Ternary Complex Flooding Efficiency Factors Research

The alkali/surfactant/polymer(ASP) flooding is generally considered as a new technology that not only increase sweep efficiency but also improve displacement efficiency, and that it is regarded as a very important technology in EOR process and have awarded tremendous success both in pilot test and industrialized application stages. The ASP flooding technology specialities in high cost, technological difficulty and have big risk economically. The success application of ASP flooding depend on multifarious factors, including geological feature of the reservoir and interfacial tension between oil and water and wettability as well as displacing fluids loss caused by adsorption and detention, etc.The thesis researches on the properties and synergetic effects of ASP chemical agents on the basis of the flooding mechanism of ASP flooding, and then discusses theoretically about the influencing factors of displacing efficiency in ASP flooding process. Under Daqing reservoir conditions, we research on properties of interfacial tension between five different kinds of ASP chemical system and crude oil, and screen out three kinds of chemical systems that have different order of magnitudes of interfacial tension, and then we carry out core flooding experiment both on heterogeneous and homogeneous synthetic cores and discuss about the correlation among permeability, interfacial tension, wettability and displacing efficiency in ASP processes. The result demonstrates: interfacial tension is the primary factor that improves displacing efficiency in ASP flooding; the interfacial tension between the ASP chemical system and the oil, including balance and instantaneous dynamic interfacial tension, make remarkable influence on displacing efficiency in ASP flooding process; the balance interfacial tension between oil and water falls to the level of 10^-3mN/m is only a sufficient condition but not a necessary condition for enhancing the oil recovery greatly; the wettability of the rock makes an obvious influence on saturation degree of core as well as ASP flooding efficiency. With the increase of the wetting contact angle, the displacement efficiency increases obviously in ASP flooding process; under the condition that the composition and concentration of chemical agents, the displacement efficiency is a bit higher in the core of moderate permeability.