Cyclic Waterflooding in Homogeneous and Layered Beadpacks

Cyclic waterflooding has received recent attention since many experimental, simulation studies and field tests have shown that it may lead to additional oil recovery. Even though the process is very similar to conventional waterflooding, there are new effects taking place under pulsed conditions. Two-phase immiscible experiments performed on homogenous and layered packed glass beads cells are compared with conventional continuous injection while doing a visualization of the displacement process. In the pulsed experiments, injection is switched on/off using a timing device in the pumping system. The effect of pack wetting condition was evaluated for the homogeneous case.<br>It is found that the amount of oil recovered at intermediate stages (1-3 PV injected water) is larger for the pulsing mode. In the homogeneous case, final recovery is the same for both injection methods within experimental error, whereas additional oil is recovered for the layered sample. In the pulsed experiments, during off injection period, spontaneous fluid spreading was observed leading to smoother displacement fronts compared to continuous injection. Also, displacement fronts were more stable under pulsed conditions. The study concludes that residual oil saturation under pulsed injection can be reached earlier than under continuous injection, a result very attractive for field application.<br>