Hydraulic fracturing methods using cross-linking composition comprising zirconium triethanolamine complex
AssigneeE.I. duPont de Nemours and Company
InventorDonald Edward Putzig
Life of this patent
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Abstract
A method for hydraulically fracturing a subterranean formation comprises introducing into the formation a cross-linking composition which comprises a zirconium triethanolamine complex, a tetra(hydroxyalkyl)ethylenediamine, water, a cross-linkable organic polymer, and optionally, a polyol. The method can be used for cross-linking organic polymers over a wide range of pH. By varying the composition and optionally adding a delay agent, the method provides flexibility in rate of cross-linking.
Claims11
A method for fracturing a subterranean formation which comprises introducing into said formation a cross-linking composition having a pH of 3-12, at a flow rate and pressure sufficient to create, reopen and/or extend a fracture in said formation, wherein said composition comprises a zirconium triethanolamine complex, which is bistriethanolamine zirconate or tetra-triethanolamine zirconate, N,N,N′,N′-tetrakis(hydroxyisopropyl)ethylenediamine, water, a buffer, and a cross-linkable organic polymer, wherein said composition is produced by mixing the zirconium triethanolamine complex with N,N,N′,N′-tetrakis(hydroxyisopropyl)ethylenediamine, water, buffer and organic polymer, and further wherein the composition comprises from about 0.01 to about 5 moles of tetrakis(hydroxyisopropyl)ethylenediamine per mole of zirconium triethanolamine complex.
A method for fracturing a subterranean formation which comprises:
- (a) preparing a base gel by mixing a cross-linkable organic polymer with a solvent, wherein said solvent is water or a mixed water/organic solvent or an aqueous solution;
- (b) preparing a cross-linking composition by mixing a zirconium triethanolamine complex, which is bistriethanolamine zirconate or tetra-triethanolamine zirconate, N,N,N′,N′-tetrakis(hydroxyisopropyl)ethylenediamine, and water and wherein the composition comprises from about 0.01 to about 5 moles of tetrakis(hydroxyisopropyl)ethylenediamine per mole of zirconium triethanolamine complex;
- (c) contacting the base gel with the cross-linking composition;
- (d) permitting the base gel and the cross-linking composition to react to form a cross-linked aqueous gel;
- and
- (e) introducing the cross-linked gel into the formation at a flow rate and pressure sufficient to create, reopen, and/or extend a fracture in the formation
- wherein the cross-linking composition, the base gel, or both further comprise a pH buffer to provide a pH of 3-12.
A method for fracturing a subterranean formation penetrated by a wellbore which comprises:
- (a) preparing a cross-linking composition by mixing a zirconium triethanolamine complex which is bistriethanolamine zirconate or tetra-triethanolamine zirconate, N,N,N′,N′-tetrakis(hydroxyisopropyl)ethylenediamine, and water and wherein the composition comprises from about 0.01 to about 5 moles of tetrakis(hydroxyisopropyl)ethylenediamine per mole of zirconium triethanolamine complex;
- (b) preparing a base gel by mixing a cross-linkable organic polymer with a solvent, wherein the solvent is water, or mixed water/organic solvent or with an aqueous solution;
- (c) introducing the base gel into the wellbore;
- (d) simultaneously with or sequentially after, introducing the base gel into the wellbore, introducing the cross-linking composition into the wellbore;
- (e) permitting the base gel and the cross-linking composition to react to form a cross-linked aqueous gel;
- and
- (f) introducing the cross-linked gel into the formation from the wellbore at a flow rate and pressure sufficient to create, reopen, and/or extend a fracture in the formation,
- wherein the cross-linking composition, the base gel, or both further comprise a pH buffer to provide a pH of 3-12.
Dependencies are inferred from the claim text.