基于集合卡尔曼滤波的非稳态油水相对渗透率曲线计算方法

提出一种基于半迭代集合卡尔曼滤波(EnKF)的自动历史拟合方法用于非稳态油水相对渗透率曲线的计算。进行高温、低界面张力体系作用下油水相对渗透率试验,利用半迭代EnKF历史拟合方法和JBN解析法进行数据处理,研究温度、界面张力对油水相对渗透率的影响。结果表明:利用半迭代EnKF历史拟合方法和JBN解析法所得结果区别较大,但从历史拟合的角度来看,半迭代EnKF方法结果更为合理;随着温度的升高,束缚水饱和度增大,残余油饱和度降低,油相相对渗透率升高,水相相对渗透率降低,相对渗透率曲线右移;随着界面张力的降低,束缚水饱和度和残余油饱和度都降低,油水两相共渗的范围变宽;新方法将驱油机制考虑到数学模型中,得到的相对渗透率曲线更适于在油藏数值模拟、生产优化等方面应用。

A calculation method for unstable state oil-water relative permeability curve based on ensemble Kalman filter

A calculation method for unstable state oil-water relative permeability curve based on half iterative ensemble Kalman filter(EnKF) was developed.The oil-water relative permeability experiments flooded by high temperature and low interfacial tension system were done.The half iterative EnKF method and JBN method were used to calculate the oil-water relative permeability curves.The effects of temperature and interfacial tension on the oil-water relative permeability were studied.The difference of the results from the two methods is large.But the result from the iterative EnKF is more accurate in the sense of data match.Both the irreducible water saturation and oil relative permeability increase with the increase of the temperature.The residual oil saturation and water relative permeability decrease with the increase of the temperature.The relative permeability curve moves to the right.Both the irreducible water saturation and the residual oil saturation decrease with the oil-water interfacial tension decreasing.The flooding mechanisms can be considered in the mathematical model,and the relative permeability obtained from this new method is more suitable to apply in reservoir numerical simulation and production optimization.