Axial-field multi-armature alternator system for downhole drilling
A downhole drilling system is disclosed. The downhole drilling system may include an axial-field multi-armature alternator system, mechanically driven by a turbine; a pulse-generating circuit electrically coupled to the axial-field multi-armature alternator system, the pulse-generating circuit receiving power from the axial-field multi-armature alternator system to provide an electric pulse; and a drill bit including a first electrode and a second electrode electrically coupled to the pulse-generating circuit to receive the electric pulse from the pulse-generating circuit.
1. A downhole drilling system, comprising:
an axial-field multi-armature alternator system;
a pulse-generating circuit electrically coupled to the axial-field multi-armature alternator system, the pulse-generating circuit receiving power from the axial-field multi-armature alternator system to provide an electric pulse; and
a drill bit including a first electrode and a second electrode electrically coupled to the pulse-generating circuit to receive the electric pulse from the pulse-generating circuit.
2. The downhole drilling system of claim 1 , wherein the axial-field multi-armature alternator system includes:
a core shaft;
a plurality of armatures physically coupled to the core shaft, each armature spaced-apart from a neighboring armature a distance and electrically coupled to each neighboring armature;
a first outer body coupled to a first plurality of magnetic assemblies, the first outer body surrounding the first plurality of magnetic assemblies; and
a second outer body coupled to a second plurality of magnetic assemblies, the second outer body surrounding the second plurality of magnetic assemblies,
wherein, for each armature, a first set of corresponding magnetic assemblies of the first plurality of magnetic assemblies and a second set of corresponding magnetic assemblies of the second plurality of magnetic assemblies surrounds the armature.
3. The downhole drilling system of claim 2 , wherein each set of corresponding magnetic assemblies has a washer-type geometric shape.
4. The downhole drilling system of claim 2 , wherein each magnetic assembly of each set of corresponding magnetic assemblies has a half-washer-type geometric shape.
5. The downhole drilling system of claim 1 , wherein the axial-field multi-armature alternator system provides greater than 1 kW of power to the pulse-generating circuit.
6. The downhole drilling system of claim 1 , wherein the axial-field multi-armature alternator system provides greater than 500 kW of power to the pulse-generating circuit.
7. The downhole drilling system of claim 1 , wherein the pulse-generating circuit is physically positioned between the axial-field multi-armature alternator system and the drill bit.
8. The downhole drilling system of claim 1 , further comprising a turbine mechanically coupled to the axial-field multi-armature alternator system.
9. The downhole drilling system of claim 1 , wherein the electric pulse from the pulse-generating circuit applies a voltage of approximately 150 kV across the first electrode and the second electrode.
10. The downhole drilling system of claim 1 , wherein the drill bit is one of an electrocrushing drill bit or an electrohydraulic drill bit.
11. An axial-field multi-armature alternator system for providing power in a downhole drilling system, the system comprising:
a core shaft;
a plurality of armatures physically coupled to the core shaft, each armature spaced-apart from a neighboring armature a distance and electrically coupled to each neighboring armature;
a first outer body coupled to a first plurality of magnetic assemblies, the first outer body surrounding the first plurality of magnetic assemblies; and
a second outer body coupled to a second plurality of magnetic assemblies, the second outer body surrounding the second plurality of magnetic assemblies,
wherein, for each armature, a first set of corresponding magnetic assemblies of the first plurality of magnetic assemblies and a second set of corresponding magnetic assemblies of the second plurality of magnetic assemblies surrounds the armature.
12. The axial-field multi-armature alternator system of claim 11 , wherein the core shaft passes through each of the armatures.
13. The axial-field multi-armature alternator system of claim 12 , wherein each set of corresponding magnetic assemblies has a washer-type geometric shape.
14. The axial-field multi-armature alternator system of claim 13 , wherein each magnetic assembly of each set of corresponding magnetic assemblies has a half-washer-type geometric shape.
15. The axial-field multi-armature alternator system of claim 11 , wherein the first and the second outer body surround the plurality of armatures.
16. The axial-field multi-armature alternator system of claim 11 , wherein the first outer body and the second outer body are rotatable around the core shaft.
17. The axial-field multi-armature alternator system of claim 11 , further comprising a first and a second hub surrounding each armature.
18. The axial-field multi-armature alternator system of claim 11 , further comprising a bearing coupled to the core shaft.
19. The axial-field multi-armature alternator system of claim 11 , wherein the axial-field multi-armature alternator system is integrated within a bottom-hole assembly.
20. A method, comprising:
placing a drill bit downhole in a wellbore;
providing electrical power from an axial-field multi-armature alternator system to a pulse-generating circuit electrically coupled to the drill bit, the axial-field armature alternator system located downhole in the wellbore and including:
a core shaft,
a plurality of armatures physically coupled to the core shaft, each armature spaced-apart from a neighboring armature a distance and electrically coupled to each neighboring armature,
a first outer body coupled to a first plurality of magnetic assemblies, the first outer body surrounding the first plurality of magnetic assemblies, and
a second outer body coupled to a second plurality of magnetic assemblies, the second outer body surrounding the second plurality of magnetic assemblies,
wherein, for each armature, a first set of corresponding magnetic assemblies of the first plurality of magnetic assemblies and a second set of corresponding magnetic assemblies of the second plurality of magnetic assemblies surrounds the armature;
generating an electric pulse with the pulse-generating circuit;
forming an electrical arc between a first electrode and a second electrode of the drill bit;
fracturing a rock formation at an end of the wellbore with the electrical arc; and
removing fractured rock from the end of the wellbore.