Experimental Study of Injection–Production Coupling Technique for Enhanced Oil Recovery in Mature Water Flooding Reservoirs

Water flooding is one of the most widely used secondary oil recovery methods for enhanced oil recovery (EOR). However, as a reservoir matures, excessive water production often accompanies oil production. To address this issue, the injection–production coupling technique (IPCT) has been proposed to control water production and improve oil recovery. Despite its practical application, the underlying mechanisms governing the injection–production process remain unclear. To investigate this, a transparent heterogeneous sand pack model and a visualization micro-model were employed to examine the impact of the injection–production mode on oil recovery and to uncover the mechanisms of enhanced oil recovery. The results indicate that, compared to the conventional continuous injection–production mode, both the fluid flow swept area and incremental oil recovery are significantly higher in the IPCT. Sweep efficiency improves by adjusting the injection–production streamlines and displacement directions. Notably, the oil displacement effect in the “stop injection” mode is more effective than in the “reduce injection” mode. These findings suggest that the coupling injection–production mode can efficiently recover residual oil in low permeability zones, thereby enhancing overall oil recovery.