pressure is much higher than the stable pressure is explained that the gas phase permeability is lower than the absolute permeability in the oil-gas water three-phase flow near the well. The natural gas flooding effect of well group B 16–17 is remarkable, and the formation energy is effectively supplemented. By the end of 2022, a total of 4.297 MCM of natural gas had been injected, 5,439.61 tons of accumulated oil had been produced, and 4,281.5 tons of controlled decline had been added. Oil stability, water control and swelling and viscosity reduction are the main stimulation mechanisms of natural gas flooding, which have application potential in the 450 million ton reservoir of Dagang Oilfield.