Force-activated thermal battery for use in a wellbore

1. A device comprising:

a body coupleable to a thermal battery and positionable in a wellbore, the body comprising a piston retained at a first position in an inner area of the body, the piston being moveable from the first position to a second position in response to a force applied to the body and for activating the thermal battery by moving to the second position, wherein the thermal battery is a first thermal battery, and wherein the body is removable from the wellbore separate from the first thermal battery and reusable with a second thermal battery.

2. The device of claim 1 , wherein the body further comprises shear pins for retaining the piston at the first position and for shearing in response to the force exceeding a threshold value to allow the piston to move to the second position.

3. The device of claim 2 , wherein the body further comprises a firing pin coupled to a surface of the piston for contacting a primer as the piston moves to the second position to ignite pyrotechnics that activate the thermal battery in response to contact with the firing pin.

4. The device of claim 3 , wherein the body further comprises a primer having a piezoelectric material for responding to contact with the firing pin by generating an electrical signal to ignite the pyrotechnics.

5. The device of claim 2 , wherein the body further comprises a magnet coupled to a surface of the piston for generating an electrical signal by passing through a coil as the piston moves to the second position, the electrical signal being transmittable for igniting pyrotechnics to activate the thermal battery.

6. The device of claim 1 , wherein the force is a change in a pressure in the wellbore caused by a pump at a surface of the wellbore.

7. The device of claim 1 , wherein the body is coupleable to a tubular string and the force is caused at least in part by a drop bar moving through the tubular string.

8. The device of claim 1 , wherein the body further comprises an electrical power-conditioning module communicatively coupleable between the first thermal battery and a tool powered by electrical power from the first thermal battery for regulating an output of the first thermal battery.

9. A system comprising:

a tool positionable in a wellbore;

a thermal battery positionable in the wellbore and communicatively coupleable to the tool for providing power to the tool in response to being heated above a threshold temperature; and

a body positionable in the wellbore and coupleable to the thermal battery for responding to a force by heating the thermal battery above the threshold temperature, and wherein the thermal battery is a first thermal battery, and wherein the body is removable from the wellbore separate from the first thermal battery and reusable with a second thermal battery.

10. The system of claim 9 , wherein the body comprises a piston retained at a first position in an inner area of the body by shear pins, the shear pins for shearing in response to the force exceeding a threshold value to allow the piston to move to a second position.

11. The system of claim 10 , wherein the body further comprises a firing pin coupled to a surface of the piston for contacting a primer in response to the piston moving to the second position to ignite pyrotechnics for heating the thermal battery to a temperature above the threshold temperature.

12. The system of claim 10 , wherein the body further comprises a magnet coupled to a surface of the piston for generating an electrical signal by passing through a coil in response to the piston moving to the second position, the electrical signal being transmittable for igniting pyrotechnics to heat the thermal battery to a temperature above the threshold temperature.

13. The system of claim 10 , further comprising a pump positionable at a surface of the wellbore for generating the force by changing a pressure in the wellbore.

14. The system of claim 10 , further comprising a tubular string coupleable to the body, wherein the force is at least partially generatable by a drop bar traversing the tubular string.

15. The system of claim 9 , further comprising an electrical power-conditioning module communicatively coupleable between the thermal battery and the tool for regulating an output of the thermal battery.

16. A method comprising:

moving a piston retained in a body positioned in a wellbore from a first position in an inner area of the body to a second position in the inner area of the body in response to a force being applied to the piston;

generating an electrical signal by moving a magnet coupled to the piston through a coil coupled to the body as a result of the piston moving to the second position;

igniting pyrotechnics coupled to a thermal battery using the electrical signal;

heating a thermal battery positioned in the wellbore with the pyrotechnics based on the piston moving to the second position; and

activating the thermal battery coupled to the body based on heating the thermal battery above a threshold temperature.

17. The method of claim 16 , wherein moving the piston comprises:

shearing a shear pin retaining the piston at the first position in response to the force exceeding a threshold value.

18. The method of claim 16 , wherein the thermal battery is a first thermal battery and the force is a first force, the method further comprising:

generating the first force by using a pump positioned at a surface of the wellbore to change a pressure in the wellbore;

powering a first tool in the wellbore with the first thermal battery;

removing the body from the wellbore separate from the first thermal battery; and

positioning the body in the wellbore to activate a second thermal battery in response to a second force being applied to the piston.