Patent Application
20130175051
Lock assemblies are ubiquitous in the downhole drilling and completions industry. One common type of lock assembly involves locking a plug, choke, pressure holding device, tool, etc. in place by radially extending a plurality of dogs into engagement with corresponding features of a radially disposed tubular. In order to accommodate the dogs, windows must be formed in a mandrel or other component of the tubular string, with relatively narrow struts located between each window presenting likely failure points when the string experiences high pressure situations. This results in the need to balance the width of the dogs and the width of the struts, as making either too small can result in failure of the system (e.g., inability of the dogs to lock the string in place and/or fracture of the struts due to heavy loading). In view of these issues and the prevalence of dog type locking systems in the industry, advances and alternatives in the field of lock assemblies are always well received.
A lock assembly including a mandrel having at least one window therein, at least one dog corresponding to the at least one window and radially extendable therethrough, wherein the at least one dog is operatively arranged for engaging at least one feature of a tubular radially disposed with the mandrel, and at least one seal element arranged for sealing the mandrel with respect to the tubular, the at least one seal operatively positioned with respect to the at least one dog for maintaining the mandrel solely in compression against the at least one dog during fluid pressure loading on the mandrel in either longitudinal direction.
A method of locking an assembly including engaging at least one dog of an assembly with a profile of a tubular radially disposed with the assembly, loading the assembly in either longitudinal direction by pressurizing a fluid, the assembly including at least one seal element for sealing the assembly with respect to the tubular, and maintaining the assembly solely in compression against the at least one dog regardless of the longitudinal direction of the loading.
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
Referring now to
The dogs 16 and 18 are arranged to be extended from the mandrel 12 for engagement with corresponding recesses 24 and 26 in the tubular 14 in order to lock the assembly 10, and therefore the string of which it is a part, with respect to the tubular 14. The dogs 16 and 18 could be radially extendable according to any known arrangement. For example, in the embodiment of
In
When loaded in the opposite direction as indicated by an arrow 36 in
Advantageously, as described above, the mandrel 12 is put into compression only, which is more readily handled by the aforementioned dog-type mandrels, particularly the struts of the mandrels, as opposed to tension (e.g., due to the alternating window-strut arrangement described above). That is, for example, a seal element installed upstream from the dog and/or window, with respect to the direction of loading, will prevent a portion of the mandrel being put into tension. By positioning a single seal element between a pair of dogs, the mandrel is sufficiently sealed in both axial loading directions. It is additionally noted that the assembly 10 can be further strengthened by closely setting the tolerances of the dogs 16 and 18 in their respective recesses. That is, with the close tolerances, after the mandrel 12 compresses or buckles some relatively nominal degree (e.g., 0.01 inches), the non-engaged one of the dogs will engage a profile of its corresponding recess for supporting the assembly 10 by enabling the tubular 14 to pick up the loading.
A lock assembly 40 according to another embodiment, but providing the same benefits noted above, is shown in
In
While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.
