Polymeric gel system and use in hydrocarbon recovery
AssigneeClearwater, Inc.
InventorsKevin M. Schwartz, Kevin W. Smith, Shih-Ruey T. Chen
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Abstract
Coacervate gels having excellent shear viscosities and other properties are made with anionic or cationic polymers, a smaller amount of a surfactant having a charge opposite that of the polymer, and a hydrophobic alcohol. The Zeta Potential of the gel is maintained at an absolute value of at least 20. Optional gel promoting additives include betaines and amine oxides. A preferred gel comprises poly diallyl dimethyl ammonium chloride, a lesser amount of sodium lauryl sulfonate, and lauryl alcohol. The gels are particularly useful in well drilling fluids and well fracturing fluids.
Claims20
An aqueous gel comprising water and, by weight based on the water, (a) 0.1% to 5% of an anionic or cationic polymer, (b) a lesser amount but at least 0.01% of a surfactant having from 8 to 22 carbon atoms and a charge opposite that of said polymer, (c) from 0.001 to 5% of a hydrophobic alcohol, (d) up to 5% of an amphoteric surfactant, and (e) up to 5% of an amine oxide, said gel having a Zeta Potential of an absolute value of at least 20 millivolts.
Method of making an aqueous gel comprising adding to water 0.1% to 5%, by weight based on the water, cationic polymer and a lesser amount but at least 0.01% by weight of an anionic surfactant having from 8 to 22 carbon atoms, in the presence of 0.001% to 5% linear or branched alkyl alcohol of the general formula CMH2M+2−N(OH)N, where M is a number from 6-23, and N is 1 when M is 6-12, but where M is 13-23, N may be a number from 1 to 3, and optionally in the presence of at least one of (a) up to 5% by weight amphoteric surfactant and (b) up to 5% by weight amine oxide, the ratio of said cationic polymer to said anionic surfactant being effective to provide a Zeta Potential having an absolute value of at least 20 millivolts.
17 An aqueous gel comprising a water-soluble polymer in an amount no greater than 1% by weight, having at least one of (a) a zero shear viscosity of at least 45,000 following the zero shear viscosity extrapolation procedure of Asadi, Conway and Barree in SPE 73755 or (b) a “10/100 20/40” settling rate result at 60 minutes of no more than 8 millimeters.
18 An aqueous gel of claim 17 wherein said water-soluble polymer is cationic and is present in said gel in an amount no greater than 0.7%.
19 A well treatment fluid comprising a proppant and a gel of claim 18.
20 An aqueous gel of claim 18 including an anionic surfactant in an amount less than that of said polymer, and a small amount of a hydrophobic alcohol.
Dependencies are inferred from the claim text.