Induced migration of ﬁnes during waterﬂooding in communicating layer-cake reservoirs
The effects of ﬁnes migration induced by injection of water with a different salinity than the reservoir brine are incorporated into the upscaling model for waterﬂooding in a layer cake reservoir with good communication between the layers. Mobilization and re-capturing of the reservoir ﬁnes may give rise to reduction of the permeability in water swept zones, which subsequently leads to the diversion of water ﬂow from the initially more permeable layers to the less permeable ones. As a result, the displacement is more even, the water cut at the producer is decreased, and the oil recovery is increased. On the other hand, more energy for the pressure drop is required to maintain a constant ﬂow rate. These effects are studied within a new upscaling model developed previously (Zhang et al., 2011). In a communicating layer cake reservoir, higher end-point mobility ratio (water to oil) leads to more crossﬂow between layers and lowers the water sweep efﬁciency. However, this ratio facilitates the ﬂuid diversion caused by the ﬁnes migration, leading to a more efﬁcient enhanced oil recovery. The positive contribution from the mobility ratio to the increased oil recovery due to ﬁnes migration seems to be limited.