Patent Application
20130319126
Cables, particularly fiber optic cables, are used ubiquitously in the downhole drilling and completions industry. These cables are used for enabling a variety of downhole conditions and parameters, such as temperature, vibration, sound, pressure, strain, etc. to be monitored. Due chiefly to their pervasive use, there is an ever-present desire in the industry for alternate styles of sensing cables, particularly for enhancing the ability to more accurately sense a specific parameter such as strain.
A sensing cable, including an outer cladding; and at least one sensing bundle contained within the cladding, each sensing bundle having a sensing fiber wrapped strain-transmissively by at least one strand.
A method of sensing strain including deploying a cable having at least one at least one sensing bundle contained within a cladding, each sensing bundle having a sensing fiber wrapped strain-transmissively by at least one strand; and transmitting strain to the fiber via the at least one strand.
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 strands 16 are included to facilitate the transfer of strain directly to the fibers 14 so that the cable 10 can be used, e.g., to measure strain in a tubular string or downhole component. To this end, the strands 16 are wrapped, wound, or secured, e.g., helically, spirally, circumferentially, etc., about each of the fibers 14. The number of the strands 16 and the number of turns of the strands 16 per unit length of the fibers 14 may vary in different embodiments. In one embodiment, the strands 16 are stainless steel, although it is to be appreciated that other materials can alternatively be used that exhibit good strain transfer capabilities (e.g., resiliency, ductility, etc.) and resistance to downhole conditions (e.g., maintain good strain transmission to the fibers 14 in high temperature or high pressure environments, etc.).
Similar to the strands 16 being wrapped or wound about the fibers 14 in each of the bundles 12, the bundles 12 in the embodiment of
The cable 10 includes a cladding or sheath 24 to further protect and set the properties of the cable 10 as well as to maintain the assembled arrangement of the components (e.g., to maintain the strands 16, bundles 12, and tubes 20 being wrapped around their corresponding components). Additionally, a cavity 26 formed by the empty space within the cladding 24 located between the bundles 12, the central wire 18, and/or the tubes 20, can be filled with a polymer or other filler material, e.g., for achieving the aforementioned objectives of the cladding 24. In one embodiment the filler material in the cavity 26 is a plastic elastomer, such as that marketed under the trade name Hytrel® and made commercially available from E. I. du Pont de Nemours and Company (DuPont).
An alternate embodiment is illustrated 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.
