In situ heat generation

1. A method for generating in situ heat downhole comprising:

introducing a fluid composition into a wellbore, wherein the fluid composition comprises:

a metallic powder comprising a plurality of metallic powder particles, each metallic powder particle comprising:

at least one metallic particle core having a melting temperature (TP); wherein the metallic particle core comprises a metal selected from the group consisting of magnesium, aluminum, zinc, iron, manganese, alloys thereof, and combinations thereof;

a coating disposed on the metallic particle core, wherein the coating comprises a material having a melting temperature (TC);

wherein at least two metallic powder particles are configured for solid-state sintering to one another at a predetermined sintering temperature (TS), and TS is less than TP and TC and wherein the metallic powder particles are sintered together to form a metallic particle compact, wherein the size of the metallic particle compact ranges from about 500 μm to about 20 cm; and

a base fluid selected from the group consisting of a drilling fluid, a completion fluid, a stimulation fluid, a workover fluid, activation fluid, and mixtures thereof;

releasing at least one metallic particle core from the plurality of metallic powder particles; and

reacting the at least one released metallic particle core with a heat-generating fluid and thereby generating heat.

2. The method of claim 1 , wherein the amount of the metallic powder particles in the fluid composition ranges from about 0.5 wt % to about 30 wt %.

3. The method of claim 1 , wherein at least one dimension of each metallic powder particle ranges from about 50 nm to about 5000 μm.

4. The method of claim 1 , wherein the releasing the at least one metallic particle core may occur by a method selected from the group consisting of dissolving the at least one coating, disintegrating the at least one coating, corroding the at least one coating, melting the at least one coating, and combinations thereof.

5. The method of claim 1 , wherein the coating comprises a material selected from the group consisting of Al, Zn, Mn, Mg, Mo, W, Cu, Fe, Si, Ca, Co, Ta, Re, Ni, an oxide thereof, a carbide thereof, a nitride thereof, alloys thereof, and a combination of any of the aforementioned materials; and wherein the coating material has a chemical composition that is different from the chemical composition of the metallic particle core.

6. The method of claim 1 , wherein the coating comprises a single coating layer.

7. The method of claim 1 , wherein the coating comprises a plurality of coating layers.

8. The method of claim 7 , wherein the plurality of coating layers comprises a first coating layer disposed on the metallic particle core and at least a second coating layer disposed on the first coating layer.

9. The method of claim 8 , wherein the first coating layer comprises a material selected from the group consisting of Al, Zn, Mn, Mg, Mo, W, Cu, Fe, Si, Ca, Co, Ta, Re, Ni, an oxide thereof, a carbide thereof, a nitride thereof, an alloy thereof, and a combination of any of the aforementioned materials; wherein the at least second coating layer comprises a material selected from the group consisting of Al, Zn, Mn, Mg, Mo, W, Cu, Fe, Si, Ca, Co, Ta, Re, Ni, an oxide thereof, a carbide thereof, a nitride thereof, an alloy thereof, and a combination of any of the aforementioned materials; and wherein the first coating layer comprises a chemical composition that is different from the at least second coating layer.

10. The method of claim 1 , wherein the coating has a thickness ranging from about 25 nm to about 2500 nm.

11. The method of claim 1 , wherein at least one dimension of the metallic particle core ranges from about 25 nm to about 5000 μm.

12. The method of claim 1 , wherein the heat-generating fluid is selected from the group consisting of acids, bases, water, and mixtures thereof.

13. The method of claim 1 , further comprising performing an action with the generated heat, wherein the action is selected from the group consisting of:

melting wax;

dissolving paraffins;

dissolving asphaltenes;

increasing the near wellbore temperature prior to the pumping downhole of a hydraulic fracturing treatment;

activating the expansion of polymers to be used as a sand screen, packer, and combinations thereof;

and combinations thereof.

14. The method of claim 1 , further comprising generating more heat in situ downhole as compared to the wellbore absent the with the introduction of the fluid composition.

15. The method of claim 1 , wherein a majority of particle cores are released from the plurality of powder particles.

16. The method of claim 1 where the coating prevents the at least one metallic particle core from contacting the heat-generating fluid prior to the releasing of the at least one metallic particle core.

17. A method of generating in situ heat downhole comprising:

introducing a fluid composition into a wellbore, wherein the fluid composition comprises:

a metallic powder comprising a plurality of metallic powder particles, wherein the amount of the metallic powder particles in the fluid composition ranges from about 0.5 wt % to about 30 wt %, each metallic powder particle comprising:

at least one metallic particle core having a melting temperature (TP); wherein the metallic particle core comprises a metal selected from the group consisting of magnesium, aluminum, zinc, iron, manganese, alloys thereof, and combinations thereof;

a coating disposed on the metallic particle core; wherein the coating comprises a material selected from the group consisting of Al, Zn, Mn, Mg, Mo, W, Cu, Fe, Si, Ca, Co, Ta, Re, Ni, an oxide thereof, a carbide thereof, a nitride thereof, alloys thereof, and a combination of any of the aforementioned materials; and wherein the coating material has a melting temperature (TC); and

a base fluid selected from the group consisting of a drilling fluid, a completion fluid, a stimulation fluid, a workover fluid, an activation fluid, and mixtures thereof;

releasing at least one metallic particle core from the plurality of metallic powder particles; wherein the releasing the at least one metallic particle core may occur by a method selected from the group consisting of dissolving the at least one coating, disintegrating the at least one coating, corroding the at least one coating, and combinations thereof; and

generating heat by reacting the at least one released metallic particle core with a heat-generating fluid.

18. A method for generating in situ heat downhole comprising:

introducing a fluid composition into a wellbore, wherein the fluid composition comprises:

a metallic powder comprising a plurality of metallic powder particles, each metallic powder particle comprising:

at least one metallic particle core having a melting temperature (TP);

a coating disposed on the metallic particle core, wherein the coating comprises a material having a melting temperature (TC); and

wherein at least two metallic powder particles are configured for solid-state sintering to one another at a predetermined sintering temperature (TS), and TS is less than TP and TC;

where the coating prevents the at least one metallic particle core from contacting a heat-generating fluid prior to the releasing of the at least one metallic particle core;

a base fluid selected from the group consisting of a drilling fluid, a completion fluid, a stimulation fluid, a workover fluid, activation fluid, and mixtures thereof;

releasing at least one metallic particle core from the plurality of metallic powder particles, wherein a majority of particle cores are released from the plurality of powder particles; wherein the metallic particle core comprises a metal selected from the group consisting of magnesium, aluminum, zinc, iron, manganese, alloys thereof, and combinations thereof;

reacting the majority of released metallic particle cores with the heat-generating fluid and thereby generating heat; and

performing an action with the heat selected from the group consisting of:

melting wax;

dissolving paraffins;

dissolving asphaltenes;

increasing the near wellbore temperature prior to the pumping downhole of a hydraulic fracturing treatment;

activating the expansion of polymers to be used as a sand screen, packer, and combinations thereof; and

combinations thereof.