Polyisocyanate cross-linked alkylene oxide-linear non-ionic polysaccharide reaction product
Patent 4174309 Issued on November 13, 1979. Estimated Expiration Date: 
March 20, 1998. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
March 20, 1998. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesInventorAssigneeApplicationNo. 05/888485 filed on 03/20/1978US Classes:527/302, Oxyalkylated carbohydrate166/275, Injected fluid comprises water and material other than inorganic gas166/400, Sequentially injected separate fluids (e.g., slugs)507/219, Organic component is solid synthetic resin507/936, Flooding the formation523/130, Composition for plugging pores in wells or other subterranean formations; consolidating formations in wells or cementing a well or process of preparing524/44, Hydroxyethyl528/73, Reactant contains at least one heterocyclic ring528/77Ether or thioether compound contains three or more -XH groupsExaminersPrimary: Woodberry, Edward M.Attorney, Agent or FirmInternational ClassesC08G 18/00 (20060101)C08G 18/64 (20060101) C09K 8/588 (20060101) C09K 8/58 (20060101) AbstractA method for the recovery of oil from an oil-containing subterranean formation by waterflooding employing as an injection medium an aqueous solution of a viscosifier comprising the water-soluble reaction product of an organic polyisocyanate and the addition product of an alkylene oxide and linear, non-ionic polysaccharide, said addition product having a molecular weight of at least about 100,000. According to a preferred form of the invention, a polyisocyanate cross-linked hydroxyethyl cellulose is utilized as a viscosifier to decrease the mobility ratio between the injected water and oil, thereby improving the efficiency of the waterflood. The novel viscosifiers which comprise one form of the invention are characterized by an improved resistance to the effect of divalent metal ions present in the formation as well as a thermal stability which is superior to that of the viscosifiers currently used in waterflooding operations. Aqueous solutions of the viscosifiers of the invention are characterized by viscosities which are reversible with shear rate. |
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