Expandable Bi-Center Drill Bit
A downhole tool for enlarging a borehole, the tool including a body having a central axis, an uphole end, a downhole end, a bore extending from the uphole end, and an aperture extending radially from the bore to a radially outer surface of the body. Additionally, the tool includes a mandrel disposed in the bore, the mandrel having a first end, a second end, a radially outer surface, and a radially inner surface. The mandrel outer surface includes an inclined surface. Further, the tool includes a first blade disposed in the aperture. The first blade has a radially retracted position and a radially extended position configured to engage with a borehole sidewall to enlarge the borehole. The mandrel is configured to translate axially relative to the body to slide the inclined surface along the first blade to transition the first blade between the radially refracted and extended positions.
This application claims benefit of U.S. provisional patent application Ser. No. 61/982,028 filed Apr. 21, 2014, and entitled “Expandable Bi-Center Drill Bit,” which is hereby incorporated herein by reference in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTNot applicable.
BACKGROUNDEmbodiments described herein relate generally to earth-boring drill bits used to drill a borehole for the ultimate recovery of oil, gas, or minerals. More particularly, embodiments described herein relate to expandable drill bits and actuation systems for such bits.
In drilling a borehole (or wellbore) into the earth for the recovery of hydrocarbons from a subsurface formation, it is conventional practice to connect a drill bit to the lower end of a conduit (e.g., drill string, coiled tubing, etc.). The drill bit is then rotated either alone or along with the conduit with weight on bit (WOB) applied to engage the earthen formation and thus lengthen the resulting borehole. As the borehole extends deeper within the subterranean formation, casing pipe is inserted therein to line and thus provide additional structural reinforcement for borehole.
Often it is desirable to drill a slightly larger diameter borehole within the producing zones of the formation than in the initial sections of borehole that are closer to the surface. However, a larger bit may not be capable of passing through the relatively smaller casing string and borehole to reach the desired zone for larger borehole drilling. Eccentric drill bits and other cutting structures have been developed that are capable of drilling a relatively large borehole when rotated about their center of rotation, while maintaining a sufficiently small pass-through diameter capable of being advanced through the relatively smaller casing string. However, these bits are typically limited to a single size such that drilling selectively larger and smaller boreholes is not possible with a given bit, and unfortunately, replacing a drill bit with a different sized drill bit (to form a smaller or larger section of the borehole) often requires bringing the drill bit, along with the entire length of drillstring to the surface. This action is typically referred to as a “trip” of the drill bit and drillstring and requires hours of additional personnel and equipment time, such that each trip to the surface dramatically increases the total costs of drilling the borehole.
BRIEF SUMMARY OF THE DISCLOSUREEmbodiments disclosed herein are directed to a drill bit for drilling a borehole in a subterranean formation. In an embodiment, the drill bit includes a bit body having a central axis, an uphole end configured to be coupled to a drill string, and a downhole end including a cutting structure configured to engage the formation, wherein the bit body includes a bore extending axially from the uphole end and an aperture extending radially from the bore to a radially outer surface of the bit body. In addition, the drill bit includes a mandrel movably disposed in the bore, wherein the mandrel has a first end, a second end, a radially outer surface extending axially from the first end to the second end, and a radially inner surface extending axially from the first end to the second end. The outer surface of the mandrel includes an inclined surface oriented at an acute angle relative to the central axis. Further, the drill bit includes a first blade moveably disposed in the aperture and axially positioned between the cutting structure and the uphole end. The first blade has a radially retracted position and a radially extended position configured to engage a sidewall of the borehole to enlarge the borehole. The mandrel is configured to translate axially relative to the bit body to slide the inclined surface of the mandrel along the first blade to transition the first blade between the radially refracted position and the radially extended position.
Embodiments disclosed herein are directed to a downhole tool for enlarging a borehole extending through a subterranean formation. In an embodiment, the downhole tool has a central axis and includes a body having a central axis, an uphole end configured to be coupled to a drill string, a downhole end, a bore extending axially from the uphole end, and an aperture extending radially from the bore to a radially outer surface of the body. In addition, the downhole tool includes a mandrel movably disposed in the bore, wherein the mandrel has a first end, a second end, a radially outer surface extending axially from the first end to the second end, and a radially inner surface extending axially from the first end to the second end. The outer surface of the mandrel includes an inclined surface oriented at an acute angle relative to the central axis. Further, the downhole tool includes a first blade movably disposed in the aperture, wherein the first blade has a radially refracted position and a radially extended position configured to engage with a sidewall of the borehole to enlarge the borehole. The mandrel is configured to translate axially relative to the body to slide the inclined surface of the mandrel along the first blade to transition the first blade between the radially refracted position and the radially extended position.
Embodiments disclosed herein are directed to a method for enlarging a borehole extending through a subterranean formation. In an embodiment, the method includes (a) rotating a downhole tool about a central axis, the downhole tool including a central bore and a blade. In addition, the method includes (b) flowing drilling fluid through the bore of the downhole tool, wherein the drilling fluid has a pressure in the bore. Further, the method includes (c) increasing the pressure of the drilling fluid in the bore, and (d) moving a mandrel axially within the bore in a first direction in response to the increase in pressure in (c). Still further, the method includes (e) slidingly engaging the blade with an inclined surface on the mandrel during (d), and (f) moving the blade radially outward in response to the sliding engagement in (e).
Embodiments described herein comprise a combination of features and advantages intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical advantages of the invention in order that the detailed description of the invention that follows may be better understood. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:
The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.
Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.
In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . . ” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis. Any reference to up or down in the description and the claims is made for purposes of clarity, with “up”, “upper”, “upwardly”, “uphole”, or “upstream” meaning toward the surface of the borehole and with “down”, “lower”, “downwardly”, “downhole”, or “downstream” meaning toward the terminal end of the borehole, regardless of the borehole orientation. As used herein, the term “Bi-center bit” is used to refer to a drill bit or other cutting tool that is configured to simultaneously drill a borehole having an initial diameter and enlarge the borehole to a final diameter that is larger than the initial diameter.
Referring now to
Drilling system 10 also includes a drill string 30, a bottom hole assembly 32, and a drill bit 100. Drill string 30 has a central or longitudinal axis 35, a first or uphole end 30a, and a second or downhole end 30b. In this embodiment, drill string 30 is made from a plurality of tubulars or pipe joints 31 coupled together end-to-end. Each pipe joint 31 has a first or upper end 31a comprising an internally threaded box and a second or lower end 31b comprising an externally threaded pin. Joints 31 are connected end-to-end by threading pins into the mating boxes to form threaded connections or joints 34. Bottom hole assembly (BHA) 32 is coupled to the lower end 30b of drill string 30 and drill bit 100 is coupled to the lower end of BHA 32.
During drilling operations, drill bit 100 is rotated with weight-on-bit (WOB) applied to drill the borehole 11 through the formation 12. Traveling block 22 is operated to control the WOB, which impacts the rate-of-penetration of drill bit 100 through the formation 12. In this embodiment, drill bit 100 can be rotated from the surface by drillstring 30 via top drive 23, rotated by downhole mud motor 33 disposed in BHA 32 proximal bit 100, or combinations thereof (e.g., rotated by both drillstring 30 and mud motor 33). In either case, the rate-of-penetration (ROP) of the drill bit 100 into the borehole 11 for a given formation and a drilling assembly largely depends upon the WOB and the rotational speed of bit 100. During drilling operations a mud system 40 circulates pressurized drilling fluid or mud 41 down the drill string 30, through nozzles in the face of bit 100, and back up the annulus 42 between the drill string 30 and sidewall 11a of borehole 11.
As drill bit 100 and drill string 30 penetrate deeper into formation 12, casing 60 is installed within borehole 11 to ensure the structural integrity thereof as well as to limit/prevent fluid communication between formation 12 and borehole 11. Casing 60 includes an inner diameter D60 which defines the maximum outer diameter for any tool (e.g., bit 100) passing through wellbore 11. However, for some operations, it may become desirable to drill a larger diameter section of borehole 11 below casing 60 (i.e., to a diameter larger than inner diameter D60). As previously described, tripping the drill bit 100 to the surface to install a different bit (e.g., an eccentric bit capable of passing through casing 60 and drilling the larger diameter borehole) is generally undesirable. Thus, embodiments disclosed herein include downhole tools such as, for example, a drill bit (e.g., drill bit 100) that include a radially extendable member capable of selective radial retraction/extension to enable passage through the casing 60 as well as drilling selectively large or small sections of borehole 11 without needing to trip the bit to the surface.
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In this embodiment, radially outer end 160a includes a pair of circumferentially-spaced parallel blades 166 configured to engage formation 12 during drilling operations to radially enlarge borehole 11 to a desired diameter greater than that formed by cutting structure 150. Each blade 166 includes a formation facing surface 168 and a plurality of cutter elements 152 as previously described mounted to surface 168. When bit 100 is rotated about axis 105 in cutting direction 153, cutter elements 152 on member 160 may engage with and shear off portions of sidewall 11a of borehole 11.
Referring now to
Referring now to
During operations, cutting member 160 may be transitioned between a first or radially retracted position, such as shown in
When it becomes desirable to transition member 160 of bit 100 to the radially expanded position (e.g.,
When it becomes desirable to transition member 160 of bit 100 back to the radially retracted position (e.g.,
In this embodiment, with member 160 in the radially retracted position (e.g.,
Further, with member 160 in the radially retracted position (e.g.,
In the manner described, a drill bit (or other downhole tool) in accordance with the principles disclosed herein (e.g., drill bit 100) may be disposed on a downhole end of a drill string (e.g., drill string 30) and selectively radially retracted so that the bit may be passed through a relatively narrow casing (e.g., casing 60) and selectively radially expanded to allow the bit to form a borehole having a diameter that is larger than the inner diameter of the casing. In addition, through use of a drill bit in accordance with the principles disclosed herein (e.g., bit 100), selectively smaller/larger diameter boreholes (e.g., borehole 11) may be formed without needing to trip the bit and drill string to the surface. Still further, because member 160 is incorporated within a relatively small downhole tool (e.g., bit 100), the utilization of drill bits and/or downhole tools in accordance with the principles disclosed herein may be more easily utilized in directional drilling applications.
While embodiments disclosed herein have included a drill bit 100, it should be appreciated that the principles disclosed herein may be utilized on other downhole tools. For example, referring now to
While embodiments disclosed herein have shown drill bit 100 coupled to downhole end 30b of drill string 30, it should be appreciated that in other embodiments, drill bit 100 may be coupled to any suitable conduit for suspending a drilling bit within a subterranean wellbore during drilling operations, such as, for example, coiled tubing. In addition, while embodiments disclosed herein have included a plurality of fixed members 162 on bit 100, it should be appreciated that in other embodiments no fixed members 162 are included or only a single member 162 is included on bit 100 while still complying with the principles disclosed herein. Also, in some embodiments, each of the fixed members 162 may have the same or different heights H162.
While preferred embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the invention. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.
Claims
1. A drill bit for drilling a borehole in a subterranean formation, the drill bit comprising:
- a bit body having a central axis, an uphole end configured to be coupled to a drill string, and a downhole end including a cutting structure configured to engage the formation, wherein the bit body includes a bore extending axially from the uphole end and an aperture extending radially from the bore to a radially outer surface of the bit body;
- a mandrel movably disposed in the bore, wherein the mandrel has a first end, a second end, a radially outer surface extending axially from the first end to the second end, and a radially inner surface extending axially from the first end to the second end, wherein the outer surface of the mandrel includes an inclined surface oriented at an acute angle relative to the central axis; and
- a first blade moveably disposed in the aperture and axially positioned between the cutting structure and the uphole end, wherein the first blade has a radially retracted position and a radially extended position configured to engage a sidewall of the borehole to enlarge the borehole;
- wherein the mandrel is configured to translate axially relative to the bit body to slide the inclined surface of the mandrel along the first blade to transition the first blade between the radially retracted position and the radially extended position.
2. The drill bit of claim 1, further comprising a biasing member engaging the mandrel and configured to bias the mandrel axially toward the downhole end.
3. The drill bit of claim 2, wherein the biasing member is coiled spring axially compressed between the first end of the mandrel and an inner shoulder of a connection sub coupled to the uphole end of the bit body.
4. The drill bit of claim 2, wherein the first end of the mandrel comprises a first end face and the second end of the mandrel comprises a second end face, wherein the first end face has a first surface area and the second end face has a second surface area that is greater than the first surface area.
5. The drill bit of claim 1, wherein the inner surface of the mandrel defines a central throughbore configured to flow drilling fluids therethrough.
6. The drill bit of claim 1, wherein the first blade has a radially inner end comprising a recess including an inclined surface oriented at an acute angle β relative to the central axis and configured to slidingly engage the inclined surface of the mandrel.
7. The drill bit of claim 1, wherein the inclined surface on the mandrel is an annular frustoconical surface.
8. The drill bit of claim 1, wherein the axial translation of the mandrel toward the uphole end of the bit body is configured to transition the first blade to the radially extended position and axial translation of the mandrel away from the uphole end of the bit body is configured to transition the first blade to the radially retracted position.
9. The drill bit of claim 1, wherein the first blade includes a plurality of cutter elements configured to engage the sidewall of the borehole to enlarge the borehole.
10. The drill bit of claim 1, further comprising a fixed second blade extending radially outward from the radially outer surface of the bit body and configured to engage the sidewall of the borehole to enlarge the borehole, wherein the first blade extends radially outward beyond the second blade when the first blade is in the radially extended position.
11. A downhole tool for enlarging a borehole extending through a subterranean formation, the downhole tool having a central axis and comprising:
- a body having a central axis, an uphole end configured to be coupled to a drill string, a downhole end, a bore extending axially from the uphole end, and an aperture extending radially from the bore to a radially outer surface of the body;
- a mandrel movably disposed in the bore, wherein the mandrel has a first end, a second end, a radially outer surface extending axially from the first end to the second end, and a radially inner surface extending axially from the first end to the second end, wherein the outer surface of the mandrel includes an inclined surface oriented at an acute angle relative to the central axis; and
- a first blade movably disposed in the aperture, wherein the first blade has a radially refracted position and a radially extended position configured to engage with a sidewall of the borehole to enlarge the borehole;
- wherein the mandrel is configured to translate axially relative to the body to slide the inclined surface of the mandrel along the first blade to transition the first blade between the radially retracted position and the radially extended position.
12. The downhole tool of claim 11, further comprising a biasing member engaging the mandrel and configured to bias the mandrel axially toward the downhole end.
13. The downhole tool of claim 12, wherein the biasing member is coiled spring axially compressed between the first end of the mandrel and an inner shoulder of a connection sub coupled of the uphole end of the body.
14. The downhole tool of claim 11, wherein the first end of the mandrel comprises a first end face and the second end of the mandrel comprises a second end face, wherein the first end face has a first surface area and the second end face has a second surface area that is greater than the first surface area.
15. The downhole tool of claim 11, wherein the inner surface of the mandrel defines a central throughbore configured to flow drilling fluids therethrough.
16. The downhole tool of claim 11, wherein the first blade has a radially inner end comprising a recess including an inclined surface oriented at an acute angle relative to the central axis and configured to slidingly engage the inclined surface of the mandrel.
17. The downhole tool of claim 11, wherein the inclined surface on the mandrel is an annular frustoconical surface.
18. The downhole tool of claim 11, wherein axial translation of the mandrel toward the uphole end of body is configured to transition the first blade to the radially extended position and axial translation of the mandrel away from the uphole end of the body is configured to transition the first blade to the radially refracted position.
19. The downhole tool of claim 11, wherein the first blade includes a plurality of cutter elements configured to engage the sidewall of the borehole to enlarge the borehole.
20. The downhole tool of claim 11, further comprising a fixed second blade extending radially outward from the radially outer surface of the bit body and configured to engage the sidewall of the borehole to enlarge the borehole, wherein the first blade extends radially outward beyond the second blade when the first blade is in the radially extended position.
21. A method for enlarging a borehole extending through a subterranean formation, the method comprising:
- (a) rotating a downhole tool about a central axis, the downhole tool including a central bore and a blade;
- (b) flowing drilling fluid through the bore of the downhole tool, wherein the drilling fluid has a pressure in the bore;
- (c) increasing the pressure of the drilling fluid in the bore;
- (d) moving a mandrel axially within the bore in a first direction in response to the increase in pressure in (c);
- (e) slidingly engaging the blade with an inclined surface on the mandrel during (d); and
- (f) moving the blade radially outward in response to the sliding engagement in (e).
22. The method of claim 21, further comprising:
- (g) axially biasing the mandrel in a second direction opposite the first direction with a biasing force; and
- (h) overcoming the biasing force with a force applied to the mandrel by the drilling fluid during (c).
23. The method of claim 21, wherein the inclined surface on the mandrel is a frustoconical surface and the blade includes a frustoconical surface;
- wherein (e) comprises slidingly engaging the frustoconical surface of the mandrel with the frustoconical surface of the blade.
24. The method of 21, further comprising:
- (g) decreasing the pressure of the drilling fluid in the bore after (f);
- (h) moving the mandrel axially within the central flow passage in a second direction opposite the first direction in response to (g); and
- (i) moving the blade radially inward in response to (h).
Type: Application
Filed: Apr 17, 2015
Publication Date: Oct 22, 2015
Inventors: Carl William Diller (Las Vegas, NV), Candice English (Anchorage, AK), Robert D. Harris (Willow, AK), John Robert Milne (Anchorage, AK), Matthew Ora Ross (Eagle River, AK)
Application Number: 14/689,940