Mitigating lost circulation

1. A method comprising:

placing a eutectic metal alloy with a coiled tubing into a wellbore formed in a subterranean formation, the eutectic metal alloy comprising a plurality of metals, the eutectic metal alloy having a melting temperature that is less than a melting temperature of each individual metal of the plurality of metals, the eutectic metal alloy comprising particles and suspended in a carrier fluid comprising a polymer and a crosslinking agent, the crosslinking agent configured to crosslink the polymer in response to exposure to a specified downhole temperature;

heating the eutectic metal alloy to a temperature equal to or greater than the melting temperature of the eutectic metal alloy to liquefy the eutectic metal alloy;

flowing the liquefied eutectic metal alloy from the wellbore and into the subterranean formation, thereby exposing the liquefied eutectic metal alloy to the specified downhole temperature within the subterranean formation and causing the liquefied eutectic metal alloy to solidify to form a seal comprising the solidified eutectic metal alloy distributed across a crosslinked polymer matrix; and

preventing, by the seal, fluid from flowing from the wellbore and into the subterranean formation.

2. The method of claim 1 , wherein heating the eutectic metal alloy comprises placing a cable heater coupled to the coiled tubing at a downhole location within the wellbore and providing power to the cable heater, wherein the cable heater comprises:

a heating element configured to generate heat in response to receiving power;

an insulation layer surrounding the heating element, the insulation layer comprising magnesium oxide; and

a sheath surrounding the insulation layer, the sheath comprising steel.

3. The method of claim 2 , comprising:

prior to placing the eutectic metal alloy with the coiled tubing into the wellbore, positioning a bridge plug or packer downhole of the downhole location within the wellbore; and

after positioning the bridge plug or packer and prior to placing the eutectic metal alloy with the coiled tubing into the wellbore, sealing the bridge plug or packer against an inner wall of the wellbore, thereby preventing fluid from flowing further downhole past the bridge plug or packer.

4. The method of claim 3 , wherein the eutectic metal alloy has a density in a range of from about 8.0 g/cm 3 to about 11.0 g/cm 3 .

5. The method of claim 4 , wherein the particles of the eutectic metal alloy have an average particle size in a range of from about 1 micrometer to about 0.25 centimeters.

6. The method of claim 5 , wherein the liquefied eutectic metal alloy has a viscosity in a range of from about 1 centipoise (cP) to about 10 cP.

7. The method of claim 6 , wherein the eutectic metal alloy is suspended in a carrier fluid comprising bentonite clay.

8. A system comprising:

a coiled tubing disposed in a wellbore formed in a subterranean formation, the coiled tubing configured to flow a lost circulation fluid;

the lost circulation fluid configured to seal a lost circulation zone at a downhole location in the subterranean formation, the lost circulation fluid comprising:

a eutectic metal alloy comprising a plurality of metals, the eutectic metal alloy having a melting temperature that is less than a melting temperature of each metal of the plurality of metals, the eutectic metal alloy configured to liquefy in response to being heated to a temperature equal to or greater than the melting temperature of the eutectic metal alloy; and

a carrier fluid comprising a polymer and a crosslinking agent, wherein the eutectic metal alloy is suspended in the carrier fluid, wherein the eutectic metal alloy, in a liquefied state in response to being heated to the temperature equal to or greater than the melting temperature of the eutectic metal alloy, is configured to flow from the wellbore and into the subterranean formation, wherein the crosslinking agent is configured to crosslink the polymer in response to exposure to a specified downhole temperature to form a seal comprising the eutectic metal alloy distributed across a crosslinked polymer matrix, wherein the seal is configured to prevent fluid from flowing from the wellbore and into the subterranean formation; and

a cable heater coupled to the coiled tubing flowing the lost circulation fluid, the cable heater located at the downhole location, wherein the cable heater is configured to, in response to receiving power at the downhole location, heat the eutectic metal alloy to the temperature equal to or greater than the melting temperature of the eutectic metal alloy to liquefy the eutectic metal alloy.

9. The system of claim 8 , wherein the cable heater comprises:

a heating element configured to generate heat in response to receiving power;

an insulation layer surrounding the heating element, the insulation layer comprising magnesium oxide; and

a sheath surrounding the insulation layer, the sheath comprising steel.

10. The system of claim 9 , comprising a bridge plug or packer positioned downhole of the downhole location within the wellbore, the bridge plug or packer sealed against an inner wall of the wellbore to prevent fluid from flowing further downhole past the bridge plug or packer.

11. The system of claim 10 , wherein the eutectic metal alloy has a density in a range of from about 8.0 grams per cubic centimeter (g/cm 3 ) to about 15.0 g/cm 3 .

12. The system of claim 11 , wherein the density of the eutectic metal alloy is in a range of from about 8.0 g/cm 3 to about 11.0 g/cm 3 .

13. The system of claim 12 , wherein the eutectic metal alloy comprises particles having an average particle size in a range of from about 1 micrometer to about 0.25 centimeters.

14. The system of claim 13 , wherein the liquefied eutectic metal alloy has a viscosity in a range of from about 1 centipoise (cP) to about 10 cP.

15. The system of claim 14 , wherein the viscosity of the liquefied eutectic metal alloy is less than 5 cP.

16. The system of claim 14 , wherein the carrier fluid comprises bentonite clay.

17. The system of claim 14 , wherein the polymer comprises hydroxyethyl cellulose.

18. A method comprising:

positioning a packer within a wellbore formed in a subterranean formation;

expanding the packer to seal against an inner wall of the wellbore, thereby preventing fluid from flowing past the packer;

flowing a lost circulation fluid through a coiled tubing into the wellbore, the lost circulation fluid comprising:

a eutectic metal alloy comprising a plurality of metals, the eutectic metal alloy having a melting temperature that is less than a melting temperature of each individual metal of the plurality of metals; and

a carrier fluid comprising hydroxyethyl cellulose and a crosslinking agent, wherein the eutectic metal alloy is suspended in the carrier fluid;

placing a cable heater coupled to the coiled tubing at a downhole location within the wellbore up hole of the expanded packer;

after placing the cable heater at the downhole location, providing power to the cable heater, thereby heating the eutectic metal alloy to a temperature greater than the melting temperature of the eutectic metal alloy to liquefy the eutectic metal alloy;

flowing the liquefied eutectic metal alloy with the carrier fluid from the wellbore and into the subterranean formation, thereby exposing the carrier fluid and the eutectic metal alloy to a specified downhole temperature within the subterranean formation and causing the crosslinking agent to crosslink the hydroxyethyl cellulose and the eutectic metal alloy to solidify to form a seal comprising the eutectic metal alloy distributed across a crosslinked polymer matrix;

preventing, by the seal, fluid from flowing from the wellbore and into the subterranean formation; and

drilling through the packer to remove the packer from the wellbore.