Abstract: Up to now, most of heavy oil reservoirs in Liaohe oilfield have undergone steam stimulation development, some of themwith lower crude viscosity have undergone processes from transitory conventional recovery into waterflooding. However, most of theheavy oil reservoirs follow ing steam stimulation recovery appear in obvious inconsistency in vertical and horizontal producingperformance due to their serious heterogeneities.Moreover,with precipitous pressure decline and degassed crude viscositydecrease, the development effectiveness has been distinctly getting poorer. Therefore, converting available development process ofthis type of reservoirs is the most urgent situation. This paper presents the studies of the mechanism of nitrogen-foam flood forEOR,and suggests that the mechanism of nitrogen-foam flood used to regulating injection profile is proper to improve thedevelopment effectiveness of these reservoirs.In view of few tests of large-scale nitrogen-foam flood at home and abroad,suitability research of such a flood is systematically performed using numerical and physical simulation approaches.Finally, sixheavy oil blocks in Liaohe oilfield are selected to be as field operation ones based on the reservoir conditions suitable fornitrogen-foam flood given in this paper.

Key words: heavy oil, nitrogen, mechanism, numerical simulation, physical simulation