Study On The Laboratory Experiment And Numerical Simulation Of Low Tension Foam Flooding

As the interfacial tension of low tension foam can achieve ultra-low level, it can not onlycontrol the injection profile as traditional foam does, but also wash oil more effectively, and atthe same time, it can be in high temperature and high salinity condition. As a result, lowtension foam can greatly improve the sweep efficiency and oil displacement, in a word, toenhance the oil recovery in the third type of reservoirs with high temperature and salinity. Solow tension foam flooding is a widely used and very promising method. Therefore, it is ofgreat significance to study the mechanism of foam flooding further to provide theory basisand technical support for the pilot tests and large scale application in the latter.Comprehensive performance of low interfacial tension foam system is evaluated bylaboratory experiments, and optimal concentration of the low interfacial tension foam agent is0.5%. It is found that this foam system whose temperature resistance and salt toleranceperformances are good can achieve ultra-low interfacial tension and can reach a highdisplacement efficiency, which can solve the problems of enhanced foam with polymer.Besides, this foam system with greater reservoir adaptability can save economic cost andimprove economic efficiency. The distribution characteristics of low interfacial tension foamand remaining oil on the plane and longitudinal direction are studied with three-dimensionalsandpack and cemented physical models. As gas floating effect can be ignored in the earlystage of foam injection, the foam is mainly in the middle and low part of the model becausethe viscous and capillary force. Foam is distributed evenly in the model at later stage whichresults in effective blocking. Remaining oil is mainly gathered in the outlet of the model, andnear the inlet of the model, the displacement efficiency is the best. Under the charge of foamblocking and displacing, and the improvement of low tension washing oil effect and gasfloating effect, the displacement efficiency in high and low permeability zones is much better.At last, on the basis of sensitivity analysis of numerical simulation models of foamflooding，the main influencing parameters of numerical simulation for low tension foamflooding is established. The low tension foam flooding plugging affecting factors are analyzed,such as foaming agent concentration, oil saturation and injection rate through one-dimensional core flooding experiments, and the values of main influence parameters ofnumerical simulation for low tension foam flooding have been gotten. On this basis, thenumerical simulation model of low tension foam flooding is modified, and model validationresults show that the modified model can be applied to the low tension foam flooding. Basedon the modified model, a three-dimensional concept model is built according to the geologicalcharacteristics of Block Tuo2in Shengli Oil field, and then the parameters that influence thedevelopment effect is optimized. The result of optimization is: pre-slug0.04PV (1.0%lowtension foaming agent solution)+main slug0.4PV (nitrogen and0.5%low-tension foamingagent solution), gas-liquid mixture injected at a velocity of0.08PV/a and the gas-liquid ratioof1:1.