Patent Application
20180258718
In the oil and gas industry, tongs are typically used to grip tubular members for connecting and disconnecting two tubular members. More particularly, a first type of tong (i.e., a power tong) rotates a first threaded tubular member, while a second type of tong (i.e., a backup tong) secures a second threaded tubular member against rotation. A single wellbore can have tubular members of varying diameters introduced therein. As the diameter increases, the torque required to achieve satisfactory makeup of a threaded connection may also increase. To achieve high make-up/break-out torque, the tong may use a plurality of jaws, which are fitted with dies, to provide adequate radial gripping force while avoiding deformation of the tubular member. The gripping force may be distributed more evenly circumferentially around the tubular member by increasing the number of jaws around the tubular member.
Conventional power tongs come in different types. One type includes a simple slotted rotary gear and retractable jaws that move radially by rotating the gear. Typically, this type has a limited range of torque due to a limited number of jaws in the tong. A second type includes a simple slotted rotary gear and pivoting jaws. The tubular members gripped by the tong can vary in diameter (e.g., due to industry standard tolerances even between tubular members that are nominally the same diameter). This can result in the pivoting jaws gripping the tubular member in a slightly eccentric position, which can result in uneven loading and potentially deformation of the tubular member, especially in high-torque applications. A third type of power tong includes a rotary gear and retractable jaws that move radially by rotating the gear. The gear includes a first rotary gear segment in a body of the power tong, and a second rotary gear segment in a door of the power tong. When the second rotary gear segment is aligned with the door and a slot (or “throat”) in the body, the door can be opened, with the second rotary gear segment moving along with the door, thereby exposing the throat and allowing the tubular member to be inserted or removed laterally therethrough. This design ensures a generally uniform, centralized gripping of the tubular members. While this design is employed in the oilfield, having a segmented rotary gear complicates the operation of the tongs because it requires precisely positioning the rotary gear with respect to the tong body, so as to allow the door with the second rotary gear segment to swing open, away from the first rotary gear segment, and expose the slot for lateral movement of the tubular member.
Embodiments of the disclosure may provide a tong that includes a cage plate assembly, and a gear that is rotatable relative to the cage plate assembly. The cage plate assembly includes a first portion and a second portion. Whenever a throat of the first portion is properly aligned with a throat of the rotary gear and the tong body, the door of the tong can then be opened. The second portion will move with the door when opened. Both the first and second portion of the cage plate assembly include an upper plate, a lower plate, and an interconnecting structure. The gear defines a slot laterally therethrough. An inner surface of the gear includes at least three sets of cam surfaces. The tong also includes at least three jaws coupled to the cage plate assembly such that the at least three jaws are radially movable with respect to the cage plate assembly and are prevented from circumferential movement with respect thereto. The at least three jaws are engageable with the at least three sets of cam surfaces such that rotation of the gear relative to the cage plate assembly causes the at least three jaws to move in a radial direction between a retracted position and an extended position.
Embodiments of the disclosure may also provide a rotary gear for the tong. The gear includes a substantially C-shaped member. An inner circumferential surface of the member includes one or more sets of cam surfaces. Each set of cam surfaces includes a first cam surface for make-up of tubular connections and a second cam surface for break-out of tubular connections. The first cam surface and the second cam surface are circumferentially-overlapping and positioned at different axial elevations with respect to a central longitudinal axis through the member.
Embodiments of the disclosure may also provide a method for making-up or breaking-out a tubular connection. The method includes opening a door of a tong to expose a throat formed in a gear of the tong, the tong body, and the cage plate assembly. All three throats must be aligned before opening the door. The method also includes introducing a tubular member laterally into the throat while the door is open, closing the door, and rotating the gear relative to the cage plate assembly. Rotating the gear causes the at least three jaws to engage the at least three sets of cam surfaces, respectively, defined on an inner surface of the gear, so as to move the at least three jaws radially inward and into contact with the tubular member. At least one of the three jaws is coupled to the second portion of the cage plate assembly and initially aligned with the slot. The slot is free from any gear segments. The method also includes rotating the tubular using the tong after the at least three jaws contact the tubular member.
The foregoing summary is intended merely to introduce a subset of the features more fully described of the following detailed description. Accordingly, this summary should not be considered limiting.
The accompanying drawing, which is incorporated in and constitutes a part of this specification, illustrates an embodiment of the present teachings and together with the description, serves to explain the principles of the present teachings. In the figures:
It should be noted that some details of the figure have been simplified and are drawn to facilitate understanding of the embodiments rather than to maintain strict structural accuracy, detail, and scale.
Reference will now be made in detail to embodiments of the present teachings, examples of which are illustrated in the accompanying drawing. In the drawings, like reference numerals have been used throughout to designate identical elements, where convenient. The following description is merely a representative example of such teachings.
The tong 100 may include one or more cage plates, which are rotatable relative to the body 110, but may initially be constrained from rotation via a brake band 113 attached to the body 110. Two cage plates, which form a cage plate assembly 136, are shown in
Returning back to
The tong 100 may also include a gear 150. The gear 150 may include a C-shaped member, e.g., a portion of a circular ring with a slot cut in it to allow admission of a tubular member laterally therein. For example, the gear 150 may be a solid, one-piece rotary gear with a circumferential slot (i.e., throat) 151. The tong 100 may not include a separate gear segment, as in some tongs, thus leaving the door 120 free from any part of the gear 150 or separate segment of gear, when the door 120 is hinged open and closed. As such, no part of the gear 150 may move with the door 120 in some embodiments. Further, the slot 151 may be considered an “open throat,” since it is not filled with a gear segment. The gear 150 may be positioned axially-between the cage plates 130, 132 of the body 110. The gear 150 may also be positioned radially-outward from the jaws 140A, 140B, 140C. The gear 150 may be configured to rotate around the axis 112. Accordingly, the gear 150 may be configured to rotate to an open position. In the open position, the slot 151 in the gear 150 is aligned with a corresponding slot (i.e., throat) 111 in the body 110 and a slot 131 in the cage plate assembly 136 to allow a tubular member to be inserted laterally-therethrough or removed laterally-therefrom.
As the jaws 140A, 140B, 140C move radially-inward toward the tubular member 160, the jaws 140A, 140B, 140C may make contact with the outer surface of the tubular member 160. Any slight deviation in the diameter of the tubular member 160 may cause the jaws 140A, 140B, 140C to move slightly radially-outward or slightly radially-inward, depending on whether the tubular member 160 is oversized or undersized.
After engagement of the tubular member, the upper and lower cage plates 130, 132, on both the body 110 and the door 120, may be configured to move in response to continued rotation of the gear 150, transmitted to the cage plates 130, 132 by the jaws 140A, 140B, 140C. Such rotational forces overcome the friction applied by the brake band 113, resulting in the cage plates 130, 132 and thus the jaws 140A, 140B, 140C rotating. In other words, when the jaws 140A, 140B, 140C are engaged with the tubular member 160 and can no longer move radially-inward, the jaws 140A, 140B, 140C begin rotating about the axis 112 together with the gear 150, and the engagement between the slots 133, 134 and ribs 143, 144 drives the cage plates 130, 132 around the axis 112 together with the jaws 140A, 140B, 140C. For example, the rollers 170 may be positioned within a groove 135 on the inside of the cage plates 130, 132. As the cage plates 130, 132 turn, the rollers 170 may force the cage plates 130, 132 to maintain the same axis of rotation as the gear 150. The gear 150 may also include a groove 155 that interfaces with rollers 172, which perform a similar function, maintaining the common rotational axis for the cage plates 130, 132 and the gear 150. This is shown in
The radial distance from the center of the gear 150 to the surface of the first cam surface 156 (with respect to the axis 112) may decrease proceeding in a first circumferential direction (e.g., counterclockwise) until it reaches an end point 157. The radial distance from the center of the gear 150 to the surface of the second cam surfaces 158A, 158B may decrease proceeding in a second circumferential direction (e.g., clockwise) until they reach an end point 159. The radial distance from the center of the gear 150 to the surface of the first cam surface 156 and the surface of the second cam surfaces 158A, 158B may be equal at a circumferential point 153. The first cam surface 156 and the second cam surfaces 158A, 158B may be circumferentially overlapping, but may not intersect axially. The radial distance from the center of the gear 150 to the surface of the first cam surface 156 may be greater than the radial distance to the surface of the second cam surfaces 158A, 158B (e.g., forming a slot) on a first circumferential side of the circumferential point 153. The radial distance from the center of the gear 150 to the surface of the first cam surface 156 may be less than the radial distance to the surface of the second cam surfaces 158A, 158B (e.g., forming a protrusion) on a second circumferential side of the circumferential point 153. This design may allow each jaw 140A, 140B, 140C to travel a larger radial distance toward and away from the tubular member 160, over a shorter circumferential distance compared to conventional designs to ensure that the jaws 140A, 140B, 140C will grip the tubular member 160. This reduction in circumferential travel to effect sufficient radial travel for the jaws 140A, 140B, 140C by providing such overlapping cam-surfaces allows for the use of three jaws that are substantially equally spaced apart in a single, C-shaped rotary gear 150, without a door-segment for the gear 150.
The radial distance from the gripping surface of the jaw to of the first cam surface 146 may decrease proceeding in a first circumferential direction (e.g., counterclockwise from the center of the jaw). The radial distance from the gripping surface of the jaw to the second cam surfaces 148A, 148B may decrease proceeding in a second circumferential direction (e.g., clockwise from the center of the jaw).
For make-up, the method 600 may include rotating the gear 150 in a make-up direction (e.g., clockwise), as at 608. The gear 150 may be rotated by a hydraulic motor. In response to rotating in the make-up direction, the first cam surfaces 156 of the gear 150 may slide along the first cam surfaces 146 of the jaws 140A, 140B, 140C, causing the jaws 140A, 140B, 140C to move radially-inward and grip the outer surface of the tubular member 160. For break-out, the method 600 may include rotating the gear 150 in a break-out direction (e.g., counterclockwise), as at 610. In response to rotating in the break-out direction, the second cam surfaces 158A, 158B of the gear 150 may slide along the second cam surfaces 148A, 148B of the jaws 140A, 140B, 140C, causing the jaws 140A, 140B, 140C to move radially-inward and grip the outer surface of the tubular member 160. In some applications, connections may require more torque for break-out operations than make-up operations, and thus in some embodiments, the second (e.g., break-out) cam surfaces 158A, 158B may have a greater aggregate surface area than the first (e.g., make-up) cam surface 156.
After either 608 or 610, the method 600 may include rotating the tubular member 160 using the tongs 100, as at 612. Once the tubular member 160 is gripped by the jaws 140A, 140B, 140C, continued rotation of the gear 150 may cause the jaws 140A, 140B, 140C, and the tubular member 160 gripped by the jaws 140A, 140B, 140C, to rotate about the axis 112. As mentioned above, rotation of the jaws 140A, 140B, 140C may cause the cage plates 130, 132 to rotate about the axis 112 due to the engagement of the slots 133, 134 and the ribs 143, 144. For right-handed threaded connections, rotation of the tubular member 160 in the clockwise direction may lead to the make-up of the tubular member 160 with another tubular member, and rotation of the tubular member 160 in the counterclockwise direction may lead to the break-out of the tubular member 160 from another tubular member. For left-handed threaded connections, rotation of the tubular member 160 in the counter-clockwise direction may lead to the make-up of the tubular member 160 with another tubular member, and rotation of the tubular member 160 in the clockwise direction may lead to the break-out of the tubular member 160 from another tubular member.
The method 600 may also include rotating the gear 150 in an opposing direction (e.g., counterclockwise after make-up or clockwise after break-out), as at 614. This may cause the jaws 140A, 140B, 140C to move radially-outward and release the tubular member 160. This may also cause the slot 151 in the gear 150 to once again align with the slot 111 in the body 110 (and the slot 131 in the cage plate assembly 136). The method 600 may also include opening the door 120, as at 616. The method 600 may also include removing the tong 100 laterally from the tubular assembly 160, as at 618.
As used herein, the terms “inner” and “outer”; “up” and “down”; “upper” and “lower”; “upward” and “downward”; “above” and “below”; “inward” and “outward”; “uphole” and “downhole”; and other like terms as used herein refer to relative positions to one another and are not intended to denote a particular direction or spatial orientation. The terms “couple,” “coupled,” “connect,” “connection,” “connected,” “in connection with,” and “connecting” refer to “in direct connection with” or “in connection with via one or more intermediate elements or members.”
While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. In addition, while a particular feature of the present teachings may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular function. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” Further, in the discussion and claims herein, the term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment.
Other embodiments of the present teachings will be apparent to those skilled in the art from consideration of the specification and practice of the present teachings disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the present teachings being indicated by the following claims.
