HYBRID BIT WITH ROLLER CONES AND DISCS
A hybrid drill bit includes a bit body having a central bit body axis, a roller cone at an end of the bit body and rotatably coupled to the bit body about a roller cone axis, and a disc at the end of the bit body and rotatably coupled to the bit body about a disc axis. The roller cone axis extends toward the central bit body axis. The disc axis is transverse to a radial of the central bit body axis through a center of the disc, and the disc includes a plurality of disc cutters.
The present disclosure relates to hybrid drill bits for drilling a wellbore in a formation, and more particularly to hybrid drill bits with roller cones and discs.
A hybrid drill bit for drilling wellbores generally includes more than one type of cutting structure or cutting element at a drill end of the bit. Cutting structures and cutting elements encounter a variety of formations, objects, and surfaces during drilling, such as hard and soft rock formations, cement plugs and well stops, well tools, and/or other objects and surfaces in a wellbore. Because cutting elements and cutting structures remove material by different mechanisms, e.g., shearing, crushing, cracking, or a combination thereof, some are better suited to cutting particular materials than others.
Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTIONReferring first to
A drill string 22 is shown as having been lowered from the surface 16 into the wellbore 12. In some instances, the drill string 22 is a series of jointed lengths of tubing coupled together end-to-end and/or a continuous (i.e., not jointed) coiled tubing. The drill string 22 includes one or more well tools, including a bottom hole assembly 24. The bottom hole assembly 24 can include, for example, a drill bit. In the example shown, the wellbore 12 is being drilled. The wellbore 12 can be drilled in stages, and the casing 20 may be installed between stages.
Referring to
Various types of cutting elements and cutting structures may be provided on a hybrid drill bit. In the example shown in
The roller cone arms 110 and disc arms 114 are shown attached to the bit body 102 with fasteners 116 such that the roller cone arms 110 and disc arms 114 are removable from the bit body 102. In some instances, the roller cone arms 110 and disc arms 114 are an extension of the bit body 102, are welded to or cast with the bit body 102, and/or are connected to the bit body 102 in another way.
In some instances, the roller cones 108 rotate on spindles (not shown) extending from the bit body 102 or roller cone arms 110 along the roller cone axes B-B. Similarly, in some instances, the discs 112 rotate on spindles (not shown) extending from the bit body 102 or disc arms 114 along the disc rotation axes C-C. The roller cones 108 and discs 112 can attach to the spindles via a bearing system to allow rotation of the roller cones 108 about the cone rotation axes B-B and/or discs 112 about the disc axes C-C. The bearing system can include, for example, a seal, ball bearings, a lubrication system, and/or a pressure compensation system.
The roller cones 108 can operate at a number of positions and configurations. In the example shown, the roller cones 108 are radially disposed near an outer lateral periphery of the drill end 106. In some instances, the roller cones 108 are disposed more inward toward the central bit body axis A-A, more outward from the central bit body axis A-A, or in a different position. In some instances, the roller cone axes B-B intersect the central bit body axis A-A, for example, to allow rolling of the roller cones 108 against a rock formation as the example hybrid drill bit 100 rotates about its central bit body axis A-A. Rolling occurs when the roller cone axes B-B intersect the central bit body axis A-A, and a radial vector of the roller cone 108, perpendicular to the roller cone's axis B-B, points in the direction of rotation of the hybrid drill bit 100. In other instances, the roller cone axes B-B do not intersect the central bit body axis A-A, and the roller cone axes B-B are non-radial from the central bit body axis A-A. When a roller cone axis B-B does not intersect the central bit body axis A-A, the roller cone has an additional skidding motion against a formation. In certain instances, a hybrid drill bit can have at least two roller cones, where a first roller cone has a roller cone axis that intersects a central bit body axis, and a second roller cone has a roller cone axis that does not intersect the central bit body axis.
Each of the roller cones 108 includes a cone body 118 and multiple cutting teeth 120 disposed on the cone body 118. In the example shown in
The discs 112 can be provided in a number of positions and configurations. In the example shown, the discs 112 are radially disposed near the outer lateral periphery of the drill end 106. In some instances, the discs 112 are disposed more inward toward the central bit body axis A-A, more outward from the central bit body axis A-A, or in a different position. Each of the discs 112 includes a disc body 122 having multiple disc cutters 126 disposed in a cutting row 124 around the circumference of the disk body 122. The cutting row 124 defines a rotational plane 128 (
In some instances, the disc cutters 126 are a different shape than the cylindrical shape shown in
In the example shown in
In some instances, the bit body 102 includes a nozzle 130 at the drill end 106 to provide drilling fluid to the hybrid drill bit 100 during drilling.
Referring to
In the example shown in
In some instances, the offset distance e is small such that while the hybrid drill bit 100 rotates about the central bit body axis A-A and the drill end 106 is against a formation, the roller cones 108 rotate in a rolling motion with a small amount of shear or skidding relative to rolling. In instances with a small offset distance e, the rolling motion with a small amount of shear or skid facilitates drilling into a formation, for example, in drilling into a soft formation. In other instances, the offset distance e is zero (e.g., as depicted in
The roller cone axis B-B is at a pin angle, βc, relative to a plane perpendicular to the central bit body axis A-A and through the center of the roller cone 108. In the example roller cone 108 shown in
Referring back to
The disc axis C-C is at a pin angle, βd, relative to a plane perpendicular to the central bit body axis A-A and through the center of the disc 112. In the example disc 112 shown in
In certain instances, the roller cones 108 and the discs 112 are symmetrically fixed on the bit body 102 such that the hybrid drill bit 100 is balanced during operation. In other instances, the roller cones 108 and the discs 112 are not symmetrically fixed on the bit body 102.
In the example profile 200 shown in
The outline 202 formed by the disc cutters 126 of the discs 112 can vary.
In some instances, the outline 202 can form a different curve based on the disc axis offset S, disc center offset L, the pin angle βd, and/or another characteristic of the discs 112. In certain instances, roller cone 108 is shaped to substantially match the outline 202 formed by the disc cutters 126. In certain other instances, the outline 202 is shaped to match a shape of the roller cone 108.
Hybrid drill bits, such as the example hybrid drill bit 100, can be configured to rotate about a central bit body axis with a drill end against a formation in a wellbore. Roller cones disposed about the drill end crush or crack a formation in a substantially or wholly rotating action, while disc cutters on a disc scrape against the formation in a shearing action, with the disc configured to rotate. The rotating action of the roller cones includes rolling against the formation, and the shearing action of the discs includes cycling the disc cutters against the formation by rotating the disc. In some instances, the roller cones prefracture the formation such that the disc cutters of the disc scrape the prefractured cuttings of formation.
In instances where the roller cones 108 and discs 112 are symmetrically fixed on the drill end 106 of the bit body 102, symmetry in the roller cones 108 and symmetry in the discs 112 promote a force balance and/or energy balance on the hybrid drill bit 100.
In view of the discussion above, certain aspects encompass, a hybrid drill bit including a bit body defining a central bit body axis, a roller cone at an end of the bit body and rotatably coupled to the bit body about a roller cone axis, and a disc at the end of the bit body and rotatably coupled to the bit body about a disc axis. The roller cone axis extends towards the central bit body axis. The disc axis is transverse to a radial of the central bit body axis through a center of the disc, and the disc includes a plurality of disc cutters.
Certain aspects encompass, a well drilling system including a well head, a drill string connected to the well head, and a hybrid drill bit connected to the drill string. The hybrid drill bit includes a bit body defining a central bit body axis, a roller cone at an end of the bit body and rotatably coupled to the bit body about a roller cone axis, and a disc at the end of the bit body and rotatably coupled to the bit body about a disc axis. The roller cone axis extends toward the central bit body axis, and the disc axis extends away from the central bit body axis.
Certain aspects encompass, a method of cutting a formation in a wellbore. The method includes rotating a drill bit in a formation in a wellbore, crushing or cracking the formation in a rotating action using a roller cone on the drill bit, and scraping the formation in a shearing action using disc cutters on a disc on the drill bit, with the disc configured to rotate.
The aspects above can include some, none, or all of the following features. The hybrid drill bit includes a first arm coupled to the bit body extending generally along the central bit body axis and beyond the end of the bit body and a second arm coupled to the bit body extending generally along the central bit body axis and beyond the end of the bit body. The disc is rotatably coupled to the first arm, and the roller cone is rotatably coupled to the second arm. The roller cone axis intersects the central bit body axis. The roller cone axis is non-radial from the central bit body axis. The shortest distance between the central bit body axis and the roller cone axis is less than 9/16 inches. The roller cone includes a cone body and a plurality of cutting teeth disposed on the cone body. The cutting teeth of the roller cone include milled steel teeth with a hardface metal coating. The plurality of disc cutters on the disc extend further from the end of the bit body than the plurality of cutting teeth on the roller cone. The plurality of cutting teeth on the roller cone extends further from the end of the bit body than the plurality of disc cutters on the disc. The location of the disc is determined by offset distance L and offset distance S. The disc includes a disc body and a generally ring-shaped cutting row radially disposed about the disc body, and the plurality of disc cutters is disposed along the generally ring-shaped cutting row. Each disc cutter in the plurality of disc cutters includes a cylindrical cutter body with a cutter axis through a center of the cylindrical cutter body and a flat cutter face at an end of the cylindrical body. The cutter axis is transverse to a radial from the center of the disc to the center of the cylindrical cutter body. The hybrid drill bit includes a plurality of roller cones and a plurality of discs. Each disc of the plurality of discs has a different disc axis offset, S, and a different disc center offset, L, from the central bit body axis. Each disc axis of the plurality of discs is at a different angle β from the central bit body axis, where the angle β is the angle of the respective rotational axis from the central bit body axis. Crushing or cracking the formation in a rotating action using a roller cone includes prefracturing the formation using the roller cone, and the roller cone is deeper into the formation than the disc cutters of the disc. Scraping the formation in a shearing action using disc cutters on a disc includes scraping prefractured cuttings of formation. Scraping the formation in a shearing action using disc cutters on a disc on the drill but includes rotating the disc about a disc axis such that the disc cutters cycle about the disc axis.
A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be. Accordingly, other embodiments are within the scope of the following claims.
Claims
1. A hybrid drill bit, comprising:
- a bit body defining a central bit body axis;
- a roller cone at an end of the bit body and rotatably coupled to the bit body about a roller cone axis, the roller cone axis extending toward the central bit body axis; and
- a disc at the end of the bit body and rotatably coupled to the bit body about a disc axis; where the disc axis is transverse to a radial of the central bit body axis through a center of the disc; and where the disc comprises a plurality of disc cutters.
2. The hybrid drill bit of claim 1, further comprising:
- a first arm coupled to the bit body extending generally along the central bit body axis and beyond the end of the bit body, where the disc is rotatably coupled to the first arm; and
- a second arm coupled to the bit body extending generally along the central bit body axis and beyond the end of the bit body, where the roller cone is rotatably coupled to the second arm.
3. The hybrid drill bit of claim 1, where the roller cone axis intersects the central bit body axis.
4. The hybrid drill bit of claim 1, where the roller cone axis is non-radial from the central bit body axis.
5. The hybrid drill bit of claim 4, where the shortest distance between the central bit body axis and the roller cone axis is less than 9/16 inches.
6. The hybrid drill bit of claim 1, where the roller cone comprises a cone body and a plurality of cutting teeth disposed on the cone body.
7. The hybrid drill bit of claim 6, where the cutting teeth of the roller cone comprise milled steel teeth with a hardface metal coating.
8. The hybrid drill bit of claim 6, where the plurality of disc cutters on the disc extend further from the end of the bit body than the plurality of cutting teeth on the roller cone.
9. The hybrid drill bit of claim 6, where the plurality of cutting teeth on the roller cone extend further from the end of the bit body than the plurality of disc cutters on the disc.
10. The hybrid drill bit of claim 1, where the disc comprises a disc body and a generally ring-shaped cutting row radially disposed about the disc body; and
- where the plurality of disc cutters are disposed along the generally ring-shaped cutting row.
11. The hybrid drill bit of claim 10, where each disc cutter in the plurality of disc cutters comprises a cylindrical cutter body with a cutter axis through a center of the cylindrical cutter body and a flat cutter face at an end of the cylindrical body; and
- where the cutter axis is transverse to a radial from the center of the disc to the center of the cylindrical cutter body.
12. The hybrid drill bit of claim 1, comprising a plurality of roller cones and a plurality of discs.
13. The hybrid drill bit of claim 12, where each disc of the plurality of discs has a different disc axis offset, S, and a different disc center offset, L, from the central bit body axis; and
- where each disc axis of the plurality of discs is at a different angle β from the central bit body axis, where the angle β is the angle of the respective rotational axis from the central bit body axis.
14. A well drilling system, comprising:
- a well head;
- a drill string connected to the well head;
- a hybrid drill bit connected to the drill string, the hybrid drill bit comprising: a bit body defining a central bit body axis; a roller cone at an end of the bit body and rotatably coupled to the bit body about a roller cone axis, the roller cone axis extending toward the central bit body axis; and a disc at the end of the bit body and rotatably coupled to the bit body about a disc axis, the disc axis extending away from the central bit body axis.
15. The well drilling system of claim 14, where the hybrid drill bit further comprises:
- a first arm coupled to the bit body extending generally along the central bit body axis and beyond the end of the bit body, where the disc is rotatably coupled to the first arm; and
- a second arm coupled to the bit body extending generally along the central bit body axis and beyond the end of the bit body, where the roller cone is rotatably coupled to the second arm.
16. The well drilling system of claim 14, where the roller cone comprises a cone body and a plurality of cutting teeth disposed on the cone body;
- where the disc comprises a disc body and a generally ring-shaped cutting row radially disposed about the disc body; and
- where the generally ring-shaped cutting row includes a plurality of disc cutters disposed along the cutting row.
17. A method of cutting a formation in a wellbore, the method comprising:
- rotating a drill bit in a formation in a wellbore;
- crushing or cracking the formation in a rotating action using a roller cone on the drill bit; and
- scraping the formation in a shearing action using disc cutters on a disc on the drill bit, the disc configured to rotate.
18. The method of claim 17, where crushing or cracking the formation in a rotating action using a roller cone comprises prefracturing the formation using the roller cone, where the roller cone is deeper into the formation than the disc cutters of the disc; and
- where scraping the formation in a shearing action using disc cutters on a disc comprises scraping prefractured cuttings of formation.
19. The method of claim 17, where scraping the formation in a shearing action using disc cutters on a disc on the drill bit further comprises rotating the disc about a disc axis such that the disc cutters cycle about the disc axis.
Type: Application
Filed: Jun 9, 2014
Publication Date: Mar 23, 2017
Inventors: Mark Evans Williams (Conroe, TX), Shilin Chen (Montgomery, TX)
Application Number: 15/309,388