关键词: 空气泡沫, 低温氧化, 数学模型, 实验拟合, 数值模拟, 敏感性分析

Abstract:

To describe movement laws and complex flooding mechanisms of air and foam during the air-foam flooding, we built a mathematical model for the air-foam flooding based on an assumption of the correlation between phases and components. This model used the mathematical model of in-situ combustion as reference and combined the processing of physicochemical parameters with an air low-temperature oxidation dynamics equation and an empirical model of the foam flooding. The present paper examined the closure of this model and proposed a solution way to corresponding numerical models. A concept model was built and the oxidation dynamics model was modified through an experimental match with the air-foam flooding, and consequently the sensitivity towards influential factors for the displacement mechanism of the low-temperature oxidation flooding was assessed in an air-foam flooding simulation. The result shows that the displacement effect is matched considerably well with the water breakthrough time during the whole experiment. The air-foam flooding characteristic of a better effect and lower cost is fit for heterogeneous reservoirs with variation coefficients between 0.7~0.8 or for positive-rhythm reservoirs in the late water flooding stage. Many methods can be beneficial to increasing the air-foam flooding effect, such as high temperature and pressure, water injection at higher position while production at lower position, switchover to the foam flooding as the moisture content reaching to 96% by the water flooding and an inverted seven-spot well pattern in the water flooding. Besides, a better flooding effect can be also achieved as the gas liquid ratio keeps between 1∶1~2∶1, the air injection rate ranges in 0.1~0.2 PV/a or the air-foam alternating-air injection pattern is applied.

Key words: air foam, low-temperature oxidation, mathematical model, experimental match, numerical simulation, sensitivity analysis