Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/08—Roller bits
  • E21B10/14—Roller bits combined with non-rolling cutters other than of leading-portion type
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/08—Roller bits
  • E21B10/22—Roller bits characterised by bearing, lubrication or sealing details

Definitions

• the disclosure described herein generally relates to is drill bits for use in drilling operations in subterranean formations. More particularly, the disclosure relates to hybrid drill bits, and apparatus and methods for increasing the strength of the support surfaces in such drill bits.
• Drill bits are frequently used in the oil and gas exploration and the recovery industry to drill well bores (also referred to as "boreholes") in subterranean earth formations.
• drill bits used in drilling well bores known in the art as “fixed cutter” drill bits and “roller cone” drill bits.
• Fixed cutter type drill bits include polycrystalline diamond compact
• drill bit typically include a bit body having an externally threaded connection at one end for connection to a drill string, and a plurality of cutting blades extending from the opposite end of the bit body. The cutting blades form the cutting surface of the drill bit. Often, a plurality of cutting elements, such as PDC cutters or other materials, which
• This plurality of cutting elements is used to cut through the subterranean formation during drilling operations when the drill bit is rotated by a motor or other rotational input device.
• roller cone bit typically includes a bit body with an externally threaded connection at one end, and a plurality of roller cones (typically three) attached at an offset angle to the other end of the drill bit, relative to the bit's centerline. These roller cones are able to rotate about bearings, and rotate individually with respect to the bit body.
• the roller bit 10 includes a bit body 12 having a longitudinal centerline 8 and having a threaded pin-type connector 14 at its upper end for incorporation of the bit body 12 into the lower end of a drill string (not shown).
• the bit body 12 has generally three downwardly depending legs (two shown at 16, 18) with a lubricant compensator 20 provided for each.
• Nozzles 22 are positioned between each of the adjacent legs to dispense drilling fluid during drilling. The drilling fluid is pumped down through the drill string and into a cavity (not shown) in the bit body 12.
• a roller is secured to the lower end of each of the three legs.
• the three roller cones 24, 25, and 26 are visible in Figure 1 secured in a rolling relation to the lower ends of the legs of bit body 12.
• the roller cone 24 is rotatably retained by bearings 27 on an axle 28, where the axle has an axle centerline 6 disposed at an angle to the longitudinal centerline 8 of the bit body.
• the axle 28 includes a journal 29 and a pilot pin 30 with a shoulder 31 formed between the journal 29 and the pilot pin 30.
• the diametrical surfaces of the journal 29 and pilot pin 30 are useful for supporting the roller cone in radial (bending) loading, and the surface of the shoulder, and at times the end surface of the pilot pin, is useful for supporting the roller cone in thrust (end) loading.
• the diameter and length of the journal, the diameter and length of the pilot pin, and size of the shoulder formed therebetween is constrained by the size and shape of the roller cone coupled thereto.
• a larger pilot pin diameter results in either having to shorten the overall length of the journal and/or pilot pin, or reducing the cone shell thickness, either of which can lead to failure.
• too small of a surface on the shoulder may cause a failure of the axle and roller cone interface.
• the roller cone 24 has a cutter body 32 that is typically formed of a suitably hardened steel.
• the cutter body 32 is substantially cone-shaped.
• a plurality of primary cutting elements 34, 36, 38 extend from the cutter body 32. When the cutter body 32 is rotated upon the axle 28, the primary cutting elements engage earth within a borehole and crush it.
• the plurality of cutting elements us may be one or a combination of milled steel teeth (called steel-tooth bits), tungsten carbide (or other hard-material) inserts (called insert bits), or a number of other formed and/or shaped cutting elements that are formed of materials having a hardness and strength suitable enough to allow for the deformation and/or cutting through of subterranean formations.
• a hard facing material is applied to the exterior of the cutting elements and/or other portions of the roller cone drill bit, to reduce the wear on the bit during operation and extend its useful working life.
• a cross section of the pilot pin and journal is not shown in the above patent, but is typically the same as a roller cone bit.
• journal and the pilot pin support a radial load along their respective lengths that acts transverse to the axle centerline, and the face between the journal and the pilot pin supports a thrust load that acts in parallel to the axle centerline.
• a rotatable cutter assembly is generally smaller for a given size of bit than a corresponding roller cone bit,
• the hybrid drill bit must allow for both the rotatable cutter assemblies as well as the adjacent fixed blade cutters.
• the journal and pilot pin about which the rotatable cutter assembly rotates is necessarily smaller, which can result in higher stresses for the same loads with the smaller area.
• the stresses on the rotatable cutter assembly itself dictate that a minimum of material remain on the shell thickness of the cutter assembly that restricts the size and length of both the journal and pilot pin. For example, increasing the pilot pin diameter requires a shorter pin to accommodate the larger diameter within the confines of the cutter assembly, or requires a thinner wall on the cutter assembly.
• the invention disclosed and taught herein are directed to an improved hybrid drill bit and associated elements having at least two frusto-conical cutter assemblies, each rotatable around separate axles on the bit, and at least two fixed blade cutters adjacent the frusto-conical cutter assemblies.
• the improved drill bit expands the pilot pin to journal diameter ratio within the body of the frusto-conical cutter assembly but within the confines of the allowable space of the frusto-conical cutter assembly.
• the disclosure provides a hybrid drill bit for use in drilling through subterranean formations, the hybrid drill bit comprising: a shank disposed about a longitudinal centerline and adapted to be coupled to a drilling string; at least two fixed cutter legs coupled to the shank; at least two fixed blade cutters fixedly coupled to the cutter legs distally from the shank, comprising a plurality of cutting elements extending from a surface of the blades; and at least two frusto-conical cutter assemblies coupled to the frusto-conical cutter legs distally from the shank and adjacent the fixed blade cutters and adapted to rotate relative to the shank about the axle centerline on the journal and pilot pin, the cutter assemblies comprising cutting elements extending from a surface of the assemblies.
• the axle of the frusto-conical cutter legs comprises a journal disposed about the axle centerline, the journal having a journal diameter; and a pilot pin coupled to the journal and extending along the axle centerline toward the longitudinal centerline, the pilot pin having a pilot pin diameter, the pilot pin diameter to journal diameter having a ratio of equal to or greater than 0.58.
• the disclosure provides a hybrid drill bit for use in drilling through s subterranean formations, the hybrid drill bit comprising: a shank disposed about a longitudinal centerline and adapted to be coupled to a drilling string; at least two fixed cutter legs coupled to the shank; at least two fixed blade cutters fixedly coupled to the cutter legs distally from the shank, comprising a plurality of cutting elements extending from a surface of the blades; and at ie least two frusto-conical cutter legs coupled to the shank, comprising an axle with an axle centerline extending at an angle to the longitudinal centerline and toward the longitudinal centerline.
• the axle comprises a journal disposed about the axle centerline, the journal having a journal diameter; and a pilot pin coupled to the journal and extending along the axle centerline toward the
• the pilot pin having a pilot pin diameter, the pilot pin diameter to journal diameter having a ratio of equal to or greater than 0.58.
• Figure 1 illustrates a side view of a typical roller cone bit.
• Figure 2 illustrates a cross sectional side view of a typical roller cone bit a? journal and pilot pin configuration.
• Figure 3 illustrates an exemplary side view of a hybrid drill bit.
• Figure 4 illustrates an exemplary bottom view of a hybrid drill bit.
• Figure 5 illustrates a cross sectional side view of an exemplary enlarged pilot pin to journal diameter configuration according to the disclosure.
• Figure 6 illustrates a cross sectional side view of another exemplary enlarged pilot pin to journal diameter configuration according to the disclosure.
• Couple in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims.
• the terms “couple,” “coupled,” “coupling,” “coupler,” and like terms are used broadly herein and may include any method or device for securing, binding, bonding, fastening, attaching, joining, inserting therein, forming thereon or therein, communicating, or so otherwise associating, for example, mechanically, magnetically, electrically, chemically, directly or indirectly with intermediate elements, one or more pieces of members together and may further include without limitation integrally forming one functional member with another in a unity fashion.
• the coupling may occur in any direction, including rotationally.
• Applicants have created an improved hybrid drill bit and associated elements with an expanded pilot pin to journal diameter ratio within the body of the frusto-conical cutter assembly, where the hybrid drill bit includes at least two frusto-conical cutter assemblies, each rotatable around separate axles on the 20 bit, and at least two fixed blade cutters adjacent the frusto-conical cutter assemblies.
• Figure 3 illustrates an exemplary side view of a hybrid drill bit.
• Figure 4 illustrates an exemplary bottom view of a hybrid drill bit.
• Figure 5 illustrates an exemplary enlarged pilot pin to journal diameter configuration according to 25 the disclosure.
• Figure 6 illustrates another exemplary enlarged pilot pin to journal diameter configuration according to the disclosure. The figures will be described in conjunction with each other.
• a hybrid drill bit 50 has a longitudinal centerline 52 that defines an axial center of the hybrid drill bit.
• a shank 54 is formed on one end of the hybrid drill bit ⁇ ⁇ . ⁇ and is designed to be coupled to a drill string of tubular material (not shown) with threads according to standards promulgated for example by the American Petroleum Institute (API).
• At least two fixed cutter legs bit legs 56 extend downwardly from the shank 54 relative to a general orientation of the bit inside a borehole. The fixed cutter legs 56 transition into fixed blade cutters 58 at an end of the hybrid drill bit distal from the shank 54.
• a plurality of fixed blade cutting elements 60, 62 are arranged and secured to
• the fixed blade cutting elements 60, 62 comprise a polycrystalline diamond (PCD) layer or table on a rotationally leading face of a supporting substrate, the diamond layer or table providing a cutting face having a cutting edge at a v ⁇ periphery thereof for engaging the formation.
• PCD polycrystalline diamond
• the term PCD is used broadly and includes other materials, such as thermally stable polycrystalline diamond
• TSP TSP wafers or tables mounted on tungsten carbide substrates, and other, similar superabrasive or super-hard materials, such as cubic boron nitride and diamond-like carbon.
• Fixed-blade cutting elements 60, 62 may be brazed or is otherwise secured in recesses or "pockets" on each fixed blade cutter 58 so that their peripheral or cutting edges on cutting faces are presented to the formation.
• the hybrid drill bit 50 further includes at least two frusto-conical cutter legs 64 and frusto-conical cutter assemblies 72 coupled to such legs.
• the frusto-conical cutter legs 64 and frusto-conical cutter assemblies 72 coupled to such legs.
• conical cutter legs 64 in similar fashion to the fixed cutter legs 56, extend downwardly from the shank 54 relative to a general orientation of the bit inside a borehole.
• Each of the frusto-conical cutter legs 64 transition into an axle 66 at the legs' distal end.
• the axle 66 has an axle centerline 67 about which the axle is symmetrically formed.
• the axle centerline 67 is generally disposed at
• axle centerline 67 can intersect the longitudinal centerline 6.
• the axle 66 generally forms two portions — a journal 68 disposed at a base of the axle, and a pilot pin 70 adjacent the journal and extending axially along the axle centerline 67.
• a shoulder 71 is established as a result of the different diameters between the journal 68 and the pilot pin 70.
• the journal, pilot pin, ? and shoulder support a frusto-conical cutter assembly 72 rotatably disposed about the journal and pilot pin.
• a frusto-conical cutter assembly 72 is generally coupled to each axle 66.
• the frusto-conical cutter assembly 72 generally has a truncated nose section 73 compared to a typical roller cone bit illustrated in Figure 2.
• & cutter assembly 72 is adapted to rotate around the axle 66 when the hybrid drill bit 50 is being rotated by the drill string through the shank 52.
• a plurality of cutting elements 74, 75 is coupled to a surface 77 of the cutter assembly 72.
• At least some of the cutting elements are generally arranged on the frusto-conical cutter assembly 72 in a circumferential row thereabout.
• a is minimal distance between the cutting elements will vary according to the application and bit size, and may vary from cutter assembly to cutter assembly, and/or cutting element to cutting element.
• Some cutting elements can be arranged "randomly" on the surface of the cutter assembly.
• the cutting elements can include tungsten carbide inserts, secured by interference
• the cutting elements 20 fit into bores in the surface of the cutter assembly, milled- or steel-tooth cutting elements having hard faced cutting elements integrally formed with and protruding from the surface of the cutter assembly, and other types of cutting elements.
• the cutting elements may also be formed of, or coated with, superabrasive or super-hard materials such as polycrystalline diamond, x cubic boron nitride, and the like.
• the cutting elements may be chisel-shaped as shown, conical, round, or ovoid, or other shapes and combinations of shapes depending upon the application.
• the cutting elements 60, 62 of the fixed blade cutter 58 and the cutting elements 74, 75 of the frusto-conical cutter assembly 72 30 combine to define a congruent cutting face in the leading portions of the hybrid drill bit profile.
• the cutting elements 74, 75 of the frusto-conical cutter assembly 72 crush and pre- or partially fracture subterranean materials in a formation in the highly stressed leading portions, easing the burden on the cutting elements 60, 62 of the fixed blade cutter 58.
• a ball bearing 80 can assist in maintaining rotational capacity of the cutter assembly around the axle.
• One or more sealed or unsealed radial bearings 82, 84 provide a contact length along the axle centerline that can assist the cutter assembly 72 in being rotated about the axle 66 and support radial (bending) loading.
• the bearings can include sleeve bearing, roller bearings, floating bushings, shrink fit sleeves, and other bearings types and materials.
• a thrust bearing 86 can be placed on the shoulder or an end of the pilot pin to provide thrust load capacity and facilitate the rotation of the frusto-conical cutter assembly about the axle as the cutter assembly contacts the shoulder or the end of the pilot pin.
• the cutter assembly 72 generally includes a seal 88 disposed between the axle 66 and an inside cavity of the frusto-conical cutter assembly.
• the seal 88 can be from well-known sealing systems, such as elastomeric seals and metal face seals.
• hybrid drill bit such as back up cutters, wear resistant surfaces, nozzles that are used to direct drilling fluids, junk slots that provides a clearance for cuttings and drilling fluid, and other generally accepted features of a drill bit are deemed within the knowledge of those with ordinary skill in the art and do not need further description.
• journal, pilot pin, and shoulder are stressed in radial and thrust loading when the hybrid drill bit is used to drill the subterranean formations. It is important to enlarge the diameters of the journal and pilot pin in relation to the shoulder, and lengthen the journal and pilot pin without compromising the integrity of the frusto- conical cutter assembly by having too thin of a shell thickness on the cutter assembly or too small of supporting surfaces on the axle.
• Conventional design for roller cone bits such as shown in Figures 1 and 2 has well established certain restrictions on the size of the journal, pilot pin, and shoulder for a given size of roller cone.
• the size has been limited to the shape and configuration of the roller cone and minimum shell thickness to s support the loads on the roller cone.
• the relative size of the pilot pin diameter to the journal diameter can be expressed as a ratio.
• the typical ratio is about 0.50 and is less than 0.56. Larger ratios typically compromise the bearing length for a given optimum journal diameter or cause an unwanted reduction in shell thickness.
• the present inventors have reevaluated from ground up the journal and pilot pin diameters and resultant ratios relative to a frusto-conical cutter assembly shell thickness and have discovered that the ratios can be altered for the frusto-conical cutter assembly. This adjustment is especially important 2 ⁇ because on a hybrid drill bit, the frusto-conical cutter assembly is generally smaller for a given size of hybrid drill bit than a corresponding roller cone bit.
• the hybrid drill bit must allow for both the frusto-conical cutter assemblies and the adjacent fixed blade cutters, resulting in a smaller journal and pilot pin and higher stresses for the same loads.
• the ratio of the pilot pin diameter to the journal diameter can be increased to at least 0.58 up to and including 1.0, including P:J ratios of about 0.60, about 0.62, about 0.64, about 0.66, about 0.68, about 0.70, about 0.72, about 0.74, about 0.76, about 0.78, about 0.80, about 0.82, about 0.84, about 0.86, about
• a P:J ratio ranging from about 0.71 to about 0.95, or from about 0.83 to about 0.99, inclusive.
• the pilot pin 70 becomes the same diameter as the journal 68 and the axle portions effectively merge into a continuous surface.
• the shoulder 71 decreases in surface area.
• the pilot pin itself can support thrust loads on the end of the pilot pin that interfaces with the frusto-conical cutter assembly.
• a thrust bearing 86 can be included between the pilot pin 70 and the cutter assembly 72.
• some ratios can be greater than 1.0, where the pilot pin is greater in diameter than the journal.
• radial bearings can be included if present.
• the thickness of the bearing that supports the radial load can be calculated into the effective diameter of the journal and compared with the pilot pin diameter.
• a radial bearing 84 on the pilot pin with a contact length along the axle centerline can effectively create a larger pilot pin and thus larger pilot pin diameter to be calculated in the ratio.

Applications Claiming Priority (3)

Publications (3)

Family

ID=42264427

Family Applications (1)

Country Status (7)

Families Citing this family (17)

Citations (3)

Family Cites Families (109)

• 2009
  • 2009-06-09 US US12/481,410 patent/US20100155146A1/en not_active Abandoned
  • 2009-12-15 RU RU2011129565/03A patent/RU2541414C2/ru not_active IP Right Cessation
  • 2009-12-15 WO PCT/US2009/067969 patent/WO2010080380A1/en active Application Filing
  • 2009-12-15 MX MX2011005857A patent/MX2011005857A/es not_active Application Discontinuation
  • 2009-12-15 EP EP09837870.6A patent/EP2358969B1/de not_active Not-in-force
  • 2009-12-15 CA CA2747434A patent/CA2747434A1/en not_active Abandoned
  • 2009-12-15 BR BRPI0922569A patent/BRPI0922569A2/pt not_active IP Right Cessation

Patent Citations (3)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events