This study presented the results of a laboratory study to investigating a method to improve sweep efficiency by application of droplet flow in alkaline flooding in heavy oil reservoirs. This included micromodel flooding tests, sandpack flooding experiments and 3D physical model study. The glass-etching micromodel tests show that the injected alkaline solution can penetrate into the oil phase and create some discontinuous water droplet inside the oil phase, and finally forms droplet flow phenomenon. Depending on the high viscosity and Jamin effect, the droplet flow tends to lower the mobility of the injected water and lead to the improvement of sweep efficiency. Droplet flow phenomenon is more obvious with the alkaline concentration increasing, and resulting in a greater improvement in sweep efficiency. A series of sandpack floods were conducted using 325 mPa·s, 2000 mPa·s, and 3950 mPa·s heavy oils to assess the effectiveness of droplet flow in alkaline flooding for enhanced heavy oil recovery. The sandpack flood results demonstrate the considerable potential for improved heavy oil recovery by alkaline flooding, and moreover, the incremental oil recovery and pressure drop have been found to increase as the alkaline concentration increases. The result obtained in 3D physical model study indicates that the sweep area can be greatly improved by the formation of droplet flow in alkaline flooding. The above results demonstrate the mechanism of droplet flow in alkaline flooding to improve sweep efficiency is the dominant mechanism for enhanced heavy oil recovery.

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