SYSTEMS AND METHODS FOR RUNNING TUBULARS INTO SUBTERRANEAN WELLBORES

Abstract

A guide assembly for running a liner through a borehole extending through a subterranean formation, the guide assembly having a central axis, a first end configured to be coupled to the liner, and a second end opposite the first end. The guide assembly includes a guide shoe disposed at the second end, a drive assembly including a radially outer housing, and a rotor concentrically disposed in the housing. The rotor has a first end distal the guide shoe and a second end fixably coupled to the guide shoe, and is configured to rotate about the central axis relative to the housing about the central axis.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent application Ser. No. 61/971,400 filed Mar. 27, 2014, and entitled “Systems and Methods for Running Tubulars into Subterranean Wellbores,” which is hereby incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND

Embodiments described herein relate generally to systems and methods for accessing and producing hydrocarbons from a subterranean formation. More particularly, the invention relates to systems and methods for lining subterranean boreholes.

In drilling operations, a large diameter hole is drilled from the surface to a selected depth. Then, a primary conductor secured to the lower end of an outer wellhead housing disposed at the surface, also referred to as a low pressure housing, is run into the borehole. Cement is pumped down the primary conductor and allowed to flow back up the annulus between the primary conductor and the borehole sidewall.

With the primary conductor secured in place, a drill bit is lowered through the primary conductor to drill the borehole to a second depth. Next, an inner wellhead housing, also referred to as a high pressure housing, is seated in the upper end of the outer wellhead housing. A string of casing secured to the lower end of the inner wellhead housing or seated in the inner wellhead housing extends downward through the primary conductor. Cement is pumped down the casing string, and allowed to flow back up the annulus between the casing string and the primary conductor and out cement ports extending radially through the outer wellhead housing. The drill bit is lowered through the primary conductor and the casing string and drilling continues.

To ensure well integrity, the open borehole extending from the primary conductor and casing string is lined with a tubular liner, which can be in the form of successive casing strings, coiled tubing, or the like. Following drilling, the liner is typically run from the surface through the primary conductor, any previously installed casing, and the open borehole to the desired depth, and then cemented in place. While running the liner through the open borehole, the liner may get hung up or stuck on cutting debris, a ledge, or other obstruction that interferes with the advancement of the liner. A stuck liner may require remedial actions, result in delays, and added costs. A guide shoe may be provided at the lower end of the liner to facilitate its advancement through the open borehole and around obstructions. However, conventional guide shoes exhibit varying degrees of success, and further, some conventional guide shoes do not allow for cementing without an additional tripping operation.

BRIEF SUMMARY OF THE DISCLOSURE

These and other needs in the art are addressed in one embodiment by a guide assembly for running a liner through a borehole extending through a subterranean formation. The guide assembly has a central axis, a first end configured to be coupled to the liner, and a second end opposite the first end. In an embodiment, the guide assembly includes a guide shoe disposed at the second end, a drive assembly including a radially outer housing, and a rotor concentrically disposed in the housing. In addition, the rotor is configured to rotate about the central axis relative to the housing about the central axis. Further, the rotor has a first end distal the guide shoe and a second end fixably coupled to the guide shoe.

These and other needs in the art are addressed in one embodiment by a guide assembly for running a liner through a borehole extending through a subterranean formation. The guide assembly has a central axis, a first end configured to be coupled to the tubular, and a second end opposite the first end. In an embodiment, the guide assembly includes a guide shoe disposed at the second end and a drive assembly including a radially outer housing and a rotor rotatably disposed in the housing. In addition, the rotor has a first end distal the guide shoe, a second end fixably coupled to the guide shoe, and an outer surface extending from the first end of the rotor to the second end of the rotor, wherein the outer surface of the rotor includes a plurality of circumferentially-spaced parallel helical flights. Further, the assembly includes an inlet guide disposed about the rotor and axially positioned between the first end of the rotor and the plurality of helical flights of the rotor, wherein the inlet guide has an outer surface including a plurality of circumferentially-spaced parallel helical flights. Moreover, each of the helical flights of the rotor spiral about the central axis in a first direction and the plurality of helical flights of the inlet guide spiral about the central axis in a second direction that is opposite the first direction.

These and other needs in the art are addressed in one embodiment by a guide assembly for running a tubular through a borehole extending through a formation. The guide assembly having a central axis, a first end configured to be coupled to the tubular, and a second end opposite the first end. In an embodiment, the guide assembly includes a guide shoe disposed at the second end and a drive assembly configured to drive the rotation of the guide shoe about the central axis. In addition, the drive assembly includes a radially outer tubular housing and a rotor rotatably disposed within the housing. Further, the rotor has a first end distal the guide shoe and a second end fixably coupled to the guide shoe, and includes a bore extending axially from the second end of the rotor and a port extending radially from an outer surface of the rotor to the bore. Moreover, the guide shoe includes an inner fluid cavity in fluid communication with the bore of the rotor and a port extending from the inner fluid cavity to an outer surface of the guide shoe.

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.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the disclosure, reference will now be made to the accompanying drawings in which:

FIG. 1 is a schematic view of a wellbore and an embodiment of a system in accordance with the principles described herein for running a liner in the wellbore;

FIG. 2 is a perspective view of the guide assembly of FIG. 1;

FIG. 3 is a perspective cross sectional view of the guide assembly of FIG. 2;

FIG. 4 is a cross sectional side view of the connection sub of FIG. 2;

FIG. 5 is a partial cut away side view of the drive assembly of FIG. 2;

FIG. 6 is a partial cut away perspective view of the outer housing of FIG. 2;

FIG. 7 is a cross sectional side view of the outer housing of FIG. 2;

FIG. 8 is side view of a rotor of the drive assembly of FIG. 5;

FIG. 9 is a cross sectional side view of the rotor of FIG. 8;

FIG. 10 is a cross sectional end view of the rotor of FIG. 8;

FIG. 11 is a side view of the inlet guide of the drive assembly of FIG. 5;

FIG. 12 is a cross-sectional side view of the inlet guide of FIG. 11;

FIG. 13 is a partial cut away perspective view of the inlet guide of FIG. 11;

FIG. 14 is a partial cut away end view of the inlet guide of FIG. 11;

FIG. 15 is an enlarged partial cut away side view of the upper end of the guide assembly of FIG. 2;

FIG. 16 is an enlarged partial cut away side view of the lower end of the guide assembly of FIG. 2;

FIG. 17 is a side view of the guide shoe of FIG. 2;

FIG. 18 is a cross-sectional side view of the guide shoe of FIG. 17; and

FIGS. 19A-19D illustrate schematic side views of alternative embodiments of guide shoes for use with the guide assembly of FIG. 2.

DETAILED DESCRIPTION

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 disclosures, including the claims, is limited to that embodiment.

Certain terms are used throughout the following description and claims to refer to particular system components. This document does not intend to distinguish between components that differ in name but not function. Moreover, the drawing figures are not necessarily to scale. Certain features of the disclosure may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. Further, some drawing figures may depict vessels in either a horizontal or vertical orientation; unless otherwise noted, such orientations are for illustrative purposes only and is not a required aspect of this disclosure.

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 terms “couple,” “attach,” “connect” or the like are intended to mean either an indirect or direct mechanical or fluid connection, or an indirect, direct, optical or wireless electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct mechanical or electrical connection, through an indirect mechanical or electrical connection via other devices and connections, through an optical electrical connection, or through a wireless electrical connection. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a given axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the axis. For instance, an axial distance refers to a distance measured along or parallel to the axis, and a radial distance means a distance measured perpendicular to the axis. Any reference to up or down in the description and the claims will be made for purpose of clarification, with “up,” “upper,” “upwardly,” or “upstream” meaning toward the surface of the well and with “down,” “lower,” “downwardly,” or “downstream” meaning toward the terminal end of the well, regardless of the well bore orientation. In some applications of the technology, the orientations of the components with respect to the surroundings may be different. For example, components described as facing “up,” in another application, may face to the left, may face down, or may face in another direction.

Referring now to FIG. 1, an embodiment of a system 10 for running and advancing a liner 50 through a borehole 20 is shown. Borehole 20 extends from the surface 30 through a subterranean formation 31. The upper portion of borehole 20 is lined with a primary conductor 21 extending downward from a wellhead 22 at the surface 30 and a casing string 23 extending from wellhead 22 through primary conductor 21. Casing 23 and conductor 21 are cemented in place. However, the portion of borehole downhole of casing 23 is open (i.e., it is not cased or lined). Accordingly, system 10 runs liner 50 from the surface through conductor 21, casing 23, and borehole 20 to line the open portion of borehole 20 disposed downhole of casing 23. In general, liner 50 can be any tubular known in the art including, without limitation, coiled tubing, casing or casing string, drill pipe, or the like. Thus, as used herein, the term “liner” is used to refer to any elongate tubular including, without limitation, coiled tubing, casing, drill pipe, pipe string, casing string, production tubing, or the like.

In this embodiment, system 10 includes a power source 11, a surface processor 12, a liner reel or spool 13, an injector head unit 14, liner 50, and a shoe or guide assembly 100. Power source 11, processor 12, spool 13, and injector head unit 14 are disposed at the surface 30. Power source 11 provides electrical power to system 10 and processor 12 controls the operation of system 10. Spool 13 stores liner 50 and pays out liner 50 as it is fed by injector head unit 14 through wellhead 20, conductor 21, and casing 23 into the open portion of borehole 20. Guide assembly 100 is mounted to the lower end of liner 50 and facilitates the advancement of liner 50 through conductor 21, and casing 23, and the open portion of borehole 20. An annulus 24 is formed between liner 50 and the open portion of borehole 20. Annulus 24 extends to the surface 30 and is at least partially filled with cement to secure liner 50 in place once it is disposed at the desired depth in borehole 20. As will be described in more detail below, guide assembly 100 allows the cementing of liner 50 without having to trip liner 50 or guide assembly 100.

As shown in FIG. 1, liner 50 is jointed pipe that is then deployed by coiled tubing paid out from coiled tubing reel 13. Further, although guide assembly 100 is shown and described as running liner 50 through the open portion of borehole 20, in general, guide assembly 100 can be employed to facilitate the run in of any downhole device or tubular through an open portion of a borehole, a cased wellbore, another tubular, or combinations thereof.

Referring now to FIGS. 2 and 3, guide assembly 100 has a central or longitudinal axis 105, a first or upper end 100a coupled to the lower end of liner 50, and a second or lower end 100b distal liner 50. Thus, as liner 50 and guide assembly 100 advance through wellbore 20, end 100b leads. In this embodiment, guide assembly 100 includes a connection sub 110 at upper end 100a, a guide shoe 180 at lower end 100b, and a drive assembly 120 axially positioned between sub 110 and guide shoe 180. As will be described in more detail below, connection sub 110 connects guide assembly 100 to liner 50 and drive assembly 120 powers the rotation of guide shoe 180.

Referring now to FIGS. 2-4, connection sub 110 is a tubular sub that connects drive assembly 120 to lower end of liner 50. Sub 110 has a central axis coaxially aligned with axis 105, a first or upper end 110a coincident with end 100a, a second or lower end 110b coupled to drive assembly 120, a radially outer cylindrical surface 111 extending axially between ends 110a, 110b, and a radially inner surface 112 extending axially between ends 110a, 110b. In this embodiment, upper end 110a comprises an internally threaded box end (internal threads not shown) that threadably connects sub 110 to a mating pin end at the lower end of liner 50.

Inner surface 112 of connection sub 110 includes a first cylindrical section 112a extending axially from end 110a to a downward-facing annular planar shoulder 113a, a second cylindrical section 112b extending axially from shoulder 113a to a frustoconical annular shoulder 113b, and an internal threaded section 112c extending axially from shoulder 113b to end 110b. First cylindrical section 112a is disposed at a diameter that is less than the diameter of second cylindrical section 112b. As will be described in more detail below, internally threaded section 112c defines a box end that threadably connects connection sub 110 to a mating pin end of drive assembly 120.

Referring now to FIGS. 3 and 5, drive assembly 120 has a first or upper end 120a coupled to connection sub 110 and a second or lower end 120b coupled to guide shoe 180. In this embodiment, drive assembly 120 includes a radially outer housing 121, a rotor 130 rotatably disposed within housing 121, an inlet guide 140 disposed about rotor 130 within housing 121, and a retention cap 175. Housing 121, rotor 130, and inlet guide 140 each has a central axis coaxially aligned with axis 105. An annular washer or spacer 170 is disposed about rotor 130 and axially compressed between retainer cap 175 and first bearing assembly 150.

Referring now to FIGS. 5-7, outer housing 121 is a tubular having a first or upper end 121a threadably attached to lower end 110b of connection sub 110, a second or lower end 121b axially adjacent guide shoe 180, a radially outer surface 122 extending axially between ends 121a, 121b, and a radially inner surface 125 extending axially between ends 121a, 121b. Outer surface 122 includes an externally threaded section 123a at upper end 121a, an upward-facing planar annular shoulder 123b axially adjacent section 121a, a downward-facing planar annular shoulder 123c at lower end 121b, and a cylindrical section 123d extending axially between shoulders 123b, 123c. Externally threaded section 123a defines a pin end that threadably engages mating internally threaded section 112c of connection sub 110, thereby connecting housing 121 to sub 110.

As best shown in FIGS. 6 and 7, inner surface 125 includes a first cylindrical section 126a extending axially from end 121a to an upward-facing annular frustoconical shoulder 126b, a second cylindrical section 126c extending axially from shoulder 126b to a downward-facing planar annular shoulder 126d, and a third cylindrical section 126e extending axially from shoulder 126d to end 121b. Second cylindrical section 126c is disposed at a diameter that is less than the diameter of first cylindrical section 126a and third cylindrical section 126e. Thus, shoulders 126b, 126d extend radially inward from sections 126a, 126e, respectively, to section 126c.

In this embodiment, outer housing 121 is formed by multiple tubular members coupled together end-to-end. However, in general, the outer housing (e.g., outer housing 121) can be formed as a monolithic tubular or by coupling any number of tubular members together.

Referring now to FIGS. 3, 8, and 9, rotor 130 is an elongate member having a first or upper end 130a, a second or lower end 130b, and a radially outer surface 131 extending axially between ends 130a, 130b. As best shown in FIGS. 8 and 9, and moving axially from end 130a to end 130b, outer surface 131 includes an externally threaded section 131a at end 130a, an annular recess 131b axially adjacent threaded section 131a, a first cylindrical section 131c, an upward-facing annular planar shoulder 132a, a flighted section 135, a second cylindrical section 131d, an upward-facing annular frustoconical shoulder 132b, a third cylindrical section 131e, an annular recess 131f, and an externally threaded section 131g at end 130b. Threaded section 131a is threadably attached to retention cap 175, first cylindrical section 131c extends axially from annular recess 131b to shoulder 132a, flighted section 135 extends axially between shoulder 132a and second cylindrical section 131d, shoulder 132b is axially positioned between cylindrical sections 131d, 131e, third cylindrical section 131e extends axially from shoulder 132b to annular recess 131f, and externally threaded section 131g is threadably attached to guide shoe 180.

Referring now to FIGS. 8-10, flighted section 135 of outer surface 131 includes a plurality of circumferentially-spaced parallel flights 136 that extend helically about axis 105 and axially between shoulder 132a and section 131d. In this embodiment, rotor 130 includes three uniformly circumferentially-spaced flights 136. Thus, flights 136 are uniformly angularly spaced 120° apart about axis 105. However, in general, the rotor (e.g., rotor 130) can include any suitable number of flights (e.g., two, three, four, or more flights 136), and further, the circumferential spacing of the flights can be uniform or non-uniform.

Each flight 136 has a first or upper end 136a, a second or lower end 136b, lateral sides 137a, 137b extending between ends 136a, 136b, a radially inner base 138a integral with the remainder of rotor 130 and extending between ends 136a, 136b, and a radially outer generally cylindrical surface 138b distal the remainder of rotor 130 and extending between ends 136a, 136b. In this embodiment, each flight 136 has the same length measured between ends 136a, 136b. Radially outer surface 138b of each flight 136 is disposed at a uniform radius R_138b, and each flight 136 has a height H₁₃₆ measured radially from its base 138a to its outer surface 138b. In this embodiment, outer surfaces 138b of flights 136 do not engage housing 121, and thus, radius R_138b is less than the inner radius of housing 121 along cylindrical section 126a. In general, the radius R_138b of each outer surface 138b is preferably between 1/16 and 2.0 in., and each height H₁₃₆ is preferably between 1/16 and 2.0 in. In this embodiment, radius R_138b of each outer surface 138b is the same, and in particular, is ¼ in.; and each height H₁₃₆ of each flight 136 is the same, and in particular, is ⅜ in. In addition, each flight 136 is oriented at an acute flight angle θ₁₃₆ relative to a reference plane A perpendicular to axis 105 in side view, and has a pitch P₁₃₆ equal to the axial length (center-to-center) of one complete turn of flight 136. Flight angle θ₁₃₆ of each flight 136 is preferably between 0° and 90°, and more preferably between 30° and 60°. Pitch P₁₃₆ of each flight 136 is preferably between ½ and 5 revolutions over 12.0 in., and more preferably between 1 and 2 revolutions over 12.0 in. In this embodiment, flights 136 are identical and parallel, and thus, radius R_138b of each outer surface 138b is the same, flight angle θ₁₃₆ of each flight 136 is the same and pitch P₁₃₆ of each flight 136 is the same. In particular, in this embodiment, flight angle θ₁₃₆ of each flight 136 is 45° and pitch P₁₃₆ of each flight 136 is 1¼ revolutions over 12.0 in. As best shown in FIG. 10, when the rotor 130 is viewed from above along axis 105, flights 136 spiral in a counterclockwise direction.

In this embodiment, flighted section 135 of outer surface 131 also includes a plurality of circumferentially adjacent parallel grooves 139 disposed between each pair of circumferentially adjacent flights 136. Grooves 139 offer the potential to facilitate and assist fluid flow through drive assembly 120.

As best shown in FIGS. 8 and 9, rotor 130 includes a bore 133 extending axially from lower end 130b and a plurality of uniformly circumferentially-spaced ports 134 extending radially from cylindrical section 131b of outer surface 131 to bore 133. In this embodiment, ports 134 are generally elliptically shaped and angularly spaced 180° apart about axis 105.

Referring now to FIGS. 5 and 11-14, inlet guide 140 is disposed about rotor 130 within connection sub 110 and seated against upper end 121a of housing 121. In addition, inlet guide 140 has a first or upper end 140a, a second or lower end 140b axially abutting housing 121, a radially inner surface 141 extending axially between ends 140a, 140b, and a radially outer surface 145 extending axially between ends 140a, 140b. Inner surface 141 of inlet guide 140 includes a first cylindrical section 142a extending axially from upper end 140a to an upward-facing annular planar shoulder 142b and a second cylindrical section 142c extending axially from lower end 140b to shoulder 142b. Cylindrical section 142a is disposed at a diameter that is greater than the diameter of cylindrical section 142c.

Outer surface 145 of inlet guide 140 includes a plurality of uniformly circumferentially-spaced parallel flights 146 that extend helically about axis 105 and axially between ends 140a, 140b. In this embodiment, inlet guide 140 includes three uniformly circumferentially-spaced flights 146. Thus, flights 146 are angularly spaced 120° apart about axis 105. However, in general, the inlet guide (e.g., inlet guide 140) can include any suitable number of flights (e.g., two, three, four, or more flights 146), and further, the flights can be uniformly or non-uniformly circumferentially-spaced. Each flight 146 has a radially inner base 147a integral with the remainder of inlet guide 140 and a radially outer generally cylindrical surface 147b distal the remainder of inlet guide 140. Surface 147b of each flight 146 is disposed at a uniform radius R_147b, and each flight 146 has a height H₁₄₆ measured radially from its base 147a to its outer surface 147b. Surfaces 147b of flights 146 statically engage second cylindrical section 112b of connection sub 110, and thus, radius R_147b of each radially outer surface 147b is substantially the same as the inner radius of connection sub 110 along second cylindrical section 112b. In general, the radius R₁₄₇b of each outer surface 147b is preferably between 1/16 and 2.0 in., and each height H₁₄₆ is preferably between 1/16 and 2.0 in. In this embodiment, radius R_147b of each outer surface 147b is the same, and in particular, is ¼ in.; and each height H₁₄₆ of each flight 146 is the same, and in particular, is ⅜ in. In addition, each flight 146 is oriented at an acute flight angle θ₁₄₆ relative to a reference plane A perpendicular to axis 105 in side view, and has a pitch P₁₄₆ equal to the axial length (center-to-center) of one complete turn of flight 146. Flight angle θ₁₄₆ of each flight 146 is preferably between 0° and 90°, and more preferably between 30° and 60°. Pitch P₁₄₆ of each flight 146 is preferably between 1/24 and ⅓ revolutions over 1.0 in. In this embodiment, flights 146 are identical and parallel, and thus, radius R_147b of each outer surface 147b is the same, flight angle θ₁₄₆ of each flight 146 is the same and pitch P₁₄₆ of each flight 146 is the same. In particular, in this embodiment, flight angle θ₁₄₆ of each flight 146 is 45° and pitch P₁₄₆ of each flight 146 is 1/12 revolutions over 1.0 in. As best shown in FIG. 13, when the inlet guide 140 is viewed from above along axis 105, flights 146 spiral in a clockwise direction. Thus, flights 136 of rotor 130 and flights 146 of inlet guide 140 spiral in opposite directions. As a result, the angle between flights 136, 146 is the sum of flight angles θ₁₃₆, θ₁₄₆. In embodiments described herein, the sum of flight angles θ₁₃₆, θ₁₄₆ is preferably between 0° and 180°, and more preferably about 90°. In this embodiment, flight angles θ₁₃₆, θ₁₄₆ are 45°, 45°, respectively, and thus, the angle between flights 136, 146 is 90°.

In this embodiment, outer surface 145 also includes a plurality of circumferentially adjacent parallel grooves 149 disposed between each pair of circumferentially adjacent flights 146. Grooves 149 offer the potential to facilitate and assist fluid flow through drive assembly 120.

Referring now to FIGS. 15 and 16, guide shoe 180 is an elongate member having a central axis coaxially aligned with axis 105, a first or upper end 180a, a second or lower end 180b coincident with end 100b, and an outer surface 181 extending axially between ends 180a, 180b. In this embodiment, outer surface 181 includes a convex semi-spherical curved tip 182a at end 180b, a cylindrical section 182b extending axially from end 180a to tip 182a, and a tapered frustoconical surface 182c extending from end 180b. Tapered frustoconical surface 182c terminates between ends 180a, 180b, and thus, does not extend to end 180a. Due to tapered frustoconical surface 182c, tip 182a has a centerline 185 that is oriented parallel to axis 105 and radially offset from axis 185, and further, the outer perimeter of guide shoe 180 measured in a plane oriented perpendicular to axes 105, 185 increases moving axially from tip 182a. This also results in outer surface 181 having a generally oblique cone geometry. It should be appreciated that outer surface 180 is smoothly and continuously contoured. As used herein, the term “continuously contoured” may be used to describe surfaces and profiles that are smoothly and continuously curved so as to be free of sharp edges and/or transitions with radii less than 0.5 in. As best shown in FIG. 15, tapered frustoconical surface 182c is oriented at an acute angle α_182c relative to axes 105, 185. Angle α_182c is preferably between 8° and 15°. In this embodiment, angle α_182c is 10°. Angle α_182c allows the tapered frustoconical surface 182c to pass through the axis 105 such that there is a tapered surface rather than a flat shoulder coming into contact with any potential restrictions or ledges within the wellbore 20.

Referring still to FIGS. 15 and 16, guide shoe 180 also includes a central bore 186 extending axially from end 180a and defining an inner surface 187 within guide shoe 180 Moving axially along throughbore 186 from end 180a, inner surface 187 includes a first cylindrical section 188a extending axially from end 180a, an upward-facing annular planar shoulder 188b, a second cylindrical section 188c, an internally threaded section 188d, an upward-facing annular planar shoulder 188e, and a third cylindrical section 188f. A plurality of ports 189 extend from section 188f to outer surface 181. Third cylindrical section 188f defines an inner fluid cavity 190 within guide shoe 180 that receives fluid during run-in operations. The fluid is distributed from cavity 190 to ports 189. In this embodiment, ports 189 include a plurality of circumferentially-spaced radial ports 189a that extend radially from cavity 190 to outer surface 181 and an axial port 189b that extends axially from cavity 190 to outer surface 181. As best shown in FIG. 16, in this embodiment, guide shoe 180 also includes a plurality of circumferentially-spaced internally threaded bores 195 extending radially from second cylindrical portion 188c to outer surface 181.

Internal threads of threaded section 188d threadably engage mating external threads of threaded section 131g of rotor 130, thereby threadably coupling guide shoe 180 to end 130b of rotor 130. With guide shoe 180 sufficiently threaded onto end 130b (i.e., with end 130b axially abutting shoulder 188e, a set screw 196 (see FIG. 18) is threaded through each bore 195 and into engagement with recess 131f of rotor 130. With the radially inner ends of set screws 196 seated in recess 131f, guide shoe 180 is prevented from moving axially relative to rotor 130. Thus, guide shoe 180 cannot unthread from rotor 130 or rotate relative to rotor 130 with set screws 196 seated in recess 131f.

Referring again to FIG. 3, guide assembly 100 also includes a pair of bearing assemblies 150, 160 that maintain the coaxial alignment of rotor 130 within housing 121, support radial and axial loads between rotor 130 and inlet guide 140/housing 121, support axial loads between housing 121 and guide shoe 180, and allow rotation of rotor 130 and guide shoe 180 relative to housing 121. First bearing assembly 150 is radially positioned between inlet guide 140 and cylindrical section 131b of rotor 130, and axially positioned between spacer 170 and shoulder 132a of rotor 130; and second bearing assembly 160 is radially positioned between housing 121/guide shoe 180 and cylindrical section 131d of rotor 130, and axially positioned between shoulders 126d, 188b.

Referring now to FIG. 17, first bearing assembly 150 supports radial loads and axial thrust loads between rotor 130 and inlet guide 140 while allowing rotor 130 to rotate relative to inlet guide 140. In particular, first bearing assembly 150 includes a radial bearing 151, which supports radial loads between rotor 130 and inlet guide 140 while allowing rotor 130 to rotate relative to inlet guide 140, and a thrust bearing 155, which supports thrust loads between rotor 130 and inlet guide 140 while allowing rotor 130 to rotate relative to inlet guide 140. Thrust bearing 155 is axially compressed between spacer 170 and annular shoulder 142b of inlet guide 140, and radial bearing 151 is positioned axially adjacent thrust bearing 155 between cylindrical sections 131c, 142c of rotor 130 and inlet guide 140, respectively. Thrust bearing 155 is prevented from moving axially by spacer 170 and shoulder 142b, and radial bearing 151 is coupled to thrust bearing 155 such that radial bearing 151 cannot move axially relative to thrust bearing 155.

Referring still to FIG. 17, in this embodiment, radial bearing 151 is a needle roller bearing including an annular race 152 disposed about rotor 130 and a plurality of circumferentially-spaced elongate cylindrical roller elements 153 circumferentially disposed about rotor 130. Race 152 is radially positioned between cylindrical sections 131c, 142c of rotor 130 and inlet guide 140, respectively, and rollers 153 are radially positioned between race 152 and cylindrical section 131c of rotor 130. Race 152 engages cylindrical section 142c of inlet guide 140 and is stationary relative to inlet guide 140 (i.e., race 152 does not rotate relative to inlet guide 140). However, roller elements 153 rotatably engage race 152 and cylindrical section 131c, and thus, rotate relative to race 152 and rotor 130. Each roller element 153 has an axis of rotation oriented parallel to axis 105, thereby allowing rotor 130 to rotate about axis 105 relative to race 152 and inlet guide 140 while transferring radial loads between rotor 130 and inlet guide 140. A cage (not shown) maintains the circumferential-spacing of roller elements 153.

In this embodiment, thrust bearing 155 is a roller bearing including a first annular race 156 disposed about rotor 130, a second annular race 157 disposed about rotor 130 and axially spaced from race 156, and a plurality of circumferentially-spaced cylindrical roller elements 158 disposed about rotor 130 and axially positioned between races 156, 157. First race 156 axially abuts spacer 170 and is stationary relative to spacer 170 (i.e., race 156 does not rotate relative to spacer 170), second race 157 is seated against shoulder 142b and is stationary relative to inlet guide 140 (i.e., race 157 does not rotate relative to inlet guide 140), and roller elements 158 rotatably engage races 156, 157, and thus, rotate relative to races 156, 157. A retaining cover holds the races 156, 157 together until the make-up of spacer 170 and retention cap 175 on externally threaded section 131a of rotor 130 at end 130a holds the bearing 155 in place. Each roller element 158 has an axis of rotation that is oriented perpendicular to axis 105 and intersects axis 105, thereby allowing races 156, 157 to rotate relative to each other. A cage (not shown) maintains the circumferential-spacing of roller elements 158.

Referring now to FIG. 18, second bearing assembly 160 supports radial loads and axial thrust loads between rotor 130 and housing 120 while allowing rotor 130 to rotate relative to housing 121. In particular, second bearing assembly 160 includes a radial bearing 161, which supports radial loads between rotor 130 and housing 121 while allowing rotor 130 to rotate relative to housing 121, and a thrust bearing 165, which supports thrust loads between rotor 130 and housing 121 and upper end 180a of guide shoe 180 while allowing rotor 130 to rotate relative to housing 121. Thrust bearing 165 is axially positioned between radial bearing 161 and shoulder 188b, and radial bearing 161 is axially positioned between thrust bearing 165 and shoulder 126d. Thrust bearing 165 is prevented from moving axially by outer housing lower end 121b and shoulder 188b, and radial bearing 161 is coupled to thrust bearing 165 such that radial bearing 161 cannot move axially relative to thrust bearing 165.

Referring still to FIG. 18, in this embodiment, radial bearing 161 is a needle roller bearing including an annular race 162 disposed about rotor 130 and a plurality of circumferentially-spaced elongate cylindrical roller elements 163 circumferentially disposed about rotor 130. Race 162 is radially positioned between cylindrical sections 131e, 126e of rotor 130 and housing 121, respectively, and rollers 163 are radially positioned between race 162 and cylindrical section 131e of rotor 130. Race 162 engages cylindrical section 126e of housing 121 and is stationary relative to housing 121 (i.e., race 162 does not rotate relative to housing 121). However, roller elements 163 rotatably engage race 162 and cylindrical section 131e, and thus, rotate relative to race 162 and rotor 130. Each roller element 163 has an axis of rotation oriented parallel to axis 105, thereby allowing rotor 130 to rotate about axis 105 relative to race 162 and housing 121 while transferring radial loads between rotor 130 and housing 121. A cage (not shown) maintains the circumferential-spacing of roller elements 163.

In this embodiment, thrust bearing 165 is a roller bearing including a first annular race 166 disposed about rotor 130, a second annular race 167 disposed about rotor 130 and axially spaced from race 166, and a plurality of circumferentially-spaced cylindrical roller elements 168 disposed about rotor 130 and axially positioned between races 166, 167. First race 166 axially abuts race 162 and is stationary relative to race 162 (i.e., race 166 does not rotate relative to race 162), second race 167 is seated against shoulder 188b and is stationary relative to guide shoe 180 (i.e., race 167 does not rotate relative to guide shoe 180), and roller elements 168 rotatably engage races 166, 167, and thus, rotate relative to races 166, 167. A retaining cover holds the races 166, 167 axially together. Each roller element 168 has an axis of rotation that is oriented perpendicular to axis 105 and intersects axis 105, thereby allowing races 166, 167 to rotate relative to each other. A cage (not shown) maintains the circumferential-spacing of roller elements 168.

Referring now to FIGS. 5 and 17, retention cap 175 is generally cylindrical and has a first or upper end 175a disposed in connection sub 110, a second or lower end 175b disposed about rotor 130, and a radially outer surface 175c extending axially between ends 175a, 175b. In addition, retention cap 175 includes a bore 176 extending axially from end 175b and a plurality of circumferentially-spaced internally threaded bores 177 extending radially from outer surface 175c to bore 176. A portion of bore 176 includes internal threads that threadably engage mating external threads of threaded section 131a of rotor 130, thereby threadably coupling retention cap 175 to end 130a of rotor 130. With retention cap 175 sufficiently threaded onto end 130a, a set screw 178 is threaded through each bore 177 and into engagement with recess 131b of rotor 130. With the radially inner ends of set screws 178 seated in recess 131b, retention cap 175 is prevented from moving axially relative to rotor 130. Thus, retention cap 175 cannot unthread from rotor 130 or rotate relative to rotor 130 with set screws 178 seated in recess 131b.

As best shown in FIG. 17, as retention cap 175 is threaded onto end 130a of rotor 130, spacer 170, thrust bearing 155, and inlet guide 140 are axially compressed between ends 175b, 121a. In particular, spacer 170 is axially compressed between retention cap 175 and thrust bearing 155, thrust bearing 155 is axially compressed between spacer 170 and shoulder 142b of inlet guide 140, and inlet guide 140 is axially compressed between thrust bearing 155 and end 121a of housing 121, which threadably engages end 110b of connection sub 110. As previously described, flight surfaces 147b of inlet guide 140 statically engage second cylindrical section 112b of connection sub 110. Thus, retention cap 175, spacer 170, thrust bearing first annular race 156, and rotor 130 rotate relative to housing 121, connection sub 110, inlet guide 140, radial bearing annular race 152, and thrust bearing second annular race 157.

As previously described, in this embodiment, outer surface 181 of guide shoe 180 has a generally oblique cone geometry. However, guide shoes having alternative geometries can also be used in assembly 100 in place of guide shoe 180. Referring now to FIGS. 19A-19D, alternative embodiments of guide shoes 280, 380, 480, 580, respectively, which can be used in place of guide shoe 180, are schematically shown. In FIG. 19A, guide shoe 280 has a central axis 285, a first or upper end 280a configured to attached to lower end 130b of rotor 130, a second or lower end 280b, and an outer surface 281 extending axially between ends 280a, 280b. When guide shoe 280 is attached to rotor 130, axis 285 is coaxially aligned with axis 105. In this embodiment, outer surface 281 is concentrically disposed about axis 285 and includes a cylindrical section 282a extending axially from end 280a and a frustoconical section 282b extending from end 280b to cylindrical section 282a and oriented at an acute angle β_282b relative to axes 105, 285.

In FIG. 19B, guide shoe 380 has a central axis 385, a first or upper end 380a configured to attached to lower end 130b of rotor 130, a second or lower end 380b, and an outer surface 381 extending axially between ends 380a, 380b. When guide shoe 380 is attached to rotor 130, axis 385 is coaxially aligned with axis 105. In this embodiment, outer surface 381 is concentrically disposed about axis 385 and includes a cylindrical section 382a extending axially from end 380a and a frustoconical section 382b extending from end 380b to cylindrical section 382a and oriented at an acute angle β_382b relative to axes 105, 385. Guide shoe 380 further includes a plurality of uniformly circumferentially-spaced ports 383 extending radially from frustoconical section 382b of outer surface 381 to an inner fluid cavity (not shown) extending axially from upper end 380a and lower end 380b. In this embodiment, frustoconical section 382b is oriented at an acute angle β_382b that is greater than the acute angle β_282b at which the frustoconical section 282b of the guide shoe 280 shown in FIG. 19A is oriented.

In FIG. 19C, guide shoe 480 has a central axis 485, a first or upper end 480a configured to attached to lower end 130b of rotor 130, a second or lower end 480b, and an outer surface 481 extending axially between ends 480a, 480b. When guide shoe 480 is attached to rotor 130, axis 485 is coaxially aligned with axis 105. In this embodiment, outer surface 481 is concentrically disposed about axis 485 and includes a convex semi-spherical curved tip 482b at end 480b and a cylindrical section 482a extending axially from end 480a to tip 482b. Guide shoe 380 further includes a plurality of uniformly circumferentially-spaced ports 483 extending radially from tip 482b of outer surface 481 to an inner fluid cavity (not shown) extending axially from upper end 480a and lower end 480b.

In FIG. 19D, guide shoe 580 has a central axis 585, a first or upper end 580a configured to attached to lower end 130b of rotor 130, a second or lower end 580b, and an outer surface 581 extending axially between ends 580a, 580b. When guide shoe 580 is attached to rotor 130, axis 585 is coaxially aligned with axis 105. In this embodiment, outer surface 581 is concentrically disposed about axis 585 and includes a first cylindrical section 582a extending axially from end 580a to a downward-facing annular frustoconical shoulder 582b, a second cylindrical section 582c extending axially from shoulder 582b to a tapered frustoconical surface 582d extending from end 580b to cylindrical section 582c. Second cylindrical section 582c is disposed at a diameter that is less than the diameter of first cylindrical section 582a. Guide shoe 580 further includes a plurality of non-uniformly non-circumferentially-spaced ports 583a. 583b extending radially from tapered frustoconical surface 582d of outer surface 581 to an inner fluid cavity (not shown) extending axially from upper end 580a and lower end 580b. Thus, guide shoe 580 has an eccentric geometry and is eccentrically weighted.

Referring now to FIGS. 1, 3, and 5 during run-in operations, guide assembly 100 is connected to the lower end of liner 50 and advanced downhole with injector head unit 14. As guide assembly 100 leads liner 50 through borehole 20, fluid (e.g., drilling fluid) is pumped from the surface 30 down liner 50 to guide assembly 100. The fluid flows axially through guide assembly 100 between housing 121 and inlet guide 140/rotor 130. As fluid is pumped axially between housing 121 and inlet guide 140, the fluid exerts forces on helical flights 146, which are oriented at angles θ₁₄₆ relative the axial direction (i.e., along axis 105) (see FIG. 11). However, inlet guide 140 is static relative to housing 121, and thus, inlet guide 140 resists the forces and torque applied to flights 146 by the fluid. As a result, inlet guide 140 does not rotate in response to the flow of fluid over helical flights 146, but rather, helical flights 146 direct of flow of the fluid in a generally clockwise direction (when viewed from above) about axis 105 (see FIG. 13). As fluid is pumped axially between housing 121 and rotor 130, the fluid exerts forces on helical flights 136, which are oriented at angles θ₁₃₆ relative the axial direction (i.e., along axis 105) (see FIG. 8). Unlike inlet guide 140, rotor 130 is rotatable relative to housing 121, and thus, rotor 130 rotates in response to the forces and torque applied to flights 136 by the fluid as the fluid flows axially through guide assembly 100. Helical flights 136 extend helically in a counterclockwise direction (as viewed from above) about axis 105 (see FIG. 10), and thus, as the fluid flows between rotor 130 and housing 121, rotor 130 rotates in a clockwise direction (as viewed from above). As previously described, flights 136 of rotor 130 are oriented at about 90° relative to flights 146 of inlet guide 140, and thus, fluid flowing helically around inlet guide 140 impacts flights 136 of rotor 130 at about 90°, which offers the potential to maximize the impact force and associated rotational torque applied to rotor 130.

The lower end 130b of rotor 130 is fixably attached to guide shoe 180, and thus, rotation of rotor 130 relative to housing 121 about axis 105 results in the rotation of guide shoe 180 relative to housing 121 about axis 105. The rotation of the guide shoe 180 allows guide assembly 100 to guide liner 50 around obstructions in the borehole 20. In this embodiment, rotor 130 is concentrically disposed within housing 121, rotates about central axis 105, and flights 136 are uniformly circumferentially-spaced and have the same geometry. Consequently, rotor 130 has a center of mass disposed along rotational axis 105, and thus, is generally rotationally balanced. Guide shoe 180 also rotates about axis 105; however, guide shoe 180 has an eccentric geometry and is eccentrically weighted. In particular, due at least in part to tip 182a being radially offset from axis 105, guide shoe 180 has a center of mass that is offset from rotational axis 105. Consequently, as guide shoe 180 rotates about axis 105, imbalanced forces and associated vibrations are induced, which advantageously offer the potential to enhance the ability of guide assembly 100 to guide liner 50 around obstructions in the borehole 20 and reduce the likelihood of guide assembly 100 getting hung up or stuck downhole.

Referring now to FIGS. 1, 5, 6, 8, 9, and 16, the fluid flowing between rotor 130 and housing 121 flows radially inward through ports 134 into bore 133 of rotor 130, and then from bore 133 through cavity 190 and ports 189 of guide shoe 180 into the borehole 20. The fluid in borehole 20 can then flow up the annulus 24 to the surface 30. During run-in, drilling fluid can be pumped down liner 50 and guide assembly 100, and back up annulus 24 to facilitate the advancement of guide assembly 100 and liner through borehole 20. However, once liner 50 is run to the desired depth/location within borehole 20, cement can be pumped down liner 50 and guide assembly 100, and back up annulus 24 to secure liner 50 in the desired position within borehole 20.

As previously described, imbalanced forces and associated vibrations experienced by guide assembly 100 advantageously offer the potential to enhance the ability of guide assembly 100 to guide liner 50 around obstructions in the borehole 20 and reduce the likelihood of guide assembly 100 getting hung up or stuck downhole. In general, imbalanced forces and associated vibrations can be induced by an eccentric guide shoe and/or an eccentric rotor. In the embodiment of guide assembly 100 shown in FIG. 2, such imbalanced forces and vibrations result from the eccentric geometry and weight distribution of guide shoe 180. However, in other embodiments, the imbalanced forces and associated vibrations are induced by an eccentrically weighted rotor. For example, portions of material can be removed from select locations of a rotor (e.g., drilling holes in one or more helical flights of the rotor, making one helical flight shorter than the other helical flights, etc.) to form an eccentrically weighted rotor.

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 guide assembly for running a liner through a borehole extending through a subterranean formation, the guide assembly having a central axis, a first end configured to be coupled to the liner, and a second end opposite the first end, the guide assembly comprising:

a guide shoe disposed at the second end;

a drive assembly including a radially outer housing and a rotor concentrically disposed in the housing, wherein the rotor is configured to rotate about the central axis relative to the housing about the central axis;

wherein the rotor has a first end distal the guide shoe and a second end fixably coupled to the guide shoe.

2. The guide assembly of claim 1, wherein the rotor includes a plurality of circumferentially-spaced parallel helical flights.

3. The guide assembly of claim 2, wherein the plurality of helical flights of the rotor are radially spaced from the housing.

4. The guide assembly of claim 2, further comprising an inlet guide including a plurality of circumferentially-spaced parallel helical flights.

5. The guide assembly of claim 4, wherein the rotor is configured to rotate relative to the inlet guide.

6. The guide assembly of claim 4, wherein the plurality of helical flights of the inlet guide statically engage a cylindrical inner surface of the outer housing.

7. The guide assembly of claim 4, wherein the plurality of helical flights of the inlet guide spiral about the central axis in a first direction and the helical flights of the rotor spiral about the central axis in a second direction that is opposite the first direction.

8. The guide assembly of claim 7, wherein each of the plurality of helical flights of the rotor are oriented at a flight angle A relative to a reference plane oriented perpendicular to the central axis and each of the plurality of helical flights of the inlet guide are oriented at a flight angle B relative to the reference plane, and wherein the sum of angle A and angle B is between 0° and 180°.

9. The guide assembly of claim 9, wherein the drive assembly includes a first radial bearing, a second radial bearing, an first thrust bearing, and a second thrust bearing;

wherein the first radial bearing is radially positioned between the rotor and the inlet guide and the second radial bearing is radially positioned between the rotor and the housing;

wherein the first thrust bearing is axially positioned between a spacer and the inlet guide and the second thrust bearing is axially positioned between the housing and the guide shoe.

10. The guide assembly of claim 1, wherein the rotor includes a bore extending axially from the second end of the rotor and a port extending radially from an outer surface of the rotor to the bore.

11. The guide assembly of claim 10, wherein the guide shoe includes an inner fluid cavity in fluid communication with the bore of the rotor and a plurality of ports extending from the inner fluid cavity to an outer surface of the guide shoe.

12. A guide assembly for running a liner through a borehole extending through a subterranean formation, the guide assembly having a central axis, a first end configured to be coupled to the tubular, and a second end opposite the first end, the guide assembly comprising:

a guide shoe disposed at the second end;

a drive assembly including a radially outer housing and a rotor rotatably disposed in the housing, wherein the rotor has a first end distal the guide shoe, a second end fixably coupled to the guide shoe, and an outer surface extending from the first end of the rotor to the second end of the rotor, wherein the outer surface of the rotor includes a plurality of circumferentially-spaced parallel helical flights;

an inlet guide disposed about the rotor and axially positioned between the first end of the rotor and the plurality of helical flights of the rotor, wherein the inlet guide has an outer surface including a plurality of circumferentially-spaced parallel helical flights;

wherein each of the helical flights of the rotor spiral about the central axis in a first direction and the plurality of helical flights of the inlet guide spiral about the central axis in a second direction that is opposite the first direction.

13. The guide assembly of claim 12, wherein the rotor is coaxially disposed in the outer housing.

14. The guide assembly of claim 13, wherein the rotor is configured to rotate relative to the inlet guide.

15. The guide assembly of claim 14, wherein the plurality of circumferentially-spaced parallel helical flights of the inlet guide statically engage the outer housing.

16. The guide assembly of claim 12, wherein each of the plurality of helical flights of the rotor are oriented at a flight angle A relative to a reference plane oriented perpendicular to the central axis and each of the plurality of helical flights of the inlet guide are oriented at a flight angle B relative to the reference plane, and wherein the sum of angle A and angle B is between 0° and 180°.

17. The guide assembly of claim 12, wherein the rotor includes a bore extending axially from the second end of the rotor and a plurality of circumferentially-spaced ports extending radially from an outer surface of the rotor to the bore.

18. The guide assembly of claim 17, wherein the guide shoe includes an inner fluid cavity in fluid communication with the bore of the rotor and a plurality of ports extending from the inner fluid cavity to an outer surface of the guide shoe.

19. A guide assembly for running a tubular through a borehole extending through a formation, the guide assembly having a central axis, a first end configured to be coupled to the tubular, and a second end opposite the first end, the guide assembly comprising:

a guide shoe disposed at the second end; and

a drive assembly configured to drive the rotation of the guide shoe about the central axis, wherein the drive assembly includes a radially outer tubular housing and a rotor rotatably disposed within the housing, wherein the rotor has a first end distal the guide shoe and a second end fixably coupled to the guide shoe, wherein the rotor includes a bore extending axially from the second end of the rotor and a port extending radially from an outer surface of the rotor to the bore;

wherein the guide shoe includes an inner fluid cavity in fluid communication with the bore of the rotor and a port extending from the inner fluid cavity to an outer surface of the guide shoe.

20. The guide assembly of claim 19, wherein the rotor includes a plurality of circumferentially-spaced parallel helical flights.

21. The guide assembly of claim 20, further comprising an inlet guide including a plurality of circumferentially-spaced parallel helical flights, wherein the rotor is configured to rotate relative to the inlet guide.

22. The guide assembly of claim 21, wherein the plurality of helical flights of the inlet guide statically engage the outer housing.

23. The guide assembly of claim 22, wherein the plurality of helical flights of the rotor spiral about the central axis in a first direction; and

wherein the plurality of helical flights of the inlet guide spiral about the central axis in a second direction that is opposite the first direction.

24. The guide assembly of claim 23, wherein the guide shoe has an eccentric geometry and is eccentrically weighted.

25. The guide assembly of claim 23, wherein the rotor has an eccentric geometry and is eccentrically weighted.

26. The guide assembly of claim 23, wherein the guide shoe and the rotor have an eccentric geometry and are eccentrically weighted.