Power cartridges for setting tools

1. A tool string disposable in a wellbore, comprising:

a plug configured to seal against an inner surface of a tubular string disposed in the wellbore; and

a setting tool coupled to the plug, comprising:

a piston slidably disposed in a housing of the setting tool and comprising a central passage; and

a combustible assembly disposed in the passage of the piston, wherein the combustible assembly comprises a housing and combustible material disposed in the housing, and wherein both the housing of the combustible assembly and the combustible material are disposed in the passage of the piston;

wherein the housing of the combustible assembly contacts an inner surface of the piston whereby an arcuate gap is formed between the housing of the combustible assembly and the inner surface of the piston;

wherein, in response to a pressurization of the central passage of the piston of the setting tool, the setting tool is configured to actuate the plug to seal against the inner surface of the tubular string.

2. The tool string of claim 1 , wherein the combustible assembly housing comprises a plurality of the planar surfaces and wherein the planar surfaces are circumferentially spaced about the housing.

3. The tool string of claim 1 , wherein:

the housing of the setting tool is coupled to a housing of the plug; and

the setting comprises a mandrel coupled to the piston, the mandrel of the setting tool being coupled to a mandrel of the plug, and wherein displacement of the mandrel of the setting tool results in displacement of the mandrel of the plug.

4. The tool string of claim 1 , further comprising:

a plug-shoot firing head coupled to the setting tool; and

a wireline extending from the tool string to an upper end of the wellbore;

wherein the plug-shoot firing head comprises an ignitor ballistically coupled to the combustible assembly and is configured to ignite the combustible material of the combustible assembly in response to receiving a signal transmitted by the wireline.

5. The tool string of claim 1 , wherein the combustible assembly comprises a power cartridge.

6. The tool string of claim 1 , wherein the combustible assembly housing comprises a rectangular cross-section having a maximum width and a minimum width that is less than the maximum width.

7. The tool string of claim 1 , wherein the combustible assembly housing comprises a hexagonal cross-section having a maximum width and a minimum width that is less than the maximum width.

8. The tool string of claim 1 , wherein the setting tool comprises:

a first chamber and a second chamber are formed in the setting tool housing;

wherein fluid communication between the first chamber and the second chamber is restricted when the piston is in a first position, and wherein fluid communication is permitted between the first chamber and the second chamber when the piston is in a second position.

9. The tool string of claim 8 , wherein the setting tool comprises:

a mandrel slidably disposed in the setting tool housing and coupled to the piston; and

an annular seal positioned between the mandrel and the setting tool housing, wherein the annular seal isolates the first chamber from the second chamber in the setting tool housing.

10. The tool string of claim 8 , wherein the arcuate gap comprises a flowpath for providing fluid communication between a chamber formed in the combustible assembly housing and the first chamber.

11. The tool string of claim 10 , wherein the arcuate gap is formed between a planar surface of the combustible assembly housing and the inner surface of the setting tool housing.

12. A setting tool for actuating a plug in a wellbore, comprising:

a housing comprising a central passage, wherein a first chamber and a second chamber are formed in the setting tool housing;

a piston slidably disposed in the setting tool housing and comprising a central passage; and

a combustible assembly disposed in the passage of the piston, wherein the combustible assembly comprises a housing and combustible material disposed in the combustible assembly housing;

wherein fluid communication between the first chamber and the second chamber is restricted when the piston is in a first position, and wherein fluid communication is permitted between the first chamber and the second chamber when the piston is in a second position;

wherein, in response to a pressurization of the central passage of the piston, the setting tool is configured to displace the piston between the first position and the second position;

wherein an opening is formed between an outer surface of the combustible assembly housing and an inner surface of the piston, and wherein the opening comprises a flowpath for providing fluid communication between a chamber formed in the combustible assembly housing and the first chamber.

13. The setting tool of claim 12 , further comprising:

a mandrel slidably disposed in the setting tool housing and coupled to the piston; and

an annular seal positioned between the mandrel and the setting tool housing, wherein the annular seal isolates the first chamber from the second chamber in the setting tool housing.

14. The setting tool of claim 12 , wherein the opening comprises an arcuate opening formed between a planar surface of the combustible assembly housing and the inner surface of the setting tool housing.

15. The setting tool of claim 12 , wherein an outer surface of the combustible assembly housing comprises a plurality of circumferentially spaced planar surfaces.

16. The setting tool of claim 12 , wherein the combustible assembly housing comprises a rectangular cross-section having a maximum width and a minimum width that is less than the maximum width.

17. The setting tool of claim 12 , wherein the combustible assembly housing comprises a hexagonal cross-section having a maximum width and a minimum width that is less than the maximum width.

18. The setting tool of claim 12 , wherein the combustible assembly comprises a power cartridge.