Method and composition for selectively reducing permeability to water in hydrocarbon reservoirs which are hot and saline

摘要

For selectively reducing permeability to water in an underground formation producing oil and/or gas, injecting into the formation a composition comprising water, at least one water soluble aldehyde compound at a concentration (by weight) of 180 to 20,000 ppm and at least one non-ionic polysaccharide at a concentration (by weight) of 200 to 5000 ppm, the concentration of aldehyde compound being higher than that of polysaccharide. The composition may be used in the water injection well or the hydrocarbon producing well and may assist in the recovery of hydrocarbons.