Carbon dioxide compatible non-aqueous crosslinked fracturing fluids and methods for their use
View Patent ↗Alcohol based hydraulic fracturing fluids useful for treating oil and gas wells are disclosed. The fluids are compatible with carbon dioxide, and comprise an alcohol, a polymer, a crosslinking agent, and a breaker. Hydroxypropyl guar with a molar substitution of about 1.2 to about 2.2 is identified as a presently preferred polymer.
1. A method of treating a downhole well formation, the method comprising:
providing a composition comprising hydroxypropyl guar polymer with a molar substitution of about 1.2 to about 2.2 dissolved in an alcohol solvent, a zirconium crosslinker or titanium crosslinker, and a breaker;
pumping the composition into a wellbore; and
contacting the composition and the formation.
2. The method of claim 1 , wherein the composition further comprises nitrogen gas, liquid carbon dioxide, or supercritical carbon dioxide.
3. The method of claim 1 , wherein the alcohol solvent is methanol, ethanol, 2-propanol, 1-butanol, or 2-butanol.
4. The method of claim 1 , wherein the breaker is a percarbonate, a perchlorate; a peracid, or a peroxide.
5. The method of claim 1 , wherein the breaker is sodium persulfate or encapsulated potassium persulfate.
6. The method of claim 1 , further comprising removing the composition from the formation after the contacting step.
7. The method of claim 6 , wherein the contacting and removing steps remove water from the formation.
8. The method of claim 1 , wherein the contacting step dissolves polymer materials that were present in the formation.
9. The method of claim 1 , wherein the composition further comprises a proppant.
10. The method of claim 1 , wherein the composition further comprises sand, ceramic particles, or a resin coated particle.
11. The method of claim 1 , wherein the wellbore is an oil well wellbore.
12. The method of claim 1 , wherein the wellbore is a gas well wellbore.
13. A method of treating a downhole well formation, the method comprising:
providing a composition comprising hydroxypropyl guar polymer with a molar substitution of about 1.2 to about 2.2, an alcohol solvent, a zirconium crosslinker or titanium crosslinker, carbon dioxide that is either liquid or supercritical, and a breaker;
pumping the composition into a weilbore; and
contacting the composition and the formation.
14. The method of claim 13 , wherein the carbon dioxide is liquid carbon dioxide.
15. The method of claim 13 , wherein the carbon dioxide is supercritical carbon dioxide.
16. The method of claim 1 , wherein the composition contains less than 5 weight percent water.