无碱二元复合体系驱油机理研究

依据毛管数理论,传统观点认为界面张力越低,采收率越高,因此超低界面张力一直是评价表面活性剂界面活性的重要指标。基于并联岩心物理模拟试验研究了界面张力与提高采收率的关系,发现非均质油藏条件下低界面张力体系采收率高于超低界面张力体系。通过室内试验研究驱油体系形成乳液状态及粒径分布规律,揭示采收率与乳液粒径之间的关系。研究认为,低界面张力体系形成的乳液液滴粒径与高渗透层喉道尺寸匹配,能够有效封堵高渗透层,迫使更多注入液转向进入低渗透层,在扩大波及体积的基础上提高洗油效率,因此低界面张力体系比超低界面张力体系具有更好驱油效果。

Analysis of Oil Displacement Mechanism of Surfactant/Polymer Combinational Flooding Systems

According to capillary number theory, it is generally thought that the lower interfacial tension (IFT) between the combination flooding and oil is, the higher oil recovery is. Some physical stimulation experiments have been finished to show a kind of different phenomenon. At the same time the relationship of recovery with IFT has been studied. In physical stimulation experiments the system with low IFT could bring better oil recovery than one with ultra-low IFT in heterogeneous reservoirs. Some kinds of emulsion made by combinationSwith different IFT have been studied. The relationship between IFT and emulsion radius has been analysised. The reason why the system with low IFT could get higher oil recovery has been found. The size of emulsion of the system with low IFT is similar to pores of cores with high permeability. Emulsion could plug high permeability channels in waterflooding reservoirs. The system with low IFT has both the good displacementSefficiency and the high sweep efficiency and higher recovery could be obtained.