Repairing wellbore cement structures and related compositions
A self-healing cement structure may be used for repairing defects. An example method of using such a cement structure includes: providing a cement structure in a wellbore, wherein the cement structure includes: a cement and elastomer particles at 1% by weight of the cement (bwoc) to 25% bwoc; applying heat to the cement structure to heat at least a portion of the elastomer particles above a melting point of an elastomer of the elastomer particles to cause at least a portion of the elastomer to melt and infiltrate into a defect in the cement structure; and allowing the elastomer to cool below the melting point of the elastomer to yield a repaired cement structure.
1 . A method comprising:
pumping a cement slurry to a location within a wellbore, wherein the cement slurry comprises: a cement precursor material, water at 40% by weight of the cement (bwoc) to 200% bwoc, and 1% bwoc to 25% bwoc of elastomer particles, and wherein the location has a static temperature that is less than a melting point of an elastomer of the elastomer particles; and
curing the cement slurry to form a cement structure at the location in the wellbore wherein the heat within the wellbore heats at least a portion of the elastomer particles above a melting point of an elastomer of the elastomer particles to cause at least a portion of the elastomer to melt and infiltrate into a defect in the cement structure.
2 . The method of claim 1 , wherein the location is an annulus between a tubular and a wellbore.
3 . The method of claim 1 , wherein the cement slurry further comprises: 30% by weight of the cement (bwoc) to 70% bwoc of a crystalline silica, 1% bwoc to 100% bwoc of a weighting agent, 0.1% bwoc to 5% bwoc of a retarder, 0.1% bwoc to 5% bwoc of a viscosifier, and 0.1% bwoc to 10% bwoc of a fluid loss control agent.
4 . The method of claim 1 , wherein the cement structure has a compressive strength of 2000 pounds per square inch (psi) to 4000 psi.
5 . The method of claim 1 , wherein the elastomer comprises one or more compositions selected from the group consisting of: poly(acrylonitrile), poly(6-aminocaproic acid), poly(trans-butadiene), poly(l-butene), poly(caprolactam), poly(decamethylene adipamide), poly(decamethylene sebacamide), poly(hexamethylene adipamide), poly(hexamethylene sebacamide), poly(hexamethylene suberamide), poly(w-undecanamide), poly(etheretherketone), poly(ethylene adipate), poly(ethylene oxide), poly(ethylene terephthalate), poly(ethylene), poly(methyl methacrylate), poly(methylene oxide), poly(4-methylpentene), poly(propylene), poly(styrene), poly(tetramethylene oxide), poly(trans-1,4-butadiene), poly(vinyl alcohol), poly(vinyl chloride), poly(vinyl fluoride), poly(vinylidene chloride), poly(vinylidene fluoride), and any combination thereof.
6 . The method of claim 1 , wherein the elastomer particles have a weight average diameter of 0.1 micron to 1 millimeter (mm).
7 . The method of claim 1 , further comprising:
applying heat to the cement structure to heat at least a portion of the elastomer particles above a melting point of an elastomer of the elastomer particles to cause at least a portion of the elastomer to melt and infiltrate into a defect in the cement structure; and
allowing the elastomer to cool below the melting point of the elastomer to yield a repaired cement structure.
8 . The method of claim 7 , wherein the applying of the heat comprises:
positioning a heater within the wellbore at or near the cement structure; and
causing the heater to apply the heat.
9 . The method of claim 8 , wherein the heater is a mineral insulated heater, a Currie heater, or a thermite heater.
10 . The method of claim 8 , wherein the positioning of the heater uses a wireline.
11 . The method of claim 8 , wherein the positioning of the heater uses a coiled tubing.
12 . The method of claim 7 , wherein the applying of the heat comprises:
moving a heater along the wellbore at or near the cement structure; and
causing the heater to apply the heat while moving the heater.
13 . The method of claim 7 , wherein the repaired cement structure has a compressive strength of 1500 pounds per square inch (psi) or greater.
14 . The method of claim 7 , wherein the defect is a crack.
15 . The method of claim 7 , wherein the defect is a microannulus.