关键词: 低界面张力二元体系, 泡沫体系, 交替注入, 提高采收率

Abstract:           In view of the typical heterogeneous block of Daqing Oilfield，core displacement experiments are carried out and study on laboratory physical simulation of surfactant/polymer-alternating-nitrogen foam flooding has been introduced by using positive rhythm heterogeneous artificial core. The injection parameters of the system are optimized and the feasibility of improving oil recovery for low interfacial tension surfactant/polymer-alternating-nitrogen foam flooding is discussed. The experimental results show that when the total injection of the oil displacement systems is kept as a fixed value, the enhancement in oil recovery is different under the condition of the same water flooding recovery with changing of the alternating way of low interfacial tension surfactant/polymer and nitrogen foam. The injection pattern of injecting 0.05 PV foam base fluid+0.05 PV N²⁺0.10 PV low interfacial tension surfactant/polymer in a single cycle with 0.20 PV cyclic injection volume and 3 alternating rounds is the optimal injection pattern. And the stage recovery is the highest under this injection pattern, which can further improve oil recovery by about 21.82% based on water flooding.

Key words: Low interfacial tension binary system, Foam system, Alternating injection, Improving oil recovery