稠油油田油水相对渗透率和水驱油效率研究

Study on oil and water relative permeability and water flooding efficiency in heavy oil reservoirs

南堡35-2油田是海上稠油油田,具有原油粘度高、油层岩石渗透率高、胶结疏松和非均质性严重等特点,水驱开发过程中指进现象严重,难以获得较高的水驱采收率。为了更好地了解稠油油藏水驱开发特点,为提高采收率技术决策提供依据,针对油藏地质特点和流体性质特征,利用理论分析和仪器检测评价方法,研究了稠油油藏油水相对渗透率和水驱油效率,分析了稠油油藏水驱开发动态特征。结果表明,随着原油粘度增加,岩心束缚水饱和度降低,残余油饱和度升高,油相相对渗透率降低,水相相对渗透率升高,水驱采收率降低。在相同原油粘度条件下,通过提高驱替速度来增大生产压差,可以减少指进现象发生,增加水驱无水采收率和最终采收率。

Nanpu 35-2 Oil field is an offshore heavy oil reservoir featured by high crude oil viscosity, high permeability, loose cementation and serious heterogeneity. Because of the occurrence of obvious fingering phenomenon during water flooding, high recovery rate could hardly be achieved. In order to better understand the development features of heavy oil reservoirs and to provide reference for recovery rate enhancement, geologic features and fluid properties of heavy oil reservoir are analyzed theoretically and experimentally, including oil and water relative permeability and water flooding efficiency as well as dynamic water flooding performances. Analysis results indicate that with the increment of crude oil viscosity, the core irreducible water saturation, oil phase relative permeability and water flooding efficiency would decrease whereas residual oil saturation and water phase relative permeability would increase. If under the same crude oil viscosity, fingering phenomenon could be reduced through promoting displacement velocity to enlarge production pressure differentials, in order to reach the goal of enhancing water free recovery rate and final recovery rate.