一种新的油水相渗数学模型建立及应用——以吐哈盆地低黏油藏为例

Establishment and Application of a New Mathematical Model of Oil/Water Relative Permeability:A Case Study of Low⁃Viscosity Reservoirs in Tuha Basin

针对吐哈盆地低黏油藏油相相对渗透率初期急剧下降,高含水期后下降变缓的特点,提出了一种新的油水相渗数学模型。新模型待定参数求解简便,拟合精度较高,不仅可以描述初期急剧下降、后期下降变缓的油相相对渗透率曲线,以及弓背形水相相对渗透率曲线,还可以描述常见的“X”形油水两相相对渗透率曲线。为了应用方便,提出了新的油水相渗数学模型对应的水驱油解析法,并与Gao简化式油水相渗数学模型对比,进一步论证了油层平均含水饱和度与出口端含水饱和度的线性关系式,直接代入分流量方程中,可得到一种新的广义含水变化规律。油藏应用效果较好,可供同类油藏借鉴。

The low⁃viscosity reservoirs in the Tuha basin exhibit rapid decline of oil relatively permeability in the initial development stage and slower decline in the late development stage with high water⁃cut.This paper presents a new mathematical model of oil/water relative permeability.The new model simplifies the determination of parameters and offers a high fitting accuracy.It can describe the oil relative permeability curve and the convex water relative permeability curve,and also the common X⁃shaped oil/water two⁃phase relative permeability curve.For convenient application,the new model was configured with a corresponding water flooding analytical method,and then compared with the Gao’s simplified model of oil/water relative permeability.In this way,the linear relationship between the average water saturation of oil layer and the water saturation at the outlet end was further validated.By directly substituting this relationship into the fractional flow equation,a new generalized water cut variation pattern was derived.The actual application of this model shows good results,making it a valuable reference for similar reservoirs.