PDC BIT HAVING SPLIT BLADES
A drill bit for drilling a borehole in a formation, the drill bit including a bit body having a bit face including a cone region, a nose region, a shoulder region, and a gage region, at least one disjointed blade disposed on the bit face, the disjointed blade including a first section beginning proximate a central axis of the bit and extending less than full gage, and a second section beginning a selected distance from the central axis and extending to full gage, and a plurality of cutting elements mounted on the at least one disjointed blade is disclosed.
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This application, pursuant to 35 U.S.C. §119(e), claims priority to U.S. Provisional Application Ser. No. 61/083,851, filed Jul. 25, 2008. That application is incorporated by reference in its entirety.
BACKGROUND OF INVENTION1. Field of the Invention
Embodiments disclosed herein generally relate to fixed cutter drill bits. In particular, embodiments disclosed herein relate to fixed cutter drill bits having a unique blade design.
2. Background Art
Historically, there have been two types of drill bits used drilling earth formations, drag bits and roller cone bits. Roller cone bits include one or more roller cones rotatably mounted to the bit body. These roller cones have a plurality of cutting elements attached thereto that crush, gouge, and scrape rock at the bottom of a hole being drilled. Several types of roller cone drill bits are available for drilling wellbores through earth formations, including insert bits (e.g. tungsten carbide insert bit, TCI) and “milled tooth” bits. The bit bodies and roller cones of roller cone bits are conventionally made of steel. In a milled tooth bit, the cutting elements or teeth are steel and conventionally integrally formed with the cone. In an insert or TCI bit, the cutting elements or inserts are conventionally formed from tungsten carbide, and may optionally include a diamond enhanced tip thereon.
The term “drag bits” refers to those rotary drill bits with no moving elements. Drag bits, often referred to as fixed cutter drill bits, are often used to drill a variety of rock formations. Drag bits include those having cutting elements or cutters attached to the bit body, which may be a steel bit body or a matrix bit body formed from a matrix material such as tungsten carbide surrounded by an binder material. The cutters may be formed having a substrate or support stud made of carbide, for example tungsten carbide, and an ultra hard cutting surface layer or “table” made of a polycrystalline diamond material or a polycrystalline boron nitride material deposited onto or otherwise bonded to the substrate at an interface surface. Thus, fixed cutter drill bits known in the art include polycrystalline diamond compact (PDC) bits.
The typical PDC bit includes a bit body which is made from powdered tungsten carbide infiltrated with a binder alloy within a suitable mold form. The particular materials used to form PDC bit bodies are selected to provide adequate toughness, while providing resistance to abrasive and erosive wear. The cutting elements used on these bits are typically formed from a cylindrical tungsten carbide “blank” or substrate. A diamond “table” made from various forms of natural and/or synthetic diamond is affixed to the substrate. The substrate is then generally brazed or otherwise bonded to the bit body in a selected position on the surface of the body.
A plurality of PDC cutters is mounted along the exterior face of the bit body in extensions of the bit body called “blades.” Each PDC cutter has a portion which typically is brazed in a recess or pocket formed in the blade on the exterior face of the bit body. The PDC cutters are positioned along the leading edges of the bit body blades so that as the bit body is rotated, the PDC cutters engage and drill the earth formation.
A known drill bit is shown in
Referring to
Still referring to
Blade profiles 39 and bit face 20 may also be described as two regions termed “inner region” and “outer region”, where the “inner region” is the central most region of bit 10 and is analogous to cone region 24, and the “outer region” is simply the region(s) of bit 10 outside the inner region. Using this nomenclature, the outer region is analogous to the combined shoulder region 26 and gage region 28 previously described. The inner region may be defined similarly to cone region 24.
Downwardly extending flow passages 21 have nozzles or ports 22 disposed at their lowermost ends. Bit 10 may include multiple flow passages 21 and nozzles 22. The flow passages 21 are in fluid communication with central bore 17. Together, passages 21 and nozzles 22 serve to distribute drilling fluid around the cutter elements 40 for flushing drilled formation from the bottom of the borehole away from the cutting faces 44 (
Referring to
Further, as shown in
Referring now to
Accordingly, there exists a need for means for providing greater flexibility in addressing various aspects of bit performance, including bit balance, bit hydraulics, and ROP, and greater flexibility in varying diamond density and/or cutter density across a bit face.
SUMMARY OF INVENTIONIn one aspect, embodiments disclosed herein relate to a drill bit for drilling a borehole in a formation, the drill bit including a bit body having a bit face including a cone region, a nose region, a shoulder region, and a gage region, at least one disjointed blade disposed on the bit face, the disjointed blade including a first section beginning proximate a central axis of the bit and extending less than full gage, and a second section beginning a selected distance from the central axis and extending to full gage, and a plurality of cutting elements mounted on the at least one disjointed blade.
In another aspect, embodiments disclosed herein relate to a drill bit for drilling a borehole in a formation, the drill bit including a bit body having a bit face including a cone region, a nose region, a shoulder region, and a gage region, at least one disjointed primary blade disposed on the bit face, the disjointed blade including a first section disposed primarily in the cone region, and a second section disposed primarily in at least one of the nose, shoulder, and gage regions, and at least one cutting element disposed on the first section and at least one cutting element disposed on the second section.
In another aspect, embodiments disclosed herein relate to a drill bit for drilling a borehole in a formation, the drill bit including a bit body having a bit face including a cone region, a shoulder region, and a gage region, at least one blade disposed on the bit face, the blade beginning a selected distance from the central axis and extending to full gage, at least one cutting structure disposed on the bit face in the cone region, and at least one cutting element disposed on the at least one blade.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
In one aspect, embodiments disclosed herein relate to a drill bit for drilling a borehole in a formation. More specifically, embodiments disclosed herein relate to fixed cutter drill bits, particularly, PDC drill bits.
Embodiments of the present disclosure provide a drill bit for drilling a borehole in a formation. In particular, drill bits formed in accordance with embodiments disclosed herein provide fixed cutter drill bit with a unique blade configuration that may provide enhanced bit balance and improved bit hydraulics, as well as increased ROP. Additionally, drill bits formed in accordance with embodiments disclosed herein greater flexibility in varying diamond density and/or cutter density across a bit face.
Generally speaking, a fixed cutter bit includes a bit body having a central axis 661 and a bit face 665 that may be divided into four regions. Namely, the bit face includes a cone region 656, a nose region 657, a shoulder region 658, and a gage region 659, as shown in
Referring to
As shown in
Disjointed blades 770 may be uniformly spaced around the bit face 771 or may be variably spaced about the bit face 771. Further, although three disjointed primary blades 770 are shown in
In an embodiment where two or more primary blades are disjointed blades, the relationship between the first section and second section of the first disjointed blade may differ from the relationship between the first section and second section of the second disjointed blade. For example, the first disjointed blade may include a first section and a second section, wherein the second section is radially spaced a selected distance away from the first section and is disposed at a different angle on the bit face with respect to the direction of rotation of the bit. In contrast, the second disjointed blade may include a first section and a second section, wherein the second section is disposed at the same angle as the first section, but is disposed on a different radial plane than the first section, i.e., behind the first section with respect to the direction of rotation of the bit.
In accordance with embodiments disclosed herein, each blade on the fixed cutter may be independently designed. Thus, a fixed cutter bit may include a combination of one or more of solid primary blades (i.e., conventional blades), disjointed primary blades, and secondary blades. Further, each disjointed blade may be independently designed based on the disjointed angle between the two sections of the disjointed blade, the radial plane(s) on which each section is disposed, and the number of sections included in each disjointed blade.
Secondary blades 776 may be disposed between two disjointed blades 770. In some embodiments two or more secondary blades 776 may be disposed between two disjointed blades 770. Further, secondary blades 776 may be disposed between a disjointed blade 770 and a solid (conventional) primary blade (not shown). As shown, secondary blades 770 do not extend from a location proximate central axis A. Rather, each secondary blade 776 extends from a distance D away from central axis A to the periphery of the bit, or full gage (669 in
The design of the disjointed blades 770, including, for example, number of disjointed blades, number of sections, angle between the sections, gap size between the sections, and radial planes of the sections, may be selected so as to provide improved bit hydraulic efficiency. For example, the design of the disjointed blades 770 facilitates the placement of nozzles 778 in desired areas of the bit face 771. Because the primary blades of the bit may include disjointed blades, wherein first and second sections may be disposed separate from one another, greater flexibility in the placement of nozzles is provided.
Referring now to
As depicted, each section of the disjointed blades 880a, 880b, 880c includes at least one cutting element 883 mounted thereon. The cutting elements 883 may be formed having a substrate or support stud made of carbide, for example, tungsten carbide, and an ultra hard cutting surface layer or table made of a polycrystalline diamond material or a polycrystalline boron nitride material deposited onto or otherwise bonded to the substrate at an interface surface. One of ordinary skill in the art will appreciate that any cutting element known in the art for use on a fixed cutter drill bit may be used without departing from the scope of embodiments disclosed herein. Additionally, although depicted as a single row of cutters on each section of the disjointed blade 880, multiple rows of cutters may be disposed on a single section of a single disjointed blade 880.
Referring still to
As discussed above, a disjointed blade in accordance with embodiments disclosed herein may include two or more section disposed on the bit face. In one embodiment, a first section of the disjointed blade may extend from the proximal boundary of the cone region to the distal boundary of the cone region and a second section may extend from the proximal boundary of the nose region to the distal boundary of gage region, i.e., full gage. In an embodiment where a disjointed blade includes four sections, the first section may extend from the cone proximal boundary to the cone distal boundary, the second section may extend from the nose proximal boundary to the nose distal boundary, the third section may extend from the shoulder proximal boundary to the shoulder distal boundary, and the fourth section may extend from the gage proximal boundary to the shoulder distal boundary. As will be discussed below with reference to the figures, each section may be disposed at varying angles and/or place along the same or different radial planes.
In other embodiments, a blade section of disjointed blade may overlap another section of the disjointed blade. For example, considering a disjointed blade with two sections, the first section may extend from the cone proximal boundary to the cone distal boundary. The second section may be disposed on a radial plane behind the first section, with respect to the direction of rotation of the bit, and extend from a location radially inward from the cone distal boundary and extend to full gage. Thus, a portion of the second section overlaps or trails the first section. Examples of various configurations of drill bits formed in accordance with embodiments of the present disclosure are described in more detail below.
Referring now to
Three secondary blades 996 are spaced uniformly between each disjointed blade 990 around the bit face 991. The secondary blades 996 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in
Referring to
The second sections 1004 of all three disjointed blades 1000 are disposed primarily in the nose, shoulder, and gage regions of the bit face. In particular, the second sections 1004 begin at a location proximate the outer circumferential edge (666 in
As shown, the first section 1002 of the third disjointed blade 1000c extends out past the cone region and the second section 1004 starts proximate the outer circumferential edge (666 in
Three secondary blades 1006 are spaced between each disjointed blade 1000 around the bit face 1001. The secondary blades 1006 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in
Referring to
The first section 1102 of first disjointed blade 1000a is disposed primarily in the cone region of the bit face 1101. The second section 1104 of the first disjointed blade 1100a is disposed primarily in the nose, shoulder, and gage regions of the bit face. In particular, the second section 1104 begins at a location proximate the outer circumferential edge (666 in
The first section 1102 of the second disjointed blade 1100b is disposed primarily in the cone region of the bit face 1101. The second section 1104 of the second disjointed blade 1100b is disposed primarily in the nose, shoulder, and gage regions of the bit face 1101. In particular, the second section 1104 begins at a location proximate the outer circumferential edge (666 in
The first section 1102 of the third disjointed blade 1100c starts proximate the central axis A and extends into the nose region, but less than full gage. The second section 1104 of the third disjointed blade 1100c is disposed primarily in the nose, shoulder, and gage regions of the bit face. In particular, the second section 1004 begins at a location proximate the outer circumferential edge (666 in
Three secondary blades 1106 are spaced between each disjointed blade 1100 around the bit face 1101. The secondary blades 1106 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in
Referring now to
The first sections 1202 of first and second disjointed blades 1200a, 1200b are disposed primarily in the cone region of the bit face 1201. The second sections 1204 of the two disjointed blades 1200 are disposed primarily in the nose, shoulder, and gage regions of the bit face 1201. As shown, the second sections 1204 of the first and second disjointed blades 1200a, 1200b are disposed along a radial plane behind the radial plane of first section 1202, with respect to a direction of rotation of the bit, indicated at 1212. The solid (conventional) primary blade 1207 starts proximate the central axis A and extends to full gage.
Four secondary blades 1206 are spaced between disjointed blade 1200 and solid (conventional) primary blade 1207 around the bit face 1201. The secondary blades 1206 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in
Referring to
The second sections 1304 of the disjointed blades 1300 are disposed a selected distance away from the central axis A and extend to full gage. The second section 1304 of the disjointed blade 1300 is disposed along a radial plane behind the radial plane of first section 1302 with respect to a direction of rotation of the bit, indicated at 1310. As shown, the selected distance from the central axis A, at which the second sections 1304 start, is disposed behind the first section 1302 with respect to the direction of rotation 1313 of the bit. Therefore, first and second sections 1302, 1304 of disjointed blades 1300 overlap in their radial distance from central axis A. Accordingly, at least one cutter 1303 disposed on the second sections 1304 of the disjointed blades 1300 may trail at least one cutter 1303 disposed on the first sections 1302 of the disjointed blades 1300.
Three secondary blades 1306 are spaced between each disjointed blade 1300 around the bit face 1301. The secondary blades 1306 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in
Referring to
As shown, the second sections 1404 are disposed on a radial plane different from the radial plane of the first sections 1402. The third sections 1405 are disposed on a radial plane different from the radial planes of the first and second sections 1402, 1404. Further, as shown, the second sections 1404 trail the first sections 1402, and the third sections 1405 trail the second sections 1404. Thus, as shown, one or more disjointed sections of one or more of the disjointed blades may overlap in the radial distance from the central axis A.
Three secondary blades 1406 are spaced between each disjointed blade 1400 around the bit face 1401. The secondary blades 1406 start a distance D away from the central axis A and extend toward the periphery of the bit. In the embodiment shown in
Referring now to
In some embodiments, one or more elements may be disposed in the cone region of the bit face 1501 without a blade or other structure. Elements may include, for example, diamond impregnated inserts, tungsten carbide inserts, depth of cut limiters, or other elements configured to cut formation, reduce wear, or stabilize the bit. Additionally, the surface of the bit face 1501 in the cone region may include a layer of ultra hard material disposed thereon. One or more blades may be disposed on the bit face primarily in the nose, shoulder, and gage regions, outside the cone region. In particular, a plurality of blades may be angularly-spaced around the bit face, each extending from a selected distance from the central axis A to less than full gage or full gage.
As shown in
With reference to
Referring to
While reference to bits having three disjointed blades has been made, one of ordinary skill in the art will appreciate that bits having one or more disjointed blades may also be used without departing from the scope of embodiments disclosed herein. Additionally, one of ordinary skill in the art will appreciate that bits formed in accordance with embodiments of the present disclosure may have any number of secondary blades, even zero.
Disjointed blades formed in accordance with the present disclosure may include two or more discrete sections. In alternate embodiments, the surface of the bit may be slightly contoured or raised in between the two or more sections of a disjointed blade. For example, a disjointed blade may include a filleted relief between the axial ends of the sections. Such webbing or contouring between the sections of the disjointed blades may reduce blade cracking or crack propagation.
Advantageously, embodiments disclosed herein provide greater flexibility in addressing various aspects of bit performance, including bit balance and bit hydraulics. In particular, fixed cutter drill bits formed in accordance with embodiments disclosed herein may provide more stabile and/or balanced bits. Further, fixed cutter drill bits formed in accordance with embodiments disclosed here may provide increased bit hydraulics.
Embodiments of the present disclosure provide various blade configurations for a fixed cutter bit that may separate the mechanics of the cone region of the bit face from the nose, shoulder, and gage regions of the bit face. Advantageously, a bit in accordance with embodiments disclosed herein, can therefore be designed that may provide full coverage, bit stability, and improved bit hydraulics. Additionally, sections of disjointed blades formed in accordance with embodiments disclosed herein may be selected so as to provide depth of cut limits or control of the bit when drilling.
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 drill bit for drilling a borehole in a formation, the drill bit comprising:
- a bit body having a bit face comprising a cone region, a nose region, a shoulder region, and a gage region;
- at least one disjointed blade disposed on the bit face, the disjointed blade comprising: a first section beginning proximate a central axis of the bit and extending less than full gage, and a second section beginning a selected distance from the central axis and extending to full gage; and
- a plurality of cutting elements mounted on the at least one disjointed blade.
2. The drill bit of claim 1, further comprising at least one secondary blade, the secondary blade beginning a predetermined distance from the central axis and extending to full gage.
3. The drill bit of claim 1, wherein the disjointed blade further comprises a third section beginning a second selected distance from the central axis and extending less than full gage.
4. The drill bit of claim 1, wherein the second section is disposed on a radial plane of the first section.
5. The drill bit of claim 1, wherein the second section behind a radial plane of the first section.
6. The drill bit of claim 5, wherein a cutting element disposed on the second section trails a cutting element disposed on the first section.
7. The drill bit of claim 1, wherein the first section is primarily disposed in the cone region.
8. The drill bit of claim 3, wherein the second section is primarily disposed in the nose and shoulder regions and the third section is primarily disposed in the gage region.
9. A drill bit for drilling a borehole in a formation, the drill bit comprising:
- a bit body having a bit face comprising a cone region, a nose region, a shoulder region, and a gage region;
- at least one disjointed primary blade disposed on the bit face, the disjointed blade comprising: a first section disposed primarily in the cone region, and a second section disposed primarily in at least one of the nose, shoulder, and gage regions; and
- at least one cutting element disposed on the first section and at least one cutting element disposed on the second section.
10. The drill bit of claim 9, wherein the second section partially overlaps the first section in a radial direction.
11. The drill bit of claim 9, wherein the at least one disjointed primary blade further comprises a third section disposed primarily in at least one of the nose, shoulder, and gage regions.
12. The drill bit of claim 9, wherein the second section is disposed on a radial plane of the first section.
13. The drill bit of claim 11, wherein the third section is disposed on a radial plane of the first section.
14. A drill bit for drilling a borehole in a formation, the drill bit comprising:
- a bit body having a bit face comprising a cone region, a shoulder region, and a gage region;
- at least one blade disposed on the bit face, the blade beginning a selected distance from the central axis and extending to full gage;
- at least one cutting structure disposed on the bit face in the cone region; and
- at least one cutting element disposed on the at least one blade.
15. The drill bit of claim 15, wherein the at least one blade begins at an outer circumference of the cone region.
16. The drill bit of claim 15, wherein the at least one blade is disposed primarily in the nose, shoulder, and gage regions.
Type: Application
Filed: Jul 22, 2009
Publication Date: Jan 28, 2010
Applicant: SMITH INTERNATIONAL, INC. (Houston, TX)
Inventors: Geoffrey M. Johnson (Bixby, OK), Carl M. Hoffmaster (Houston, TX), Bala Durairajan (Houston, TX), Michael George Azar (The Woodlands, TX)
Application Number: 12/507,730
International Classification: E21B 10/43 (20060101); E21B 10/42 (20060101);