Method of forming temporary blocking gel containing guar derivative
View Patent ↗A high temperature blocking gel contains a blend of an aqueous fluid and carboxymethyl guar and a crosslinking agent. The gel exhibits excellent hydration capability in brines and positive viscosity generation and controls fluid loss from an oil well during drilling, completion and/or workover operations.
1. A method of forming a blocking gel within a wellbore within a subterranean formation, the method comprising the steps of:
forming an aqueous base fluid comprising between from about 40 to about 120 pounds per 1,000 gallons of carboxymethyl guar;
adding to said aqueous base fluid a heat delayed crosslinking agent to form a gelled crosslinkable fluid, the pH of the gelled crosslinkable fluid being between from about 4.0 to about 11.0; and
pumping the gelled crosslinkable fluid into a subterranean formation adjacent the wellbore
wherein the gelled crosslinkable fluid forms a barrier within the formation when the temperature in the wellbore is greater than 125° F.
2. The method of claim 1 , wherein a gel breaker is further introduced to the gelled crosslinkable fluid.
3. The method of claim 2 , wherein the gel breaker is an enzyme.
4. The method of claim 3 , wherein the gelled crosslinkable fluid is contacted with the enzyme breaker subsequent to placement of the gelled crosslinkable fluid into the subterranean formation.
5. The method of claim 1 , wherein the crosslinking agent contains zirconium.
6. The method of claim 5 , wherein the crosslinking agent is selected from the group consisting of zirconium lactate, zirconium glycolate and zirconium lactate triethanolamine.
7. A method of controlling fluid loss within a wellbore within a subterranean formation during drilling, completion and/or workover operations which comprises:
forming a gelled, aqueous base crosslinkable fluid comprising carboxymethyl guar and a crosslinking agent;
pumping the crosslinkable fluid into a subterranean formation after a drilling, completion or workover procedure; and
forming a blocking gel within the subterranean formation.
8. The method of claim 7 , wherein the pH of the base crosslinkable fluid is between from about 4.0 to about 11.0.
9. The method of claim 7 , wherein the base crosslinkable fluid contains between from about 40 to about 120 pounds per 1,000 gallons of carboxymethyl guar.
10. The method of claim 7 , wherein the crosslinking agent contains zirconium.
11. The method of claim 7 , wherein the crosslinking agent is selected from the group consisting of zirconium lactate, zirconium glycolate and zirconium lactate triethanolamine.