Two-part bit wiring assembly
A downhole drilling assembly may comprise a sub secured between a drill string and a drill bit. The sub may comprise a cavity with a chassis housed therein. The drill bit may also comprise a cavity with an extender housed therein. This extender may provide access for various types of communication to reach into the drill bit's cavity. Several pairs of interfacing exchange surfaces may allow for communication (e.g. passing electrical, hydraulic, optical or electromagnetic signals) between these various elements. One pair of interfacing exchange surfaces, between the drill string and the chassis, may allow for communication regardless of relative rotational orientation. Two other pairs of interfacing exchange surfaces, one between the chassis and the extender and another between the extender and the drill bit, may require a specific rotational orientation for communication.
1. A downhole drilling assembly, comprising:
a drill string secured to a sub;
a chassis housed within a cavity of the sub;
the sub secured to a drill bit;
an extender housed within a cavity of the drill bit;
a first pair of interfacing exchange surfaces, between the chassis and the drill string, are fixed together independent of rotational orientation;
a second pair of interfacing exchange surfaces, between the chassis and the extender, are fixed together in a specific rotational orientation; and
a third pair of interfacing exchange surfaces, between the extender and the drill bit, are fixed together in a specific rotational orientation.
2. The downhole drilling assembly of claim 1 , wherein the first, second and third pairs of interfacing exchange surfaces are each capable of exchanging at least one of electrical, hydraulic, optical and electromagnetic signals.
3. The downhole drilling assembly of claim 1 , wherein:
the drill string comprises a first protrusion inserted into the cavity of the sub;
one of the first pair of interfacing exchange surfaces is disposed on an end of the first protrusion;
the sub comprises a second protrusion inserted into the cavity of the drill bit; and
none of the interfacing exchange surfaces are disposed on the second protrusion.
4. The downhole drilling assembly of claim 1 , wherein the drill string retains the chassis within the cavity of the sub and the sub retains the extender within the cavity of the drill bit.
5. The downhole drilling assembly of claim 1 , wherein the drill string is secured to the sub via threads that cease rotation at a fixed position and the sub is secured to the drill bit via threads that cease rotation at a fixed position.
6. The downhole drilling assembly of claim 5 , wherein the sub is additionally secured to the drill bit via a weld or adhesive.
7. The downhole drilling assembly of claim 5 , wherein the sub is additionally secured to the drill bit via a mechanical fastener requiring a specialized tool for removal.
8. The downhole drilling assembly of claim 1 , wherein the sub and chassis are interchangeable with an alternate sub and chassis of different axial length.
9. The downhole drilling assembly of claim 1 , wherein the extender is interchangeable with an alternate extender.
10. The downhole drilling assembly of claim 1 , wherein the extender comprises a proximal end contacting a nadir of the drill bit cavity and a distal end positioned within 2 inches of a mouth of the drill bit cavity.
11. The downhole drilling assembly of claim 1 , wherein the extender comprises a generally conical exterior shape.
12. The downhole drilling assembly of claim 1 , wherein an exterior shape of the extender narrows as it nears a mouth of the drill bit cavity.
13. The downhole drilling assembly of claim 1 , wherein one of each of the first and second pairs of interfacing exchange surfaces are connected via conduits passing through the chassis.
14. The downhole drilling assembly of claim 1 , wherein one of each of the second and third pairs of interfacing exchange surfaces are connected via conduits passing through the extender.
15. The downhole drilling assembly of claim 1 , further comprising a fluid channel passing through the drill string, chassis, and extender.
16. The downhole drilling assembly of claim 1 , wherein the sub is axially longer than the drill bit.
17. The downhole drilling assembly of claim 1 , wherein the chassis comprises electronics disposed circumferentially about an exterior surface thereof, within a pressure chamber between the chassis and the sub, and connected to at least one of the first and second pairs of interfacing exchange surfaces.
18. The downhole drilling assembly of claim 1 , wherein both the second and third pairs of interfacing exchange surfaces comprise stab connectors.
19. The downhole drilling assembly of claim 1 , wherein the drill bit comprises cutting elements exposed thereon axially spanning the third pair of interfacing exchange surfaces.
20. The downhole drilling assembly of claim 1 , wherein the cavity of the drill bit comprises threads therein and the third pair of interfacing exchange surfaces is positioned inside the threads.