Solid zirconium-based cross-linking agent and use in oil field applications
View Patent ↗A solid zirconium cross-linking agent is prepared comprising zirconium and hydroxyalkylated ethylene diamine ligand. Use of the cross-linking agent in compositions for oil field applications such as hydraulic fracturing and plugging of permeable zones is also disclosed.
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 a hydroxyalkylated ethylenediamine in an alcohol solvent to produce a mixture wherein the zirconium complex is a tetraalkyl zirconate and the mole ratio of hydroxyalkylated ethylenediamine to zirconium is in the range of 0.5:1 to 1.5:1; (b) adding water to the mixture in an amount of 0.1 to 5.2 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 alcohol from the product of step (c) to form a granular solid zirconium cross-linking agent.
2. The process of claim 1 wherein the hydroxyalkylated ethylenediamine is selected from the group consisting of N,N,N′,N′-tetrakis -(2-hydroxypropyl)ethylenediamine and N,N,N′,N′-tetrakis-(hydroxyethyl) ethylenediamine.
3. The process of claim 1 wherein the mole ratio of hydroxyalkylated ethylenediamine to zirconium is in the range of from 0.8 to 1.2 moles of hydroxyalkylated ethylenediamine per mole of zirconium.
4. The process of claim 1 wherein water is added in an amount of 0.5 to 1.5 moles of water per mole of zirconium.
5. The process of claim 1 wherein a diluent is added to the product of step (c) or to the solid after step (d).
6. The process of claim 5 wherein the diluent is selected from the group consisting of potassium chloride, tetramethylammonium hydroxide, titanium dioxide and silicon dioxide.
7. The process of claim 6 wherein the diluent is potassium chloride or tetramethylammonium hydroxide, and is added to the product of step (c) prior to step (d).
8. The process of claim 6 wherein the diluent is titanium dioxide or silicon dioxide, and is added to the solid after step (d).
9. 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.
10. 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 (a) contacting a zirconium complex with a hydroxyalkylated ethylenediamine in an alcohol solvent to produce a mixture wherein the zirconium complex is a tetraalkyl zirconate and the mole ratio of hydroxyalkylated ethylenediamine to zirconium is in the range of 0.5:1 to 1.5:1; (b) adding water to the mixture in an amount of 0.1 to 5.2 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 alcohol from the product of step (c) to form a granular solid zirconium cross-linking agent.
11. The cross-linking composition of claim 10 wherein the aqueous liquid is selected from the group consisting of water, aqueous alcohol, and aqueous solution of a clay stabilizer.
12. The cross-linking composition of claim 10 wherein the cross-linkable organic polymer is selected from the group consisting of solvatable polysaccharides, polyacrylamides and polymethacrylamides.
13. The cross-linking composition of claim 12 wherein the cross-linkable organic polymer is a solvatable polysaccharide and is selected from the group consisting of gums, gum derivatives and cellulose derivatives.
14. The cross-linking composition of claim 13 wherein the cross-linkable organic polymer is selected from the group consisting of guar derivatives and cellulose derivatives.
15. The cross-linking composition of claim 10 wherein the hydroxyalkylated ethylenediamine is selected from the group consisting of N,N,N′,N′-tetrakis-(2-hydroxypropyl)ethylenediamine and N,N,N′,N′-tetrakis-(hydroxyethyl) ethylenediamine.
16. The process of claim 1 wherein the tetraalkyl zirconate is tetra-isopropyl zirconate, tetra-n-propyl zirconate, or tetra-n-butyl zirconate.
17. The process of claim 10 wherein the tetraalkyl zirconate is tetra-isopropyl zirconate, tetra-n-propyl zirconate, or tetra-n-butyl zirconate.