Patent Application
20080277108
The present invention is directed to an apparatus and a method for securely gripping and releasing a tabular segment or stand of tubular segments for use in drilling operations, particularly for hoisting the tubular segment into alignment with a tubular string.
Wells are drilled into the earth's crust using a drilling rig. Tabular strings are lengthened by threadably coupling add-on tubular segments to the proximal end of the tubular string. The tabular string is generally suspended within the borehole using a rig floor-mounted spider as each new tubular segment or stand is coupled to the proximal end of the tubular string just above the spider. A single joint elevator is used to grip and secure the segment or stand to a hoist to lift the segment or stand into position for threadably coupling to the tubular string.
For installing a string of casing, existing single joint elevators generally comprise a pair of hinged body halves that open to receive a tubular segment and close to secure the tubular within the elevator. Elevators are specifically adapted for seeming and lifting tubular members having conventional connections. A conventional connection comprises an internally threaded sleeve that receives and secures an externally threaded end from each of two tubular segments to secure the segments in a generally abutting relationship. The internally threaded sleeve is first threaded onto the end of a first tubular segment to form a “box end.” The externally threaded “pin end” of the second tubular segment is threaded into the box end to complete the connection between the segments. Typical single joint elevators have a circumferential shoulder that forms a circle upon closure of the hinged body halves. The shoulder of the elevator engages the tubular segment under a shoulder formed by the end of the sleeve and the tubular segment. However, conventional single joint elevators cannot grip a tubular segment having integral connections, because there is no sleeve to form a circumferential shoulder.
Conventional elevators are also difficult to use on tabular segments that are not conveniently accessible. For example, casing segments are often moved to the rig floor from a horizontal pipe rack and presented to the rig floor at a “V”-door. A conventional single joint elevator requires enough clearance to close the hinged body halves around the tubular segment. Depending on the length of the tubular and the proximity of the floor or other rig structures, there may be insufficient clearance around the circumference of the tubular segment for gripping with a conventional single joint elevator, often requiring repositioning of the casing segment so that the single joint elevator can grip the tubular segment. Even if repositioning of each segment takes only a few seconds, delays for repeatedly repositioning tubular segments in the V-door consume a substantial amount of rig time.
What is needed is a single joint elevator that is securable to a tubular at any position along the length of the tubular segment, and not only at the sleeve. What is needed is a single joint elevator that is adapted for securing to the tubular segment notwithstanding close proximity of the rig floor or other rig structure. What is needed is a single joint elevator that can grip and lift single tubular segments without repositioning the tabular segment. What is needed is a versatile single joint elevator that facilitates lifting both a tubular segment having integral connections and a tubular segment having conventional connections with a threaded sleeve received onto the end of a threaded tubular segment.
The present invention is directed to a single joint elevator for gripping a tubular member. The single joint elevator comprises a body having a slot for receiving a tubular member. First and second opposing deployable jaws are movably coupled to the body within the slot and moveable between a removed position and a deployed position within the slot, where each jaw has at least one gripping surface for contacting the tubular member. An actuator assembly selectively moves the jaws from the removed position to the deployed position to grip and retain the tubular member within the slot of the body while hoisting the body. The gripping surface of the jaws may be selected from the group consisting of stationary gripping dies and slips. Optionally, the jaws may be outwardly biased, such as with a coil spring, to return to the removed position when the actuator assembly is not biasing the jaws inwardly.
In one embodiment, the actuator assembly includes a cam ring rotationally coupled to the body, and an actuator coupled between the body and the cam ring for imparting rotation of the cam ring, wherein the cam ring has an inner cam surface for inwardly biasing the first and second opposing jaws. The actuator is preferably selected from a linear actuator and a motor coupled to the cams ring through a rotary gear. Optionally, the actuator is a cylinder powered by a pressurized fluid, such as a double-acting cylinder, for forcibly rotating the cam ring between a removed position and a deployed position. The first and second jaws that are cammed by the inner cam surface may be pivotally or slidably coupled to the body.
In a further embodiment, the actuator assembly includes a first wedge operatively coupled to a first actuator for selectively biasing the first wedge between the body and the first jaw, and a second wedge operatively coupled to a second actuator for selectively biasing the second wedge between the body and the second jaw. The first and second actuators may be cylinders powered by a pressurized fluid, such a double-acting cylinder for forcibly moving the wedges back and forth between a removed position and a deployed position. The first and second jaws that engage the wedges may be pivotally or slidably coupled to the body.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings wherein like reference numbers represent like parts of the invention.
The present invention is directed to a single joint elevator for releasably securing a tubular segment to a cable, rope, line or other hoisting member for lifting the tubular segment into position for being threadably coupled to a pipe string suspended in a borehole. One embodiment of the invention comprises a generally horseshoe-shaped body having a slot for receiving a tubular segment, and opposing jaws that deploy to grip the tubular segment within the slot of the body. The body is adapted for supporting the jaws, and also for being lifted and for transferring the weight of the tubular segment to a cable, rope, line or other hoisting member. An actuator assembly selectively moves the jaws from a removed position to a deployed position to grip and retain the tubular segment within the slot of the body while hoisting the body. Bach jaw has a removed position permitting entry of the tubular into the slot, and a deployed position to grip the tubular within the slot. The deployable jaw is either rotatably or translatably moved from its removed position to its deployed position and may be pneumatically, hydraulically, and/or electrically actuated.
The actuator assembly may include a first wedge operatively coupled to a first actuator for selectively biasing the first wedge between the body and the first jaw, and a second wedge operatively coupled to a second actuator for selectively biasing the second wedge between the body and the second jaw. Such an actuator assembly provides independent operation of the jaws. Alternatively, the actuator assembly may include a cam ring rotationally coupled to the body, and an actuator coupled between the body and the cam ring for imparting rotation of the cam ring, wherein the cam ring has an inner cam surface for inwardly biasing the first and second opposing jaws. Use of a cam surface allows for coordinated movement of the jaws using a single actuator, which may be a pressurized fluid-powered cylinder or a rotary gear coupled to a motor.
In one embodiment, an exemplary cam ring has a generally elliptical inner cam surface for symmetrically deploying the gripping jaws upon rotation of the cam ring in a first direction and releasing the jaws to retract upon rotation of the cam ring in the opposite direction. It should be recognized that a cam ring employing an elliptical cam surface can deploy the gripping jaws by rotation of the cam in either direction. The jaws are deployed when a minor axis of the cam surface ellipse is rotationally biased toward the jaw, because the jaw is restrained from rotating with the cam and is gradually biased toward the center of the ellipse. The jaws are able to move to a fully removed position when the cam is rotated to a point where the major axis of the ellipse is aligned with the jaws. The eccentricity of the cam surface effects both the maximum distance that the jaws can be moved together (i.e., the difference in the lengths of the between the major and minor axis) and also the amount of cam rotating force that will be transferred to the jaws as a gripping force. It should also be recognized that the cam surface does not need to be a true ellipse, but may have any profile that is designed to achieve sufficient jaw travel and gripping forces. Furthermore, the cam surface may be interrupted or fragmented, since it is anticipated that the cam ring will typically not be rotated more than about 45 degrees in either direction from the major axis. Furthermore, the cam surface does not need to be “double-acting” as an elliptical surface extending in either direction from the major axis, but could be “single acting” with a gradually reducing radial distance in only one rotational direction. A single acting cam ring should include a separate single acting cam surface for each jaw and should be pitched for coordinated simultaneous deployment with a single actuator. For example, even a continuous elliptical surface that has the potential to be “double-acting” will preferably have its rotation limited so that the cam surface functions as a single-acting cam surface. Rotational limits increase the accuracy and reliability of positioning the cam ring with the jaws in the fully removed position.
Each jaw is moveably supported by the body. Preferably, the jaws are either pivotally or slidably coupled to the body. Accordingly, the actuator assembly engages and biases the jaws to pivot or to slide from a removed position to a deployed position to grip the tubular.
Each deployable jaw preferably comprises a slip or gripping die. In one embodiment, gripping dies are pivotally secured to the jaw and rotating toward the tubular to tighten the grip. The jaws may have sloped-back inserts that are spring offset upward. Once the jaws have been energized against the tubular segment, the weight of the tubular segment will force the inserts downward and into the tubular wall. In another embodiment, each jaw comprise one or more grooves for slidably receiving tabs, keys, or guides for imposing a predetermined path for movement of a slip within the jaw. Each slip may comprises a contact surface, such as a removable insert or gripping die, which may comprise a textured surface adapted for gripping contact with the external wall of the tubular segment received into the slot.
As used herein, the term “single joint elevated” is intended to distinguish the elevator from a string elevator that is used to support the weight of the entire pipe string. Rather, a “single joint elevator” is used to grip and lift a tabular segment as is necessary to add or remove the tubular segment to or from a tubular string. Furthermore, a pipe or tubular “segment”, as that term is used herein, is inclusive of either a single pipe or tubular joint or a stand made up of multiple joints of a pipe or other tubular that will be lifted as a unit. In the context of the present disclosure, a tubular segment does not include a tubular string that extends into the well.
The body 20 has a slot 12 in one side for receiving the tubular segment 16 and supports a cam ring 40 for selective rotation generally about a axis 17 of the cam ring. The central axis of the cam ring 40 is preferably positioned to substantially intersect a centerline 18 of the slot 12 in order to receive the tubular segment generally centered within the cam ring 40. It is also preferable for the axis 17 of the cam ring 40 to be positioned to substantially intersect a line 19 extending between the lugs 23 so that once the concentrically received tubular segment has been gripped and lifted, the tubular segment will hang straight downward.
The cam ring 40 includes a plurality of slots 22, each slot having a constant radius of curvature about the axis of rotation 17. Each slot 22 slidably receives a post 21 that is fixedly secured to the body 20 and positioned to allow the cam ring 40 to rotate relative to the body 20, while preventing translation of the cam ring 40 relative to the body. It is preferable to limit the arc of the slot 22 to about 30 to 45 degrees in order to limit the extent to which the cam ring 40 will rotate relative to the body 20 and avoid weakening of the cam ring 40. One reason to limit rotation of the cam ring 40 is to prevent the possibility that over-rotation of the cam ring 40 will cause an unintended re-deployment of the jaws 30. Accordingly, it should be recognized that the slots 22 and posts 21 cooperate to allow only portions 43 of the inner cam surface 41 to operate and cam the jaws 30.
A cylinder 42 has a first end pivotally secured to the body 20 and a second end pivotally secured to the cam ring 40. Applying fluid pressure within the cylinder 42 causes the cylinder rod 42a to extend. Because the cam ring 40 is rotationally secured, the extension of the cylinder 42, as configured in
First and second jaws 30 are each slidably secured to the body 20 using a pin, tongue, or blade 32 that extends into a slot, groove, or track 31 in the body. The tracks 31 are directed toward the axis of rotation 17 to allow the jaw 30 to deploy between a removed position (as shown in
When the handling of the tubular segment has been completed, the single joint elevator 10 is released from the tubular segment 16 by retracting the cylinder 42 to the position of
When the handling of the tubular segment has been completed, the single joint elevator 50 is released from the tubular segment 16 by retracting the cylinder 62 to the position of
The terms “comprising,” “including,” and “having,” as used in the claims and specification herein, indicate an open group that includes other elements or features not specified. The term “consisting essentially of,” as used in the claims and specification herein, indicates a partially open group that includes other elements not specified, so long as those other elements or features do not materially alter the basic and novel characteristics of the claimed invention. The terms “a,” “an” and the singular forms of words include the plural form of the same words, and the terms mean that one or more of something is provided. The terms “at least one” and “one or more” are used interchangeably.
The term “one” or “single” shall be used to indicate that one and only one of something is intended. Similarly, other specific integer values, such as “two,” are used when a specific number of things is intended. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition, or step being referred to is an optional (not required) feature of the invention.
It should be understood from the foregoing description that various modifications and changes may be made in the preferred embodiments of the present invention without departing from its true spirit. The foregoing description is provided for the purpose of illustration only and should not be construed in a limiting sense. Only the language of the following claims should limit the scope of this invention.
