Bulk gels for permeability reduction in fractured and matrix reservoirs

Having a high water cut reduces the economic viability of oil production. Water production increases, as less-viscous water tends to flow through high-permeability zones, leaving behind large volumes of unswept oil. Since the 1920s, different materials have been used in order to plug high-permeability thief zones. Gels are often preferred for this purpose, as they provide deeper penetration than cement or mud suspensions. Moreover, some gels reduce permeability to water more than that to oil. And can be economically feasible at low oil prices if applied correctly. This article reviews permeability reduction of several widely used inorganic and organic bulk gels, with separate discussions of their application in fractures and matrix rocks of sandstone and carbonate reservoirs. The presented information is to help with proper well treatment design.