Self-circulating drill bit

• US 8,833,490 B2
• Filed: 11/06/2008
• Issued: 09/16/2014
• Est. Priority Date: 11/22/2007
• Status: Expired due to Fees

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Johnson, Ashley
• Primary Examiner(s): Bomar, Shane
• Assistant Examiner(s): WALLACE, KIPP CHARLES
• Application Number:
  US12/743,599
• Publication Number:
  US 20100319995A1
• Time in Patent Office: 2,140 Days
• Field of Search: 175 79- 83
• US Class Current: 175/57
• CPC Class Codes: E21B 10/60 characterised by conduits or nozzles for drilling fluids for roller bits E21B10/18; for percussion drill bits E21B10/38
• CPC Class Codes: E21B 21/12 using drilling pipes with plural fluid passages, e.g. closed circulation systems
• CPC Class Codes: E21B 4/006 Mechanical motion converting means, e.g. reduction gearings E21B4/10 takes precedence

Abstract

A drilling system comprising a drive shaft having a fluid flow conduit extending therethrough; a drill bit mounted for rotation by the drive shaft and having a bit face which, in use, contacts a formation to be drilled, and including a fluid flow passage with an outlet near the center of the bit face; a first fluid flow line extending from the outside of the drive shaft to the flow passage in the drill bit; and a second fluid flow line extending from the outside of the drive shaft to the flow conduit. A method of drilling a well using such a system comprise positioning the system in a borehole; rotating the drive shaft to rotate the bit; urging the bit against the formation to be drilled; and pumping drilling fluid down the borehole so as to pass though the first flow line and to exit the fluid flow passage in the drill bit via the outlet, flow over the bit face and pass into the fluid low conduit via the second fluid flow line.

Claims

1. A drilling system comprising:

a drive shaft having a fluid flow conduit extending therethrough;

a drill bit mounted for rotation by the drive shaft and having a bit face which, in use, contacts a formation to be drilled, and having a fluid flow passage with an outlet near the center of the bit face;

a baffle projecting from an outer periphery of the drive shaft, wherein an outer diameter of the baffle is less than an outer diameter of the drill bit;

a first fluid flow line extending from the outside of the drive shaft to the flow passage in the drill bit, wherein the first fluid flow line is configured to direct fluid flowing down an annulus into the fluid flow passage of the drill bit; and

a second fluid flow line extending from the outside of the drive shaft to the fluid flow conduit, wherein the second fluid flow line is configured to return fluid around the drill bit to the fluid flow conduit of the drive shaft,

wherein the first fluid line has an inlet which is on an opposite side of the baffle to the drill bit, and the second fluid line has an inlet between the baffle and the drill bit.

2. The system as claimed in claim 1, wherein, the drive shaft is mounted for rotation in a bottom-hole assembly (“

BHA”

).

3. The system as claimed in claim 2, wherein the first and second fluid flow lines extend through the BHA to the bit and drive shaft respectively.

4. The system as claimed in claim 3, wherein the first and second fluid flow lines comprise first parts formed in the BHA and second parts formed in the bit or drive shaft respectively.

5. The system as claimed in claim 4, wherein the second part of the second flow line comprises one or more holes extending from the fluid flow conduit.

6. The system as claimed in claim 5, wherein the holes are be angled to the radial direction.

7. A method of drilling a well, comprising the steps of:

positioning a drilling system in a borehole, the drilling system comprising;

a drive shaft having a fluid flow conduit extending therethrough;

a drill bit mounted for rotation by the drive shaft and having a bit face which, in use, contacts a formation to be drilled, and having a fluid flow passage with an outlet near the center of the bit face;

a baffle projecting from an outer periphery of the drive shaft, wherein an outer diameter of the baffle is less than an outer diameter of the drill bit;

a first fluid flow line extending from the outside of the drive shaft to the fluid flow passage in the drill bit; and

a second fluid flow line extending from the outside of the drive shaft to the fluid flow conduit, wherein the first fluid flow line has an inlet which is on an opposite side of the baffle to the drill bit, and the second fluid flow line has an inlet between the baffle and the drill bit;

rotating the drive shaft to rotate the bit;

urging the bit against the formation to be drilled; and

pumping drilling fluid down the borehole so as to pass through the first flow line and to exit the fluid flow passage in the drill bit via the outlet, and flow over the bit face and pass into the fluid flow conduit via the second fluid flow line.