Abstract
Foam flooding is an effective method to control water channeling in low permeability reservoirs. However, due to injection difficulty and poor foam plugging ability encountered in the application of foam flooding in field scale, oilfield production has not achieved expected effects. Therefore, it is of great significance to carry out research on foam plugging ability and multi-cycle gas-liquid alternating fluid seepage law to improve the development effect of foam flooding.
This paper establishes a resistance factor model to evaluate foam plugging ability and analyzes sensitivity parameters. By studying the characteristics of gas phase relative permeability under multiple cycles of gas-liquid alternate injection, the reason for the difficulty of gas injection during foam flooding process is clarified from a theoretical view, and it provides an alternate strategy for adjustment of development plan.
The results show that the resistance factor has 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 parameter changes. Investigation on gas relative permeability has shown that as the number of alternate cycle increases, the relative permeability of gas phase generally decreases. At the same injection volume, gas phase relative permeability in the long-period cycle is higher than that in the short-period cycle.
