A Review of Recent Studies on Water Shut-off Methods in Oil Wells

Excess water production is one of the main problems of oil companies, which reduce the longevity wells, increases corrosion and destruction of facilities. Also, the cost of separation, refining and disposal is a high cost for oil companies. Therefore, water shut-off operations are essential. There are various mechanical and chemical methods to solve the problem that this article reviews and examines these methods. Chemical methods as opposed to mechanical methods instead of clogging the water above or below a plug, packer or patch of the brain tube, it completely eliminates the problem of excess water production. The application of packers to direct the flow of chemicals injected into the desired layers and prevent fluid from entering the production formation, is more than the use mode independently. Polymer flooding is much more common among oil companies than other chemical methods. Polymer systems rely on chemical modification and adsorption on pores to achieve flow control. Adsorption of the polymer layer to reduce the pore radius is the main source of chemical water shut off mechanism. Synthetic polymers such as polyacrylamide and hydrolyzed polyacrylamide can reduce permeability due to their lower cost, easier access, and better performance in low water salinity conditions. Biopolymers should be used for high water salinity conditions. These polymers are not sensitive to mechanical degradation but are more expensive than synthetic polymers. The types of polymers used for this purpose have been compared. Finally, based on the characteristics of the reservoir and the economics of the operation, the appropriate polymer is selected.