Patent Publication Number: US-2023160274-A1

Title: Single acting snap ring guide

Description:
TECHNICAL FIELD 
     The disclosure generally relates to the field of earth or rock drilling (mining), and more particularly to well equipment or well maintenance. 
     BACKGROUND ART 
     Traditional well construction, such as drilling of an oil or gas well, consists of three phases: drilling, lining with casing, and production with tubing. In the drilling phase, rock is cut away until a deposit is reached. This establishes a wellbore or borehole through a series of formations. Each formation through which the well passes must be sealed so as to avoid an undesirable passage of formation fluids, gases, or materials out of the formation and into the borehole or from the borehole into the formation. In addition, it is often desired to isolate both producing and non-producing formations from each other to avoid contaminating one formation with fluids from another formation. 
     Lining the wellbore with casing protects the formation layers and stabilizes the wellbore. Packers and liners are often used in lining the wellbore to separate fluid types. Packers are tools used to form an annular seal between two concentric strings of pipe or between the pipe and the wall of the open hole and are usually set just above the producing zone to isolate the producing interval from the casing annulus or from producing zones elsewhere in the wellbore. At times, it is not desired for the casing to extend all the way to the surface of the wellbore, in which case a liner is used. A liner is a casing string that does not extend to the top of the wellbore, but instead is anchored or suspended from inside the bottom of the previous casing string. 
     Production tubing is run into a drilled well after the casing is run and set in place. Production tubing protects the wellbore casing from wear, tear, and corrosion while providing a continuous bore from the producing zone to the wellhead. When sections of production tubing are run into a wellbore, they often run through a packer or liner top to interconnect them. However, packer bores and liner tops are substantially centered in the wellbore. If the wellbore is deviated, the production tubing will tend to engage the edge of the packer bore or liner top instead of entering it. In order to correct this issue, the production tubing is maneuvered to enter the packer bore or liner top. A guide is attached to the lower end of the production tubing to facilitate entering a packer bore or maneuvering past downhole obstructions. The guide typically includes a muleshoe geometry such that rotation of the muleshoe will allow the end of the guide to bypass the top of a packer or obstruction. This rotation may be accomplished by rotating the entire production tubing from the surface. However, when running the production tubing string into a wellbore, the ability to rotate the tubing string to enter into packer bores or liner tops may be prevented due to control lines attached to the tubing and/or extreme hole angles. When rotation of the production tubing is not feasible, there are self-aligning muleshoe guides available that will rotate as the weight of the production tubing string applied to the guide increases due to the guide setting down on a packer bore or liner top. A guide with a muleshoe geometry will enter the packer bore or liner top after sufficient rotation. After the guide enters the packer or liner top, the bottom end of the guide will typically move back to the original position with the assistance of a spring. In addition, the spring designed for use in the guide is designed for the harsh downhole environment, which incurs a significant cost in material and design. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure may be better understood by referencing the accompanying drawings. 
         FIG.  1    depicts a schematic diagram of a well system making use of a single acting snap ring guide, according to some embodiments. 
         FIG.  2    illustrates an embodiment of a single acting snap ring guide. 
         FIG.  3    is a cross-sectional side view of a single acting snap ring guide. 
         FIG.  4    depicts a cross sectional cutout view of the snap ring in a groove on the upper mandrel. 
         FIGS.  4 A-B  represent a cross-sectional cutaway view of the snap ring in a groove on the upper mandrel and an embodiment of a snap ring to be used in the springless muleshoe guide assembly. 
         FIG.  5    is a cross-sectional, zoomed in side view of the snap ring having jumped from first groove to the next groove on the mandrel. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The description that follows includes example systems that embody embodiments of the disclosure. However, it is understood that this disclosure may be practiced without these specific details. For instance, this disclosure refers to a single acting snap ring guide for entering a packer bore or liner top in a wellbore for subsurface drilling operations in illustrative examples. Embodiments of this disclosure can be also applied to subsea drilling operations. In other instances, well-known instruction instances, protocols, structures and techniques have not been shown in detail in order not to obfuscate the description. 
     Overview 
     When running production tubing string into a wellbore, a guide is often used on the bottom end of the string to assist maneuvering downhole. Guides are used to keep production tubing centered within the wellbore, thus minimizing problems associated with tubing hitting obstructions (e.g., rock ledges or objects) in the wellbore as the tubing is lowered into the well. A guide has been designed that can rotate without a spring. This springless guide has been designed with a helical or spiral groove to guide the orientation of the guide shoe and with a constant section retaining ring (“snap ring”) and at least one circumferential groove for the snap ring to rest and hold the guide shoe in position. When the guide shoe encounters an obstruction, weight of at least the guide itself drives a mandrel of the guide into the guide shoe. As the mandrel is driven down, internal lugs of the guide shoe ride the spiral groove on the mandrel and cause the guide shoe to rotate. If the guide shoe is still in contact with the ledge, and weight is still supplying a force on the guide, the snap ring will be moved out of the current circumferential groove via a beveled edge of the current circumferential groove and snap into a next groove, allowing the guide to continue its rotation as the snap ring moves between circumferential grooves. Once the guide shoe enters the packer or liner top, the guide shoe may stay in its position for future operations. Keeping the guide shoe in the same orientation that allowed it to enter a packer or liner top can increase operational efficiency because it is more likely that it will be in the correct alignment for the next packer bore or liner top encountered in the wellbore. This removes the need for multiple applications of weight to be set down on the guide to index the guide around to the desired orientation. No springs or other mechanisms are required to cause the guide to return to an earlier position. 
     Example Illustrations 
     In the following description of a single acting snap ring guide assembly and other apparatus and methods described herein, directional terms, such as “top”, “bottom”, “upper”, “lower”, etc., are used only for convenience in referring to the accompanying drawings. Specifically, upper and lower are used to refer to different regions, parts, portions, or components of an assembly or equipment when vertically oriented. Additionally, it is to be understood that the various embodiments of the inventive subject matter described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the embodiments. 
       FIG.  1    depicts a schematic diagram of a well system making use of a single acting snap ring guide to run a production tubing string into the wellbore.  FIG.  1    depicts an example of a well system after a vertical wellbore  114  has been drilled. The well system includes a platform  106  positioned on the earth&#39;s surface  104  and extending over and around the wellbore  114 . The wellbore  114  extends vertically from the earth&#39;s surface  104 . 
     In particular,  FIG.  1    depicts the wellbore  114  in which a packer  110  has been inserted downhole. The packer  110  closes off a space between the open hole and a wellbore casing  116  before a production tubing string  112  is run. The packer  110  contains a bore through which the production tubing string can be run. The production tubing string  112  is run into the wellbore  114  with the aid of a guide  108 . The guide  108  is a springless muleshoe guide attached to the lower end of the production tubing string  112 . The guide  108  is designed to rotate, if needed, to enter the packer  110  without rotating the production tubing string  112  and without stroking (i.e., raising and lowering the string). 
       FIG.  2    depicts an embodiment of a single acting snap ring guide assembly  200 . The single acting snap ring guide assembly  200  consists of a lower muleshoe guide  201  concentric to an upper mandrel  202 . A mandrel, as defined herein, may refer to a shaft or tube around which other components are arranged or assembled. The lower muleshoe guide  201  is tapered to allow for orienting around obstructions (e.g., entry into packer bores and liner tops). The tapered bottom end of the lower muleshoe guide  201  has an angular segment  205  and a flat segment  206 . The angular segment  205  is cut away from one side of the bottom portion of the lower muleshoe guide  201  while the rest remains flat. The lower muleshoe guide  201  is attached to the mandrel  202  by a snap ring  204 . The snap ring  204  is housed within the lower muleshoe guide  201  (as indicated by the dashed lines) and in contact with the external surface of the upper mandrel  202 . The illustrated longitudinal location of the snap ring  204  in the springless muleshoe guide assembly  200  is only to illustrate the existence of the snap ring and not a required initial location or resting location. The snap ring  204  is a circular ring that expands and contracts in response to applied forces. The snap ring  204  acts as a wedge, holding the lower muleshoe guide  201  in place relative to the upper mandrel  202 . The upper mandrel  202  consists of two sets of grooves ( 203 ,  205 ). Grooves  203  are a set of grooves that spiral around the upper mandrel  202  while grooves  205  are a set of circumferential grooves orthogonal to a central axis of the upper mandrel  202 . Grooves  205  are beveled to allow the snap ring  204  to move between the grooves. The snap ring  204  engages with grooves  205  to lock the lower muleshoe guide  201  in place relative to the upper mandrel  202 . The snap ring  204  is inside the lower muleshoe guide  201  and outside the upper mandrel  202 , attaching the two pieces. Grooves  203  spiral around the upper mandrel  202  and allow the lower muleshoe guide  201  to rotate and move up the upper mandrel  202  when the snap ring  204  is expanded due to an applied force from the load of components above the single acting snap ring guide assembly  200  weighing down upon the single acting snap ring guide assembly  200  when the flat segment  206  encounters or contacts an obstruction. 
     When the single acting snap ring guide assembly  200  encounters an obstruction (e.g., a packer or liner top) in a wellbore, the flat segment  206  sits down on the liner top. This causes a force due to the weight of the single acting snap ring guide assembly  200  and an attached string above the guide equipment  200  to act on the muleshoe guide  201 . This force causes the snap ring  204  to expand and slide out of the grooves  205 . With the snap ring  204  disengaged from the grooves  205 , the lower muleshoe guide  201  rotates upward relative to the upper mandrel  202  following the grooves  203 . If the bottom of the guide is still sitting on the ledge after the snap ring  204  snaps into a first of the orthogonal grooves  205  and contracts, the snap ring  204  will slide out of the current beveled, orthogonal groove and expand to continue its rotation and upward movement. Once the angular segment  205  is aligned in an orientation that allows the guide assembly  200  to enter the packer bore or liner top, the single acting snap ring guide assembly  200  will drop in, removing the force acting on the lower muleshoe guide  201 . Thus, the snap ring  204  will once again engage with the grooves  205 , and the lower muleshoe guide  201  will stay in this position for future operations. In some cases, the snap ring  204  may not have traveled to one of the grooves  205  when the lower muleshoe guide  201  orients to a position that allows the guide assembly  200  to pass an obstruction. In some embodiments, inertia will allow the snap ring  204  to continue moving along the upper mandrel  202  until the snap ring  204  engages with the next groove  205 . In some embodiments, friction between the snap ring  204  and the exterior surface of the upper mandrel  202  between the grooves  205  will be sufficient to hold the lower muleshoe guide  201  in position without the snap ring  204  engaging a groove  205 . 
       FIG.  3    depicts a cross-sectional side view of the single acting snap ring guide assembly  200  of  FIG.  2   . The cross-sectional view further displays magnified view  320 . The magnified view  320  illustrates the beveled edge of the snap ring  204  and its position between the upper mandrel  202  and the lower muleshoe guide  201  when engaged in one of the circumferential grooves  205 . The snap ring  204  has an inner edge bevel from an approximate midpoint of a top (i.e., towards the upper mandrel and away from the shoe) at 45 degrees to an interior of the snap ring  204  to align with the beveled edge of the circumferential grooves  205 . The alignment of the beveled edges facilitates mating of the snap ring  204  with the beveled edges of circumferential grooves  205 . This reduces the likelihood that the snap ring  204  will catch on an edge of the circumferential grooves  205  or another part of the upper mandrel  202  and maintains a predictable snapping action. The lower muleshoe guide  201  consists of an internal recessed channel or a cutout  307  that houses the snap ring  204  when the snap ring  204  is in an expanded position. The cutout  307  is circumferential about the inner diameter of the lower muleshoe guide  201 . When the snap ring  204  expands, the snap ring  204  slides out of the grooves  205  and into the cutout  307 . The snap ring travels up the upper mandrel  202  in the cutout  307  to the next groove  205 . This sequence of expanding out of the groove  205  into the cutout  307 , traveling up the upper mandrel  202 , and reengaging with the next sequential groove  205  continues until the lower muleshoe  201  orients to pass an obstruction (e.g., enter the packer bore). In some cases, the snap ring  204  may not have traveled to one of the grooves  205  when the lower muleshoe guide  201  orients to a position that allows the guide assembly  200  to pass an obstruction. In some embodiments, the snap ring  204  will remain in the position when the guide assembly  200  can pass the obstruction and hold the lower muleshoe guide  201  in place due to tension of the snap ring  204  and/or inter-surface adhesion between the surface of the snap ring  204  and the exterior surface between the grooves  205  of the mandrel  202 . 
       FIG.  3    depicts a set of lugs  306  internal to the lower muleshoe guide  201  (“internal lugs”) on the upper portion of the lower muleshoe guide  201 . The lugs  306  connect the top end of the lower muleshoe guide  201  to the bottom of the upper mandrel  202 . In some embodiments, the lugs  306  are comprised of individual protrusions spaced along the upper portion of the lower muleshoe guide  201 . In other embodiments, the lugs  306  are comprised of a spiral protrusion. The spiral protrusion aligns with the spacing and angular configuration of the grooves  203  on the upper mandrel  202 . The lugs  306  on the lower muleshoe guide  201  ride in the spiral grooves  203  on the upper mandrel  202 . As the lower muleshoe guide  201  is pushed upward by the force acting on the guide assembly  200 , the lower muleshoe guide  201  rotates due to the lugs  306  riding in the spiral groove  203  on the upper mandrel  202 . 
       FIG.  4    depicts a cross-sectional cutout view of the snap ring  204  in a groove  205  on the upper mandrel of the springless muleshoe guide assembly  200  of  FIG.  2   .  FIG.  4 A  shows the full circumference of a snap ring  400  when positioned in a groove  205  on the upper mandrel  202 . A portion of the lower muleshoe guide  201  is removed to show the entire snap ring  400 . The snap ring  400  is positioned between the inner surface of the lower muleshoe guide  201  and the outer surface of the upper mandrel  202 . The upper mandrel  202  has a set of ring grooves  205  that are circumferential to the upper mandrel  202  and are positioned orthogonal to the central axis of the mandrel  202 . The grooves  205  have edges ( 208 ,  209 ) to allow the snap ring  400  to move out of the grooves  205  when a force is applied on the lower muleshoe guide  201  in an upward direction (i.e., when the lower muleshoe guide  201  engages with an obstruction) and retain the lower muleshoe guide  201  in place when not encountering an obstruction. The edge  208  is shaped to prevent the snap ring  400  from moving out of the groove  205  when the lower muleshoe guide  201  does not encounter an obstruction. For instance, the edge  208  can be a square edge. The edge  209  is shaped to allow the snap ring  400  to move out of the groove  205  when the lower muleshoe guide  201  engages an obstruction. Thus, the edge  209  can be an angled or beveled edge that allows the snap ring  400  to slide out of the groove  205  when the lower muleshoe guide  201  encounters an obstruction. 
       FIG.  4 B  depicts the snap ring for use in the single acting snap ring guide assembly  200  of  FIG.  4 A . The snap ring  400  is an annular fastener with an opening. The snap ring  400  acts as a wedge, holding the lower muleshoe guide  201  in place relative to the mandrel  202 . The snap ring  400  consists of a retaining ring  411  and two ends ( 410 A,  410 B). When a force is applied to the lower muleshoe guide  201  of  FIG.  4 A , the ring  411  takes on an elliptical deformation. Due to the deformation, the ring  411 contacts the groove  205  of  FIG.  4 A  at three or more isolated points long the groove  205 , but not continuously around the circumference. The elliptical deformation causes the ends ( 410 A,  410 B) to separate, allowing the snap ring to disengage from the groove  205 . When the force is removed, the ends ( 410 A,  410 B) return to the original position and engage the next groove  205 . 
       FIG.  5    illustrates a cross-sectional, magnified view of the overlapping portions of the single acting snap ring guide assembly  200  of  FIG.  2   .  FIG.  5    illustrates the position of the snap ring  204  after jumping from one circumferential groove to the next. Snap ring  204  engages the grooves  205 A or  205 B when a force is not applied on the guide  200 . When the lower muleshoe guide  201  encounters an obstruction, the corresponding force causes the snap ring  204  to slide from one groove to the next, sequentially, since the snap ring  204  is attached to the lower muleshoe guide  201  upon which the force is applied. Before weight is set down on the guide, the snap ring  204  is engaged in groove  205 A. When weight is applied to the guide assembly  200 , the snap ring  204  elastically deforms and disengages from groove  205 A. The weight causes the muleshoe guide  201  to rotate upward around spiral groove  203 . For each groove  205  the snap ring  204  jumps, the lower muleshoe guide  201  will rotate an angular distance defined by the longitudinal distance between grooves  205  and angle of the spiral grooves  203 . In some embodiments, each groove  205  will correspond to a 60-degree rotation of the lower muleshoe guide  201  around the upper mandrel  202 . As an example, the mandrel  202  can be made with six of the grooves  205  at a distance apart corresponding to the groove  203  spiraling at an angle adapted to allow the lower muleshoe guide  201  to complete one full, 360-degree rotation. This angular rotation turns the lower muleshoe guide  201  until aligned in an orientation to pass an obstruction. When the lower muleshoe guide  201  passes the obstruction, the force is no longer applied, and the snap ring  204  will engage the next groove  205 B. This action holds the lower muleshoe guide  201  in position. 
     While the previous example referred to a design with  6  ring grooves to allow for a single 360-degree rotation of the lower muleshoe guide, a guide assembly design will vary depending upon a specified maximum degree of rotation or full rotations. Design attributes of the guide assembly that can influence the amount of rotation include length of the upper mandrel, number of ring grooves, and helix pitch or helix angle. Length of the upper mandrel limits longitudinal distance that can be traveled by the lower muleshoe guide. With the maximum longitudinal distance that can be traveled by the lower muleshoe guide and a specified total number of full rotations to allow, the number of ring grooves and either helix pitch or helix angle can be specified in design of the helical groove. 
     While the illustrations above refer to a snap ring, embodiments are not limited to a snap ring. Embodiments use an annular fastener that elastically deforms to exit a ring groove to then travel along a portion of a mandrel between grooves. 
     The embodiments described herein use a single action, caused by an application of force applied due to contact with a packer or liner top, to place the guide in the desired position to enter a packer bore or liner top. Single action is the ability to accomplish work in only one direction. Single action as used herein refers to the rotation of lower muleshoe guide being only in a direction upward with respect to the upper mandrel. The snap ring allows for the single action rotation of the lower muleshoe guide and removes the need for a long coil spring as used in traditional self-aligning tubing guides. By not using long coil springs the risk of potential malfunction or introduction of debris in the hole is reduced. This reduces cost and increase reliability over current guides. 
     While the aspects of the disclosure are described with reference to various implementations and exploitations, it will be understood that these aspects are illustrative and that the scope of the claims is not limited to them. Plural instances may be provided for components, operations or structures described herein as a single instance. Finally, boundaries between various components, operations and data stores are somewhat arbitrary, and particular operations are illustrated in the context of specific illustrative configurations. Other allocations of functionality are envisioned and may fall within the scope of the disclosure. In general, structures and functionality presented as separate components in the example configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the disclosure. 
     Use of the phrase “at least one of” preceding a list with the conjunction “and” should not be treated as an exclusive list and should not be construed as a list of categories with one item from each category, unless specifically stated otherwise. A clause that recites “at least one of A, B, and C” can be infringed with only one of the listed items, multiple of the listed items, and one or more of the items in the list and another item not listed. 
     EXAMPLE EMBODIMENTS 
     Example Embodiments include the following: 
     Embodiment 1: A muleshoe guide assembly comprising: an upper mandrel having a first end adapted to couple to a string and having a plurality of grooves in an external surface of the upper mandrel, wherein the plurality of grooves comprises a helical groove and a set of ring grooves; a lower muleshoe guide concentric to at least a lower portion of the upper mandrel; and a snap ring located within the lower muleshoe guide and attaching the lower muleshoe guide to the upper mandrel. 
     Embodiment 2: The muleshoe guide assembly of Embodiment 1, wherein the set of ring grooves are substantially orthogonal to a longitudinal axis of the upper mandrel. 
     Embodiment 3: The muleshoe guide assembly of Embodiment 1 or 2, wherein the snap ring is positioned in one of the set of ring grooves when engaged with the upper mandrel. 
     Embodiment 4: The muleshoe guide assembly of an of Embodiments 1-3, wherein the snap ring is positioned in a cutout in the inner circumference of the lower muleshoe guide when the snap ring is disengaged from the grooved mandrel. 
     Embodiment 5: The muleshoe guide assembly of any of Embodiments 1-4, wherein the lower muleshoe guide comprises internal lugs adapted to ride in the helical groove wrapping around the upper mandrel. 
     Embodiment 6: The muleshoe guide assembly of any of Embodiments 1-5, wherein at least a first of the set of ring grooves comprises a beveled edge, the beveled edge being towards the first end of the upper mandrel, and the snap ring comprises a bevel adapted to mate with the beveled edge. 
     Embodiment 7: The muleshoe guide assembly of any of Embodiments 1-6, wherein the first ring groove also comprises a squared edge, the squared edge being towards a second end of the upper mandrel. 
     Embodiment 8: A guide assembly comprising: a grooved mandrel having a first end adapted for coupling or connecting, a second end, and having a spiral groove and a set of ring grooves on an external surface of the grooved mandrel; a guide shoe concentric to at least the second end of the grooved mandrel; and an annular fastener that fastens the guide shoe to the grooved mandrel. 
     Embodiment 9: The guide assembly of Embodiment 8, wherein the guide shoe comprises a tapered bottom portion. 
     Embodiment 10: The guide assembly of Embodiments 8 or 9, wherein the annular fastener is adapted to elastically deform when exiting one of the set of ring grooves. 
     Embodiment 11: The guide assembly of any of Embodiments 8-10, wherein each of the set of ring grooves is substantially orthogonal to a longitudinal axis of the grooved mandrel. 
     Embodiment 12: The guide assembly of any of Embodiments 8-11, wherein the guide shoe comprises an internal undercut adapted to accommodate the annular ring when elastically deformed. 
     Embodiment 13: The guide assembly of any of Embodiments 8-12, wherein the guide shoe comprises internal lugs adapted to ride in the spiral groove to allow the guide shoe to rotate about the grooved mandrel. 
     Embodiment 14: The guide assembly of any of Embodiments 8-13, wherein at least a first ring groove of the set of ring grooves comprises a first edge adapted to allow the annular fastener to move out of the first ring groove, the first edge being towards the first end of the grooved mandrel. 
     Embodiment 15: The guide assembly of any of Embodiments 8-14, wherein the first ring groove comprises a second edge adapted to prevent the annular fastener from exiting the first ring groove towards the second end of the grooved mandrel. 
     Embodiment 16: A guide assembly for running string into a wellbore, the guide assembly comprising: a mandrel having a first end that is a coupling end and a second end, and having an external set of ring grooves and an external helical groove; an annular fastener capable of elastic deformation, the annular fastener fastening a guide shoe to the mandrel; and the guide shoe comprising an internal cutout to house the annular fastener when elastically deformed and internal lugs that ride within the external helical groove of the mandrel when the guide shoe rotates about the mandrel, the guide shoe being concentric to at least a lower portion of the mandrel. 
     Embodiment 17: The guide assembly of Embodiment 16, wherein the annular fastener can elastically deform to exit one of the external set of ring grooves. 
     Embodiment 18: The guide assembly of any of Embodiments 16-17, wherein the annular fastener is a snap ring. 
     Embodiment 19: The guide assembly of any of Embodiments 16-18, wherein a number of the external set of ring grooves and the external helical groove are adapted to allow for at least one full rotation of the shoe guide about the mandrel. 
     Embodiment 20: The guide assembly of any of Embodiments 16-19, wherein each of the external set of ring grooves comprises a beveled edge and a squared edge, the beveled edge towards the first end of the mandrel and the squared edge towards the second end of the mandrel.