Experimental Study and Numerical Simulations of Synergistic Effects for Multimedium Horizontal-Well Dissolver United...

The application of single-medium fluids is relatively ineffective due to their limited functionality in heavy oil reservoirs. To compensate for the limitations of single-medium fluid injection, multimedium collaborative technologies have been proposed and have become a primary focus of research. In this paper, a series of experiments were designed and conducted on multimedium-assisted steam flooding in horizontal wells based on the heavy oil samples from the W block in Xinjiang Oil fields, China. Production, pressure, and produced fluid characteristics were studied. Results indicated that the united N₂ and foam-assisted steam flooding demonstrated the highest oil displacement efficiency and the lowest water cut in the horizontal well, at 44.6 and 88.2%, respectively. The horizontal-well dissolver united N₂ and foam-assisted steam flooding (HDNF-SF) exhibited the longest pressure stabilization period with a higher oil content in the produced fluid. Extended numerical simulations corroborated the effectiveness of HDNF-SF in heavy oil reservoirs to explore multimedium collaborative mechanisms. The HDNF-SF achieved the highest oil recovery and oil-to-steam ratio, at 43.5% and 0.35, respectively. In HDNF-SF, N₂ facilitates energy replenishment and thermal insulation; the dissolver reduces crude oil viscosity, and the foam aids in profile control by providing plugging functionality. Through the synergistic effects of these substances, HDNF-SF can prevent steam channeling, improve the displacement efficiency, enhance sweep efficiency, and ultimately increase oil recovery. These findings hold significant theoretical and practical implications for improving sweep efficiency in heavy oil reservoirs.