WELLBORE DRILL BIT HAVING SHEAR CUTTERS AND GOUGING CUTTERS
A fixed cutter drill bit includes a bit body and at least one primary blade formed in the bit body and defining a surface profile on the bit body. The at least one primary blade extends from a first selected radial distance from a center or rotation of the bit body to a gage portion. At least one shear cutter affixed to the at least one blade. At least one gouging cutter affixed to the bit body rotationally ahead of the at least one blade. At least one nozzle is disposed in the bit body in a rotational position between the at least one primary blade and the at least one gouging cutter.
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STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot applicable.
THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENTNot Applicable
BACKGROUNDThis disclosure relates generally to the field of wellbore drill bits used for drilling subsurface earthen formations. More particularly, the disclosure relates to fixed cutter wellbore drill bits having shear type cutting elements (“cutters”) and pick or gouging type cutters.
Fixed cutter bits known in the art include polycrystalline diamond compact (“PDC”) bits, wherein a plurality of PDC cutters are affixed to a bit body in a selected arrangement on one or more blades formed in the bit body.
Gouging type cutters are used in drill bits for drilling mine shafts or tunnels, among other uses. Such bits are known in the art as “claw” bits, one example of which is sold under the trademark QUI-KLAW, which is a trademark of Drillhead, Inc. Such bits are known to be useful in drilling clay, unconsolidated sand, loose rock and gravel.
U.S. Pat. No. 8,505,634 issued to Lyons et al. describes a drill bit having gouging cutters disposed adjacent to shear cutters on a blade on the bit body. The shear cutters have a planar cutting face, while the gouging cutting elements have a non-planar cutting face, e.g., dome shaped or cone shaped.
Another type of fixed cutter drill bit that has both shear cutters and gouging cutters is sold under the trademark PEXUS, which is a trademark of Shear, Bits, Ltd., 407 2nd St. S.W., Suite 300, Calgary AB T2P 2Y3, Canada. It has been observed that such drill bits may exhibit premature wear on the shear cutters disposed on radially outward (from the center of rotation of the bit) portions of blades (the “profile”). Such wear is believed to be a result of being shielded from high velocity drilling fluid flow by the gouging elements, such that such shear cutter overheat and wear more quickly than expected. In applications where a drill bit designer would select low cost shear cutters on conventional PDC bits, such gouging and shear cutter bits need cutters made from more heat resistant and therefore more expensive cutters to avoid premature cutter wear due to thermal degradation (i.e., overheating of the cutters).
It has also been observed that the foregoing drill bits using shear and gouging type cutters may generally drill through subsurface formations at slower rates lower than conventions fixed cutter (e.g., PDC) drill bits. It is believed that such slower drilling rates are related to the hydraulic energy of the drilling fluid pumped through the drill bit courses or nozzles in the bit body being directed less at the PDC cutters than at the gouging elements. Such slower drilling rates may also be due to addition of gouging elements to a full shear cutter drill bit cutting structure may add excessive cutter surface area in contact with the earthen formations.
An example embodiment of a wellbore drill bit according to the present disclosure is shown in top view (viewed from the cutting end) in
The present example embodiment may include one or more circumferentially, primary blade(s) 14. The one or more primary blade(s) 14 may extend radially from a first selected radial distance (D in
The present example embodiment may include one or more secondary blades 15. The one or more secondary blades 15 may extend from a second, respective radial distance (D2 in
Any or all of the one or more shear cutters 20 may be affixed to a pocket or similar mounting feature formed into the one or more primary blades 14 (and the secondary blade(s) 15 if shear cutters are used thereon) using any attachment method or device known in the art. Such methods or devices may include, but are not limited to brazing.
In the present example embodiment, at least one or a plurality of gouging cutters 16 may be affixed to the bit body 12 rotationally, circumferentially or azimuthally displaced from the primary blade(s) 14 by a selected azimuthal angle along a direction of rotation 11 of the bit body 12, the direction of rotation 11 being that which bit is rotated in a wellbore to drill through subsurface formations. In the present example embodiment, the one or more gouging cutters 16 may be rotationally ahead of a corresponding primary blade 12, that is, rotationally displaced in the direction of rotation to be rotationally forward of a cutting surface (20A in
The terms “azimuthally” and “circumferentially” and “rotationally” may mean angularly displaced referenced to the direction of rotation 11. “Rotationally ahead of” may mean angularly advanced along the direction of rotation 11. “Rotationally behind” may mean angularly in back of with reference to the direction of rotation 11. In order to avoid ambiguity, with reference to the shear cutters 20, “ahead of” the shear cutters 20 rotationally, azimuthally or circumferentially means ahead in the direction of rotation 11 with respect to a cutting surface of the shear cutters.
In the present example embodiment, the gouging cutters 16 may be affixed to the bit body 12 in any suitable geometric arrangement for gouging cutters used in a fixed cutter drill bit having at least one shear cutter. For purposes of describing a drill bit according to the present disclosure, a first group 16A of shear cutters may be disposed rotationally displaced from, e.g., rotationally ahead of one of the primary blades 14, this particular primary blade being shown at 24 in
The example embodiment shown in
A side view of the example embodiment shown in
In some embodiments, the one or more primary blade(s) 14 and the one or more secondary blades 15 may be shaped to include a tapered face 14C below (in the viewing direction of
In embodiments that have one or more shear cutters 20 on the one or more secondary blades 15, such shear cutters 20 may define a profile surface that is, at corresponding radial distances from the center or rotation C, located a selected distance H lower (in the plane of view of
A side view of the example embodiment shown in
In example embodiments such as shown in
A drill bit according to the present disclosure having one or more gouging cutters on a drill bit having shear cutters may include one or more of the following:
(i) protects the shear cutters from impact damage;
(ii) create large fractures in the formations which are more efficient for drilling than shearing in some types of formations;
(iii) drills formations with a smoother torque response than a comparable drill bit having shear cutters alone; and
(iv) enables the bit drill to successfully drill through formations that conventional fixed cutter (shear cutter only) drill bits cannot drill.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims
1. A fixed cutter drill bit, comprising:
- a bit body;
- at least one primary blade formed in the bit body and defining a surface profile on the bit body, the at least one primary blade extending from a first selected radial distance from a center or rotation of the bit body to a gage portion;
- at least one shear cutter affixed to the at least one blade;
- at least one gouging cutter affixed to the bit body rotationally displaced from the at least one blade; and
- at least one fluid orifice disposed in the bit body in a rotational position between the at least one primary blade and the at least one gouging cutter.
2. The fixed cutter drill bit of claim 1 further comprising at least one secondary blade formed in the bit body and circumferentially spaced apart from, the at least one secondary blade extending from a second selected distance from the center or rotation and extending radially to a gage portion, the second distance greater than the first distance.
3. The fixed cutter drill bit of claim 2 further comprising at least one shear cutter on the at least one secondary blade.
4. The fixed cutter drill bit of claim 2 wherein the at least one secondary blade defines a surface profile located at a selected distance less extensive along a longitudinal dimension of the bit body than a corresponding surface profile defined by the at least one gouging cutter.
5. The fixed cutter drill bit of claim 2 wherein the at least one secondary blade comprises at least one shear cutter thereon, the at least one shear cutter on the at least one secondary blade defining a surface profile located at a selected distance lower along a longitudinal dimension of the bit body than a corresponding surface profile defined by the at least one gouging cutter.
6. The fixed cutter drill bit of claim 1 wherein the at least one shear cutter on the at least one primary blade defines a surface profile located at a selected distance lower along a longitudinal dimension of the bit body than a corresponding surface profile defined by the at least one gouging cutter.
7. The fixed cutter drill bit of claim 1 wherein the at least one shear cutter comprises a polycrystalline diamond compact cutter.
8. The fixed cutter drill bit of claim 1 wherein the at least one gouging cutter comprises a tungsten carbide insert.
9. The fixed cutter drill bit of claim 1 wherein the at least one shear cutter is disposed at a radial distance from a center of rotation of the bit body less than a gage diameter defined by the bit body.
Type: Application
Filed: Apr 21, 2015
Publication Date: Oct 27, 2016
Inventors: Ryan J. C. Marley (Airdrie), John James Herman (Cypress County), Timothy P. Beaton (Calgary)
Application Number: 14/691,604