A polymer treatment based on the use of a nonionic high-molecular-weight polysaccharide has been proposed for water control in high-temperature production wells. This polymer has excellent viscosifying power in all types of reservoir brines, high shear resistance and good thermal stability. Its ability to decrease the relative permeability to brine without affecting the relative permeability to hydrocarbons is demonstrated for both matricial sandstone and limestone reservoirs.
The superiority of this polysaccharide based water control treatment over other competitive processes seems obvious as soon as the reservoir temperature exceeds 70-75°C. With specially designed additives, treatments at temperature up to 120-130°C may be proposed. Moreover, because of its high shear resistance and its strong shear-thinning behavior this polysaccharide can be pumped at high injection rates with a slight wellhead pressure increase. Shut-in times of the wells treated may thus be considerably reduced.