Solid zirconium-based cross-linking agent and use in oil field applications
View Patent ↗A solid zirconium cross-linking agent and use in a cross-linking composition in oil field applications such as hydraulic fracturing and plugging of permeable zones. The zirconium cross-linking agent is prepared by a process comprising contacting a zirconium complex with an alkanolamine and water at particular mole ratios of alkanolamine and water to zirconium.
1. A process to prepare a solid zirconium cross-linking agent suitable for use as a cross-linking agent comprising: (a) contacting a zirconium complex with an alkanolamine in an alcohol solvent, wherein the zirconium complex is a tetraalkyl zirconate, wherein the alkanolamine is selected from the group consisting of triethanolamine, tri-n-propanolamine, tri-isopropanolamine, and diisopropanolamine, and wherein the mole ratio of alkanolamine to zirconium is 1:1; (b) adding water to the product of step (a) in an amount of 0.5 moles of water per mole of zirconium; (c) maintaining the product of step (b) for a sufficient period of time for the product to reach equilibrium; and (d) removing the solvent from the product of step (c) to form a solid zirconium cross-linking agent.
2. The process of claim 1 wherein a diluent is added to the product of step (c) or to the solid after step (d).
3. The process of claim 2 wherein the diluent is selected from the group consisting of potassium chloride, tetramethylammonium hydroxide, titanium dioxide and silicon dioxide.
4. The process of claim 2 wherein the diluent is potassium chloride or tetramethylammonium hydroxide, and is added to the product of step (c) prior to step (d).
5. The process of claim 2 wherein the diluent is titanium dioxide or silicon dioxide, and is added to the solid after step (d).
6. The process of claim 1 wherein the temperature in step (c) is about 25 to about 90° C. and the temperature in step (d) is between 50° C. and 80° C.
7. A cross-linking composition comprising (a) an aqueous liquid; (b) a buffer; (c) a cross-linkable organic polymer; and (d) a zirconium cross-linking agent, wherein the cross-linking agent is prepared by process comprising (1) contacting a zirconium complex with an alkanolamine in an alcohol solvent, wherein the zirconium complex is a tetraalkyl zirconate, wherein the alkanolamine is selected from the group consisting of triethanolamine, tri-n-propanolamine, tri-isopropanolamine, and diisopropanolamine, and wherein the mole ratio of alkanolamine to zirconium is 1:1; (2) adding water to the product of step (1) in an amount of 0.5 moles of water per mole of zirconium; (3) maintaining the product of step (2) for a sufficient period of time for the product to reach equilibrium; and (4) removing the solvent from the product of step (3) to form a solid zirconium cross-linking agent.
8. The cross-linking composition of claim 7 wherein the aqueous liquid is selected from the group consisting of water, aqueous alcohol, and aqueous solution of a clay stabilizer.
9. The cross-linking composition of claim 7 wherein the cross-linkable organic polymer is selected from the group consisting of solvatable polysaccharides, polyacrylamides and polymethacrylamides.
10. The cross-linking composition of claim 9 wherein the cross-linkable organic polymer is a solvatable polysaccharide and is selected from the group consisting of gums, gum derivatives and cellulose derivatives.
11. The cross-linking composition of claim 10 wherein the cross-linkable organic polymer is selected from the group consisting of guar derivatives and cellulose derivatives.
12. The process of claim 1 wherein the tetraalkyl zirconate is tetra-isopropyl zirconate, tetra-n-propyl zirconate, or tetra-n-butyl zirconate.
13. The process of claim 7 wherein the tetraalkyl zirconate is tetra-isopropyl zirconate, tetra-n-propyl zirconate, or tetra-n-butyl zirconate.