Experimental study on the mechanism and development effect of multi-gas assisted steam huff and puff process in the offshore heavy oil reservoirs

Abstract Multi-gas assisted steam huff and puff process is a relatively new thermal recovery technology for offshore heavy oil reservoirs. Some blocks of Bohai oilfield have implemented multi-gas process. However, the development mechanism still requires further study. In this paper, high-temperature high-pressure (HTHP) PVT experiments different sand pack were carried out to reveal enhanced production evaluate effect The results indicated that viscosity reduction expansion main Specifically, CO 2 easily dissolved in made it mainly play role reducing viscosity, N was characteristics small solubility good expansibility, could improve formation pressure, increase sweep volume even reduce heat loss. Meanwhile, injecting break balance component content resin saturates, aromatics asphaltene so as oil. Compared with process, increased by 2–5%. optimal water–gas ratio injection temperature 4:6 300?, respectively. suggested would wide application prospect