The Seepage Law Of Air Foam Flooding And Its Application In Low Permeability Reservoirs

Air foam flooding is a development replacement method suitable for the occurrence of waterlogging in low-permeability reservoirs.However,due to problems such as injecting difficulty and poor foam blocking in the field application,oil production can not achieve the expected results.Therefore,it is of great significance to improve the development of air foam flooding by characterizing the fluid distribution of air foam flooding,conducting foam blocking capacity and multi-cycle alternating seepage law.Based on the tree bifurcation network model,this paper illustrates the reservoir fluid distribution at different displacement stages.According to the fluid phase infiltration change and the definition of resistance factor,a foam resistance factor evaluation model was established and sensitivity parameters were analyzed.By studying the changes of gas phase infiltration under multiple cycles of gas-liquid alternate injection,the reasons for difficulties in gas injection during foam flooding have been elucidated from a theoretical point of view,and solutions have been given.On this basis,the influence of various factors on the plugging capacity and the phenomenon of phase-saturation and hysteresis caused by alternate gas-liquid injection are integrated.The influence rules of the injection-production parameters on the development of the foam flooding are studied by using numerical simulation techniques and the injection scheme is optimized.The resistance model results show that the resistance factor is in an S-shaped relationship with the pore radius,a linear relationship with the liquid viscosity,an L-shaped relationship with the bubble radius,and an n-shaped relationship with the gas-liquid ratio,and the foam resistance factor is extremely sensitive to the parameter change;The study of alternate injections of the rounds shows that the relative permeability of the gas phase as a whole shows a downward trend with the increase of alternating rounds.Under the same gas injection volume,the gas phase percolation of the long period is higher than the short period;numerical simulations show that increasing the injection pressure,the injection gas-liquid ratio and the injection rate can increase the oil production,and there is an optimal alternating cycle.In accordance with the optimized injection scheme,nearly half of the injection wells in the site have been improved.