The present disclosure relates in general to tools or devices for gripping either the outward or inward facing surfaces of a workpiece. In particular, the present disclosure relates to oilfield tools, such as casing running tools (CRTs), used to grip pipe, pipe couplings, or other tubular items with large tolerances and with surface finishes typical of as-rolled steel, particularly in circumstances where premature activation of the CRT prior to full insertion of the workpiece into the CRT would be undesirable.
U.S. Pat. No. 7,909,120 (Slack) describes mechanically-activated tools for gripping tubular articles or workpieces, and improvements to such tools are described in the following patent documents:
CRTs based upon some of or all the above documents incorporate a rotary (primary) latch mechanism that prevents activation of the CRT when in the latched position and permits activation of the CRT when unlatched. Unlatching the primary latch mechanism may require some torque reaction, some compressive axial load, or other remotely-controlled means. After the primary latch mechanism is unlatched, the cage of the CRT may move axially relative to the mandrel of the CRT and cause the slips assembly of the CRT to grip the workpiece. Due to the variable nature of drilling rig operations, pipe characteristics, and human interaction with the drilling rig environment, the primary latch mechanism may become unintentionally unlatched during pipe handling operations, including casing running and casing drilling, and thus result in undesirable activation of the CRT.
A typical normal activation operating sequence for a CRT involves the following steps:
It is advantageous to reduce the time required to activate the CRT to decrease well construction time and cost. This can be accomplished either operationally or mechanically. One method used by drillers to increase operating speed is to rotate the CRT while lowering it onto the workpiece, thus merging the first three steps of the normal activation sequence into a single step, which eliminates the associated transition time between set-down and rotation. Another method for increasing operating speeds is to mechanically eliminate the need to rotate the CRT after set-down through use of a rotary latch release mechanism such as that described in WO 2019/014747 A1 and WO 2020/146936 A1. Both of these methods for reducing the time to activate the CRT can increase the risk of unintentional and undesirable CRT activation resulting from contact with a workpiece prior to full insertion of the workpiece into the CRT or from general contact with other objects.
For purposes of this document, a CRT configured for gripping an internal surface of a tubular workpiece will be referred to as a CRTi, and a CRT configured for gripping an external surface of a tubular workpiece will be referred to as a CRTe. The mandrel of a CRTi and the bell of a CRTe serve similar functions, and for that reason either of these elements may be alternatively referred to herein as a CRT mandrel.
In general terms, the present disclosure teaches non-limiting embodiments of a secondary latch mechanism (alternatively referred to herein as a lockout mechanism) that prevents activation of a gripping tool, such as a CRT, prior to full insertion of a tubular workpiece (e.g., a section of pipe) into the gripping tool. When embodied in a CRT, the lockout mechanism prevents activation of the CRT unless a selected axial load is applied to the CRT bumper by the end of a fully-inserted workpiece.
In the remainder of this specification, lockout mechanisms will be described for exemplary purposes in the context of mechanically-activated casing running tools (CRTs) generally as disclosed in U.S. Pat. No. 7,909,120, and the terms CRT, CRTe, and CRTi will refer to such casing running tools unless specifically stated otherwise.
The lockout mechanism has two operational states, namely, a locked state and an unlocked state, and incorporates means for transitioning between these two operational states. In the locked state, the lockout mechanism resists relative axial movement between the CRT cage and the CRT mandrel, and keeps the CRT slips retracted away from the workpiece. The unlocked state is characterized by the absence of any significant restriction to the normal movement of the components of the CRT. In the unlocked state, the CRT functions as if the lockout mechanism were not present.
There are two separate means for transitioning the lockout mechanism from the locked state to the unlocked state:
The lockout mechanism will return to the locked state from the unlocked state when the following operational sequence is performed:
In general terms, a lockout mechanism in a CRT in accordance with the present disclosure comprises:
As used in the present disclosure, the term “bumper spring” is intended to be understood as denoting an element or apparatus capable of providing an axial biasing force, and which therefore may take any functionally suitable form without departing for the scope of the present disclosure. Non-limiting examples of a bumper spring in accordance with the present disclosure include coil springs, wave springs, Belleville washer stacks, air springs, and hydraulic chambers connected to accumulators.
The mandrel pockets and the holes through the CRT cage wall are arranged such that the lock pins in their locked positions will prevent relative axial movement between the CRT mandrel and the CRT cage, and will hold the CRT cage in a position relative to the CRT mandrel where the CRT slips are retracted away from the workpiece.
The mandrel pockets include a cam surface configured to induce movement of the lock pins toward their unlocked positions when the CRT cage moves axially relative to the CRT mandrel in the direction that causes the CRT slips to engage the workpiece.
The bumper pockets include a cam surface configured to induce movement of the lock pins toward their locked position due to an axial force applied to the CRT bumper by the bumper spring. The stiffness and length of the bumper spring are selected such that the bumper spring provides sufficient axial force to hold the lock pins in their locked positions when no workpiece is in contact with the CRT bumper.
When a pipe or other tubular workpiece applies an axial force to the CRT bumper exceeding the axial biasing force of the bumper spring, the CRT bumper will move to its unlocked position, permitting the lock pins to move from their locked position to their unlocked position, and into the bumper pockets. The axial biasing force of the bumper spring is determined by the spring stiffness and pre-load. If the primary latch mechanism of the CRT is unlatched and the CRT is raised while the CRT bumper is in its unlocked position, then the CRT cage will be able to move axially relative to the CRT mandrel such that the slips will engage the workpiece. If the primary latch mechanism of the CRT is latched and the CRT is raised while the CRT bumper is in its unlocked position, then the CRT cage will not be able to move axially relative to the CRT mandrel, so the bumper spring will urge the CRT bumper to return to its locked position and urge the lock pins to return to their locked positions.
The lockout mechanism may be configured with a mechanical linkage acting between the bumper and the primary latch mechanism such that axial force applied by the workpiece on the bumper in excess of the axial biasing force of the bumper spring generates torque urging the primary latch mechanism to unlatch. Non-limiting examples of mechanical linkages that convert axial force (and associated linear motion) to torque (and associated rotary motion) include mating helical threads and helical track followers.
The lockout mechanism may be configured to automatically unlock at a selected combined torque and axial load envelope (alternatively referred to herein as a lockout release envelope), provided that the selected lockout release envelope is sufficient to unlatch the primary latch of the CRT. The lockout release envelope required to automatically unlock the lockout mechanism will be determined by the force balance on the lock pins—which includes the selected taper angles of the cam surfaces of the bumper pockets and mandrel pockets, and the axial biasing force of the bumper spring. The taper angle of the cam surfaces in the bumper pockets and mandrel pockets may be selected to remain constant, or to vary along the length of the cam surface to alter the axial and radial components of the contact forces with the lock pins as the mechanism components move relative to each other.
Embodiments in accordance with the present disclosure will now be described with reference to the accompanying figures, in which numerical references denote like parts, and in which:
Exemplary Embodiment Incorporated into a CRTe
If CRTe 120 is rotated while being lowered onto workpiece 110 and is misaligned with workpiece 110, then torque and axial load may be transmitted through contact between CRT slips 160 and workpiece 110 prior to workpiece 110 contacting CRT bumper 150. If the combined torque and axial load transmitted through the contact between CRT slips 160 and workpiece 110 is sufficient to unlatch the primary latch mechanism, the lockout mechanism will prevent relative axial movement between CRT cage 140 and CRT mandrel 130, which would extend CRT slips 160 toward workpiece 110.
The lockout mechanism may be configured to automatically unlock at a selected combined axial load and torque envelope (alternatively referred to as the lockout release envelope). The lockout release envelope is determined by the force balance on lock pins 170, which includes the selected taper angles of cam surface 153 of bumper pockets 152 and cam surface 132 of mandrel pockets 131, and the axial biasing force of bumper spring 151.
Exemplary Embodiment Incorporated into a CRTi
If CRTi 220 is rotated while being lowered onto workpiece 210 and is misaligned with workpiece 210, then torque and axial load may be transmitted through contact between CRT slips 260 and workpiece 210 prior to workpiece 210 contacting CRT bumper 250. If the combined torque and axial load transmitted through the contact between CRT slips 260 and workpiece 210 is sufficient to unlatch the primary latch mechanism, the lockout mechanism will prevent relative axial movement between CRT cage 240 and CRT mandrel 230, which would extend CRT slips 260 toward workpiece 210.
The lockout mechanism may be configured to automatically unlock at a selected lockout release envelope determined by the force balance on lock pins 270, which includes the selected taper angles of cam surface 253 of bumper pockets 252 and cam surface 232 of mandrel pockets 231, and the axial biasing force of bumper spring 251.
Physical Embodiment Incorporated into a CRTe
Secondary Latch Mechanism with Primary Latch Release Function
The lockout mechanism of CRTe 420 is configured with a mechanical linkage 445 acting between CRT bumper 450 and primary latch mechanism 434 such that axial force applied by workpiece 410 on CRT bumper 450 in excess of the axial biasing force of bumper spring 451 generates torque urging primary latch mechanism 434 to unlatch. Mechanical linkage 445 comprises track followers 444 on a radially-inward surface of CRT cage 440 that engage helical tracks 455 in a radially-outward surface of CRT bumper 450. The torque generated by mechanical linkage 445 is transmitted from track followers 444 to CRT cage 440 and then to lower latch hooks 436 of primary latch mechanism 434. The torque generated by mechanical linkage 445 is also transmitted from helical tracks 455 in CRT bumper 450 to workpiece 410 through frictional contact with CRT bumper 450 to the drilling rig (not shown) to the upper end of CRTe 420, and then to upper latch hooks 435 of primary latch mechanism 434.
It will be readily appreciated by those skilled in the art that various modifications to embodiments in accordance with the present disclosure may be devised without departing from the scope of the present teachings, including modifications that use equivalent structures or materials hereafter conceived or developed.
It is especially to be understood that the scope of the present disclosure is not intended to be limited to described or illustrated embodiments, and that the substitution of a variant of any claimed or illustrated element or feature, without any substantial resultant change in functionality, will not constitute a departure from the scope of the disclosure.
In this patent document, any form of the word “comprise” is to be understood in its non-limiting sense to mean that any element or feature following such word is included, but elements or features not specifically mentioned are not excluded. A reference to an element or feature by the indefinite article “a” does not exclude the possibility that more than one such element or feature is present, unless the context clearly requires that there be one and only one such element or feature.
Any use herein of any form of the terms “connect”, “engage”, “couple”, “attach”, or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the subject elements, and may also include indirect interaction between the elements such as through secondary or intermediary structure.
Relational and conformational terms such as (but not limited to) “axial” and “cylindrical” are not intended to denote or require absolute mathematical or geometrical precision. Accordingly, such terms are to be understood as denoting or requiring substantial precision only (e.g., “substantially axial” or “generally cylindrical”) unless the context clearly requires otherwise.
Unless specifically noted otherwise, any reference to an element being “generally cylindrical” is intended to denote that the element in question would appear substantially cylindrical in transverse cross-section, although the cross-sectional configuration of the element may vary along its length.
Wherever used in this document, the terms “typical” and “typically” are to be understood and interpreted in the sense of being representative of common usage or practice, and are not to be understood or interpreted as implying essentiality or invariability.
Filing Document | Filing Date | Country | Kind |
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PCT/CA2021/000008 | 2/6/2021 | WO | 00 |
Number | Date | Country | |
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62971733 | Feb 2020 | US |