As the challenges faced by the development of low-permeability oil fields increase,it is particularly important to adopt effective oil extraction technology to improve oil recovery and reduce development costs.In this paper,experimental methods were used to evaluate the foam stability,rheological characteristics and oil displacement efficiency of the nitrogen foam composite oil displacement system under different formation conditions.Experimental results showed that the half-life of foam was 88.5 min at 25 ℃and 101.325 kPa,which was significantly reduced to 19.9 min at 100 ℃ and 1013.25 kPa,showing obvious temperature and pressure dependence.The viscosity of the foam decreased from 1.58 Pa·s to 0.82 Pa·s when the shear rate increased from 0.1 s-1 to 10 s-1,indicating its good shear thinning behavior.In terms of oil displacement efficiency,as the injection pressure increased from 101.325 kPa to 1013.25 kPa,the oil displacement efficiency increased from 45.5% to 75.8%.In addition,biodegradation rate and toxicity testing of the foam components demonstrated its environmental friendliness,making it ideal for oilfield applications.
维普
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