低渗透油藏的热水驱研究

热水驱仅包括两个被加热相的流体,热水驱的主要机理是热膨胀,降低黏度,润湿相改变和油水界面张力的降低。热水驱实验使用的岩心样本取自某稠油低渗透油藏,主要是未被饱和的砂岩。实验在相同的油藏压力,不同的温度（范围在110oC以内）和不同种类的原油下进行的。对比了每个试验的最终原油采收率、残余油饱和度、束缚水饱和度、和压力降落。应用JBN方法分析了动态恒温驱替的结果,从而得到岩心的相对渗透率及低渗透砂岩中温度对油水相对渗透率的影响。结果显示在低渗透率的砂岩中使用高温热水在较高压力下驱替稠油,也有可能获得较高的采收率。在稠油体系中,原油生产的热水注入率比在中质油和超稠油要高,但是在传统稠油油藏它的价值很少被报道。另外,研究发现当岩石被加热时,油水的相对渗透率取决于温度,而残余油饱和度会降低,束缚水饱和度会增加。

Research on the hot water flooding of low-permeability reservoirs

The hot water flooding includes merely two heated phase fluids,and its primary mechanism is thermal expansion,viscosi ty decrease,wetting phase change and oil-water interfacial tension reduction.In this paper,the adopted core samples for hot water flooding experiments are selected from some heavy low-permeability reservoir,the majority of which are unsaturated sandstones.The experiment is carried out under different temperature（bound within 110 oC） and different kinds of crude oil.Through the com parison of final oil recovery ratio,residual oil saturation,irreducible water saturation and pressure drop between each experiment,and the analysis of the results of the dynamic constant temperature flooding by applying JBN method,the relative permeability of core and the impact of the temperature of low-permeability sandstone on oil/water relative permeability are obtained.The results suggest that high recovery ratio might be realized with high-temperature hot water driving heavy oil under relatively high pressure in low-permeability sandstone.The hot water injection ratio of oil development in heavy oil system is higher than that in medi um-quality oil and ultra-heavy oil,while its value in conventional heavy oil reservoir has been seldom reported.Moreover,re search indicates that when rock is heated,oil/water relative permeability depends on temperature while residual oil saturation will decrease and irreducible water saturation will increase.