Mechanism Research On Enhancing Oil Recovery Of Flooding Oil System Without Alkaline After Polymer Flooding

Polymer flooding can enhance swept volume and oil displacement efficiency, oil recovery can enhanced above 10%OOIP after polymer flooding than that of water flooding. But about 50% of the oil is remained under the ground. At the same time, reservoirs after polymer flooding are more and more after major reservoirs and the First Class oil reservoirs are developed. How to develop the reservoirs efficiently? Whether oil recovery can be enhanced farther? Researching and testing technique and exploring the way which can enhance oil recovery further is certainly facing and challenging for petroleum industry in our country. So in this paper, the experimental study of surfactant flooding and surfactant/polymer(SP) flooding after polymer flooding was progressed, displacement mechanism is discussed, the following works were finished:(1)The displacement oil experiments were finished in artificial core, the displacement oil effects of surfactant flooding and SP flooding after water flooding are analyzed with that of after polymer flooding. The probability of enhancing oil recovery of surfactant flooding and SP flooding are analyzed quantitatively after polymer flooding. The results of investigation indicate that oil recovery can be enhanced by surfactant flooding and SP flooding further after polymer flooding. But the effect of enhancing oil recovery is not obvious especially by surfactant flooding after polymer flooding, the effect of enhancing oil recovery is more obvious by SP flooding after polymer flooding.(2)The displacement oil experiments of microscopic model were progressed, the seepage flow process of different interfacial tension surfactant flooding and different viscoelasticity and interfacial tension SP flooding is acquired after polymer flooding in the dead-end model and artificial homogeneous model. The distribution of remaining oil are analyzed, startup and moving mechanism of kinds of residual oil are analyzed. The probability of enhancing oil recovery is verified further by surfactant flooding and SP flooding after polymer flooding. The results of investigation indicate that oil recovery can be enhanced further by surfactant flooding and SP flooding after polymer flooding. The advancing value of oil recovery and final oil recovery are enhanced with interfacial tension decreasing in surfactant flooding after polymer flooding. The advancing value of oil recovery and final oil recovery are enhanced with viscoelasticity of polymer raising and interfacial tension decreasing in SP flooding after polymer flooding.(3)The flowage process of polymer solution is discussed in the asymmetrical undulating tube by numerical calculation, the affect of We andαon first normal stress Tzz,first normal stress difference N1 andshear stress Trz is analyzed on the wall of asymmetrical undulating tube, the action mechanism of polymer solution on residual oil film is analyzed.