WSO / Conformance Control
On the contrary of the polymer flood application consisting in viscosifying injection water, the principle of Water Shut-Off (WSO - production well treatment by polymers) is to solve production problems caused by early water breakthrough or reservoir fractures linked to water drive. The main purpose of WSO is thus to reduce water influx from the water producing zones in order to stimulate production from oil-bearing zones.
In a similar way, Conformance Control (CC- injection well treatment by polymers) consists in injecting polymer/gel formulations to solve water channeling problems in the reservoir (high-permeability streaks, reservoir fractures, etc.).  Therefore, the main purpose of CC is to improve reservoir conformance by a deep treatment of the thief zones from the injection well.  CC is also called “Profile Control”… In the case below, a production well is represented producing from two layers: one low-permeability oil layer and one high-permeability water layer. Due to higher mobility and permeability, water production overtakes oil production from the low-permeability zone, resulting in high-water-cut production, poor sweep efficiency and poor economics.  Well performance becomes strongly affected by water influx, and early shut-in may be expected with such a poor economics.  WSO polymer treatment enables reducing water influx from the high-permeability layer with little impact on oil permeability. The net result is a reduction of the water cut of the well sometimes along with an increase in oil production rate, if the total fluid production of the well can be maintained.