EP0605151A1 - Drehbohrmeissel mit Stabilisierungselementen - Google Patents

Drehbohrmeissel mit Stabilisierungselementen Download PDF

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Publication number
EP0605151A1
EP0605151A1 EP93310193A EP93310193A EP0605151A1 EP 0605151 A1 EP0605151 A1 EP 0605151A1 EP 93310193 A EP93310193 A EP 93310193A EP 93310193 A EP93310193 A EP 93310193A EP 0605151 A1 EP0605151 A1 EP 0605151A1
Authority
EP
European Patent Office
Prior art keywords
cutting
drill bit
rotary drill
bit body
elements
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP93310193A
Other languages
English (en)
French (fr)
Inventor
Kelly Hollister
David Truax
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Camco Drilling Group Ltd
Original Assignee
Camco Drilling Group Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Camco Drilling Group Ltd filed Critical Camco Drilling Group Ltd
Publication of EP0605151A1 publication Critical patent/EP0605151A1/de
Withdrawn legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B10/00—Drill bits
    • E21B10/46—Drill bits characterised by wear resisting parts, e.g. diamond inserts
    • E21B10/56—Button-type inserts
    • E21B10/567—Button-type inserts with preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts

Definitions

  • the invention relates to rotary drill bits for use in drilling or coring holes in subsurface formations, and of the kind comprising a bit body having a shank for connection to a drill string, a plurality of cutting elements mounted at the surface of the bit body, and a passage in the bit body for supplying drilling fluid to the surface of the bit body for cooling and/or cleaning the cutting elements, at least some of the cutting elements each comprising a preform cutting element having a superhard front cutting face.
  • the invention is particularly, but not exclusively, applicable to drill bits of this kind in which the cutting elements comprise preforms having a thin cutting table of polycrystalline diamond bonded to a substrate of cemented tungsten carbide.
  • Various methods may be used for mounting such cutting elements on the bit body but such methods, and the general construction of bits of the kind to which the invention relates, are well known and will not therefore be described in detail.
  • the drill bit When drilling deep holes in subsurface formations, it often occurs that the drill bit passes through a comparatively soft formation and strikes a significantly harder formation. Also there may be hard occlusions within a generally soft formation. When a bit using preform cutters meets such a hard formation the cutting elements may be subjected to very rapid wear. Preform cutting elements may also be subject to impact damage, for example when a new drill bit is first tripped into an existing borehole, when it may impact on the bottom of the borehole.
  • each abrasion element comprises a plurality of particles of superhard material, such as polycrystalline diamond, embedded in a stud-like carrier element one end of which is received in a socket in the bit body and the other end of which protrudes from the bit body.
  • bits incorporating such abrasion elements have been very successful, since the abrasion elements supplement, or take over entirely, the cutting action of a cutting element which has become excessively worn or which has failed through fracture.
  • the abrasion elements may share the loads which would otherwise be borne solely by the cutting elements as a result of the weight-on-bit during drilling, or impact of the drill bit with the bottom of the borehole.
  • the abrasion elements may serve as depth stops to limit the depth of cut effected by the primary cutting elements.
  • the present invention is based on the realisation that, in some circumstances, it may be advantageous to employ, on a rotary drill bit of the kind first referred to, back-up elements which are formed of a material which is less hard and abrasive than the known abrasion elements comprising particles of superhard material embedded in a stud-like element.
  • the invention may have the incidental advantage of such back-up elements being less costly than abrasion elements of the known kind.
  • U.S. Patent Specification No. 5090492 discloses a rotary drill bit in which there is provided behind each of certain of the cutting elements a stabilising projection integrally formed on the surface of the bit body.
  • Each projection is of peripherally elongated configuration and is circumferentially aligned with an associated cutting element so as to snugly enter and engage the side walls of the formation groove produced by the aligned cutting element.
  • the purpose of the stabilising projections is, by snugly engaging the side walls of the formation groove, to provide substantial resistance against lateral displacement or vibration of the drill bit.
  • peripheral elongation of the projections will necessarily result in the formation of a substantial peripherally elongated wear flat on each projection as drilling proceeds, and such a large wear flat will provide very substantial frictional restraint to rotation of the drill bit, necessitating substantial increase in the rotational energy which must be imparted to the drill string.
  • the present invention overcomes this disadvantage, while at the same time maintaining significant resistance against lateral displacement or vibration of the drill bit.
  • the back-up elements are spaced inwardly of the cutting profile defined by the cutting elements,
  • the cutting profile of the cutting elements is defined to mean a generally smooth notional surface which is swept out by the cutting edges of the cutting elements as the bit rotates without axial movement.
  • the back-up elements Since the material of the back-up elements is less hard than that of the superhard material of the cutting elements, the back-up elements wear away more easily than the cutting elements, should the back-up elements come into engagement with the formation, and thus the frictional restraint to rotation caused by the back-up elements is reduced.
  • the wear flat which forms on each back-up element is also limited in area by the fact that the minimum dimension of the formation-engaging surface of each element is less than the width of its associated cutting element in a generally radial direction. Since the frictional restraint is dependent on the area of the wear flat at any particular time, the frictional restraint, as the wear flat develops, is dependent on the geometry of the back-up element and may thus be predetermined by appropriate design of that geometry.
  • each back-up element in the circumferential direction may be significantly less than the maximum dimension in a radial direction.
  • the back-up element may then provide substantial restraint against radial displacement or vibration without creating a substantial wear flat and substantially increasing the frictional restraint to rotation.
  • Each back-up element may be in the form of an elongate stud-like insert having one end received within a socket in the bit body and the other end protruding from the bit body.
  • the insert may, for example, be formed from sintered or cemented tungsten carbide or other refractory material, or from solid infiltrated matrix material, such as particulate tungsten carbide infiltrated with a copper binder.
  • the bit body may be machined from metal, such as steel, or may be moulded from solid infiltrated matrix material in a powder metallurgy process, of well known kind. In the latter case each back-up element may comprise a projection of matrix material integrally moulded with the bit body.
  • the back-up element is in the form of a stud-like insert
  • at least the end of the insert received within the socket in the bit body is preferably generally cylindrical and of circular cross-section.
  • each back-up element may be domed, for example hemispherically domed.
  • the projecting portion of the back-up element may taper as it extends away from the bit body. In this case it preferably tapers more in a generally radial direction than it does in a generally circumferential direction, so that the projecting portion of the back-up element is generally chisel-shaped.
  • each back-up element may be substantially the same as the outer profile of the associated cutting element when viewed in the same circumferential direction, the dimension of the formation-engaging surface of the back-up element in the circumferential direction being less than the width of the cutting element.
  • Each back-up element may be located at substantially the same radial distance from the axis of rotation of the bit as its associated cutting element.
  • At least the portion of the back-up element which protrudes from the bit body may taper outwardly, in a circumferential direction and/or in a radial direction, as it extends away from the bit body.
  • the minimum dimension of the formation-engaging surface of the back-up element is not necessarily less than the width of the associated cutting element, as in the arrangements previously referred to.
  • the cross-sectional shape of the back-up element may be correlated to the cross-sectional shape of the associated cutting element in such manner that the combined area of the wear flats on the back-up element and the cutting element remains substantially constant, or varies within a predetermined limited range, as wear proceeds.
  • the rotary bit body has a leading end face 10 formed with a plurality of blades 11 upstanding from the surface of the bit body so as to define between the blades channels 12 for drilling fluid.
  • the channels 12 lead outwardly from nozzles 13 to which drilling fluid passes through a passage (not shown) within the bit body. Drilling fluid flowing outwardly along the channels 12 passes to junk slots 14 in the gauge portion of the bit.
  • each blade 11 Mounted on each blade 11 is a row of cutting elements 15.
  • the cutting elements project into the adjacent channels 12 so as to be cooled and cleaned by drilling fluid flowing outwardly along the channels from the nozzles 13 to the junk slots 14.
  • Spaced rearwardly of the three or four outermost cutting elements on each blade are back-up elements 16.
  • each back-up element lies at substantially the same radial distance from the axis of rotation of the bit as it associated cutting element, although other configurations are possible.
  • each cutting element 15 is a circular preform tablet comprising a front thin hard facing cutting table 17 of polycrystalline diamond bonded to a thicker substrate 18 of less hard material, such as cemented tungsten carbide.
  • the cutting element 15 is bonded, in known manner, to an inclined surface on a generally cylindrical stud 19 which is received in a socket in the bit body 10.
  • the stud 19 may be formed from cemented tungsten carbide and the bit body 10 may be formed from steel or from solid infiltrated matrix material.
  • Each back-up element 16 comprises a generally cylindrical insert having a portion 20 which is received in a socket in the bit body 10 spaced rearwardly of the stud 19.
  • the back-up element 16 is formed wholly from material which is less hard than the polycrystalline diamond, or other superhard material, of the cutting element. Suitable materials are cemented tungsten carbide or solid infiltrated matrix material of the kind used for moulded bit bodies.
  • the back-up element has a hemispherically domed projecting portion 21 which projects beyond the surface of the bit body 10.
  • the outer extremity of the projecting portion 21 of the back-up element is spaced inwardly of the cutting profile defined by the cutting elements 15, such profile being indicated by the chain line 22.
  • the back-up elements 16 will serve to limit the depth of cut which may be effected by the cutting elements 15 and will also serve to a certain extent to limit impact damage to the cutting elements.
  • each back-up element 16 may serve to reduce radial vibration of the drill bit, but at the same time the configuration of each back-up element 16 is such that only a comparatively small wear flat is formed. Since the projecting portion 21 of the back-up element is hemispherically domed the formation-engaging surface of the back-up element will initially comprise, at most, only a narrow strip of the domed surface, indicated in dotted lines at 23 in Figure 2, which extends for 180° or less around the projecting portion 21 in a radial direction and which is narrow in the circumferential direction (with respect to the drill bit). As a wear flat develops on the back-up element the width of the surface portion 23 will increase in the circumferential direction but its dimension in this direction will always be less than the width of the cutting element 15 in the radial direction, in accordance with the present invention.
  • the frictional restraint to rotation caused by the back-element depends only on the area of the wear flat (for a given set of operating parameters) and is not subject to variations in the composition of the wear flat.
  • the geometry of the back-up element may thus be selected to give a predictable pattern of frictional restraint as wear proceeds.
  • the effect of the back-up element may therefore be accurately controlled with respect to the requirements of the associated cutting element. This control of the frictional restraint resulting from the back-up elements also enables control of the heat generated.
  • Figure 3 shows an alternative arrangement in which the bit body is moulded from solid infiltrated matrix material, such as powdered tungsten carbide infiltrated with a copper binder.
  • the back-up element 24 comprises a generally hemispherically domed projection integrally moulded with the surface of the bit body.
  • the geometrical arrangement of the projection 24 with respect to the cutting element is similar to that of the projecting portion 21 of the insert 20 in the arrangement of Figure 2 and the shape of its formation-engaging surface will be similar.
  • Figure 4 is a diagrammatic front elevation of the cutting element 15 and stud 19 in the arrangement of Figure 2
  • Figure 5 is a front elevation of the domed insert 21.
  • the outer peripheral shape of the insert 20 is generally of the same width as the cutting element 15 and the radius of the domed extremity is similar to the radius of the cutting element 15 also.
  • Figure 6 is a similar view to Figures 2 and 3 showing a different form of back-up insert 25.
  • the projecting portion 26 of the insert is tapered both in the circumferential direction, as shown in Figure 6, and in the radial direction, as shown in Figure 7.
  • the insert tapers more in the radial direction than it does in the circumferential direction, with respect to the drill bit, so that the projecting portion 26 of the insert is generally chisel-shaped.
  • This ensures that the formation-engaging surface of the projecting portion 26 of the element has a minimum dimension which is less than the width of the associated cutting element 15 in a generally radial direction, in accordance with the invention.
  • Such arrangement means that the wear flat, as the insert is worn down by engagement with the formation, remains comparatively small in area while the insert still remains effective for protecting the cutting element and for providing radial stability to the drill bit.
  • Figures 8 and 9 show a modified version of the arrangement of Figures 6 and 7, in which the insert 25 has been rotated through 90°, so that the wider aspect of the chisel-shaped projecting portion extends generally radially, instead of circumferentially.
  • Figure 10 One such set of graphs is shown in Figure 10 where the cross-sectional area of the cutting element or back-up element (in square millimetres) parallel to the formation is plotted against the distance from the tip or outermost extremity of the element (in millimetres).
  • Figure 10 assumes that the tip of the back-up element lies on the cutting profile, and is thus at the same level as the cutting edge of the cutting element.
  • the curve indicated at 27 relates to a polycrystalline diamond cutter of a typical form used in drag type drill bits.
  • Curve 28 relates to a prior art back-up element of the kind comprising a cemented tungsten carbide post having a 118° conical projecting portion impregnated with particles of natural diamond or other superhard material.
  • Curves 29 and 30 relate to generally chisel-shaped inserts of cemented tungsten carbide, for example inserts of the kind shown in Figures 6-9, which may be standard tungsten carbide inserts of a kind used as the primary cutting elements in roller cone bits.
  • the prior art back-up element represented by curve 28, will produce a much larger wear flat for a given depth of wear than either of the chisel-shaped inserts indicated by curves 29 and 30.
  • the smaller wear flat generated by the latter inserts may create less resistance to rotation of the drill bit than that created by the prior art back-up element. In addition to this, the if frictional engagement is lower it will generate less heat.
  • Figures 11-13 are graphs generally similar to Figure 10, but showing the situation where the outer extremity of the back-up element is spaced inwardly from the cutting profile by a predetermined amount. In each case, therefore, a certain amount of wear of the cutting element occurs, and a wear flat develops, before the back-up element engages the formation and formation of a wear flat on the back-up element begins.
  • the back-up element is spaced 1.5 mm inwardly from the cutting profile, in Figure 12 it is spaced 1 mm from the profile, and in Figure 13 it is spaced 0.5 mm inwardly from the cutting profile.
  • the frictional restraint to rotation depends only on the area of the wear flat and not on the composition of the wear flat at any instant, since the composition of the material of the wear flat is uniform. Consequently, it is possible to control the frictional resistance to rotation, and the generation of heat, solely by controlling the geometry of the back-up elements.
  • Figure 14 illustrates another form of back-up element in accordance with the invention.
  • the back-up element comprises a post 31 of cemented tungsten carbide, solid infiltrated matrix or other non-superhard material.
  • the post is generally cylindrical and circular in cross-section and has a portion 32 which projects from the surface of the bit body 10.
  • the projecting portion 32 comprises a main part-spherically domed portion 33 at the centre of which is an additional part-spherical projecting portion 34 of smaller radius.
  • the size of the central portion 34 may be so selected that normally only this central portion is worn away during the normal life of the cutting element 15. During the life of the back-up element, therefore, it presents only a comparatively small surface wear flat to the formation and, in accordance with the present invention, the minimum dimension of the formation-engaging surface of the back-up element will always be significantly less than the width of the cutting element 15 in the radial direction.
  • the comparatively small surface-engaging portion 34 has the necessary strength to prevent failure of the element in use, due for example to impact forces in the downhole environment.
  • the back-up element 35 shown in side view in Figure 15 and front view in Figure 16 is so shaped that it tapers outwardly as it extends away from the bit body 10, with the result that the cross-sectional area of the back-up element decreases with distance from the outer extremity of the element.
  • the area of the wear flat presented by the element 35 to the formation will decrease as wear proceeds. Since the area of the wear flat presented by the cutting element 15 increases as wear proceeds, it will be appreciated that, by suitable selection of the geometric shape of the back-up element 35, it is possible to correlate the development of the two wear flats so that the combined area of the two wear flats remains substantially constant, or varies only over a predetermined limited range, as wear proceeds.
  • the back-up element or at least the portion thereof which engages the formation during the normal life of the bit, is formed wholly from a material which is less hard than the superhard material of the associated cutting element.
  • the back-up elements described above will normally be made of cemented tungsten carbide or solid infiltrated matrix material, the invention does not exclude the use of other materials which are non-superhard, and any other suitable materials may be employed provided, of course, that they have the other well known characteristics required for elements which must be mounted in a drill bit and must survive in the harsh downhole environment.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Geology (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Earth Drilling (AREA)
EP93310193A 1992-12-31 1993-12-16 Drehbohrmeissel mit Stabilisierungselementen Withdrawn EP0605151A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9227135 1992-12-31
GB9227135A GB2273946B (en) 1992-12-31 1992-12-31 Improvements in or relating to rotary drill bits

Publications (1)

Publication Number Publication Date
EP0605151A1 true EP0605151A1 (de) 1994-07-06

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EP93310193A Withdrawn EP0605151A1 (de) 1992-12-31 1993-12-16 Drehbohrmeissel mit Stabilisierungselementen

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EP (1) EP0605151A1 (de)
GB (1) GB2273946B (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2330599A (en) * 1997-10-21 1999-04-28 Diamond Products International Improvements in or relating to drill bits
GB2378718A (en) * 2001-08-13 2003-02-19 Baker Hughes Inc Drill bit for subterranean formations having bearing elements
US7360608B2 (en) 2004-09-09 2008-04-22 Baker Hughes Incorporated Rotary drill bits including at least one substantially helically extending feature and methods of operation

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5505273A (en) * 1994-01-24 1996-04-09 Smith International, Inc. Compound diamond cutter
EP0707130B1 (de) * 1994-10-15 2003-07-16 Camco Drilling Group Limited Drehbohrmeissel
GB2294069B (en) * 1994-10-15 1998-10-28 Camco Drilling Group Ltd Improvements in or relating to rotary drills bits
US6298930B1 (en) * 1999-08-26 2001-10-09 Baker Hughes Incorporated Drill bits with controlled cutter loading and depth of cut
US6460631B2 (en) 1999-08-26 2002-10-08 Baker Hughes Incorporated Drill bits with reduced exposure of cutters
US6568492B2 (en) 2001-03-02 2003-05-27 Varel International, Inc. Drag-type casing mill/drill bit
US8141665B2 (en) 2005-12-14 2012-03-27 Baker Hughes Incorporated Drill bits with bearing elements for reducing exposure of cutters
US7814997B2 (en) 2007-06-14 2010-10-19 Baker Hughes Incorporated Interchangeable bearing blocks for drill bits, and drill bits including same
US8943663B2 (en) 2009-04-15 2015-02-03 Baker Hughes Incorporated Methods of forming and repairing cutting element pockets in earth-boring tools with depth-of-cut control features, and tools and structures formed by such methods
US9309723B2 (en) 2009-10-05 2016-04-12 Baker Hughes Incorporated Drill bits and tools for subterranean drilling, methods of manufacturing such drill bits and tools and methods of directional and off center drilling

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4718505A (en) * 1984-07-19 1988-01-12 Nl Petroleum Products Limited Rotary drill bits
EP0291314A2 (de) * 1987-05-13 1988-11-17 Reed Tool Company Limited Schneidelement und Drehbohrmeissel mit einem derartigen Element
EP0370717A1 (de) * 1988-11-21 1990-05-30 Smith International, Inc. Diamant-Fräsmeissel für weiche Formationen
US5090492A (en) * 1991-02-12 1992-02-25 Dresser Industries, Inc. Drill bit with vibration stabilizers

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5265685A (en) * 1991-12-30 1993-11-30 Dresser Industries, Inc. Drill bit with improved insert cutter pattern

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4718505A (en) * 1984-07-19 1988-01-12 Nl Petroleum Products Limited Rotary drill bits
EP0291314A2 (de) * 1987-05-13 1988-11-17 Reed Tool Company Limited Schneidelement und Drehbohrmeissel mit einem derartigen Element
EP0370717A1 (de) * 1988-11-21 1990-05-30 Smith International, Inc. Diamant-Fräsmeissel für weiche Formationen
US5090492A (en) * 1991-02-12 1992-02-25 Dresser Industries, Inc. Drill bit with vibration stabilizers

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5992548A (en) * 1995-08-15 1999-11-30 Diamond Products International, Inc. Bi-center bit with oppositely disposed cutting surfaces
GB2330599A (en) * 1997-10-21 1999-04-28 Diamond Products International Improvements in or relating to drill bits
GB2330599B (en) * 1997-10-21 2001-11-14 Diamond Products Internat Inc Stability enhanced bi-centre bit
GB2378718A (en) * 2001-08-13 2003-02-19 Baker Hughes Inc Drill bit for subterranean formations having bearing elements
US6659199B2 (en) 2001-08-13 2003-12-09 Baker Hughes Incorporated Bearing elements for drill bits, drill bits so equipped, and method of drilling
BE1015202A5 (fr) * 2001-08-13 2004-11-09 Baker Hughes Inc Structure de forage, procede de forage avec celle-ci et procede de conception de la structure.
GB2378718B (en) * 2001-08-13 2005-06-01 Baker Hughes Inc Bearing elements for drill bits, drill bits so equipped,method of drilling and method of drill bit design
US7360608B2 (en) 2004-09-09 2008-04-22 Baker Hughes Incorporated Rotary drill bits including at least one substantially helically extending feature and methods of operation
US8011275B2 (en) 2004-09-09 2011-09-06 Baker Hughes Incorporated Methods of designing rotary drill bits including at least one substantially helically extending feature

Also Published As

Publication number Publication date
GB2273946B (en) 1996-10-09
GB2273946A (en) 1994-07-06
GB9227135D0 (en) 1993-02-24

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