The downhole drilling and completion industry in recent years has increasingly discovered uses for optical fiber in signal conductance and sensory applications for the downhole environment. In view of the harshness of that environment, the delicate optical fibers must be protected yet disposed optimally to sense desired parameters to conduct signals to desired end devices.
In a sensory capacity, the fiber must be exposed to the parameter being measured to be able to register that parameter, strain as a parameter presents a particular difficulty because of the need for the fiber to be protected but also to be exposed to the strain in the environment being sensed. Solutions to the foregoing are well received by and beneficial to the art.
Disclosed herein is a fiber support arrangement for a downhole tool which includes at least one tubular and at least one bracket positioning the at least one tubular spaced radially from a downhole tool and lacking contact therewith. At least two fibers are supported at the at least one tubular with at least two of the at least two fibers having a different helical angle from one another relative to an axis of the downhole tool.
Further disclosed is a method for supporting fibers at a downhole tool. The method includes strain transmissively mounting each of at least two fibers at a downhole tool in radial spaced relation to the downhole tool without contact therewith and in different helical angles relative to an axis of the downhole tool.
Further disclosed is a method for supporting fibers at a downhole tool including disposing a support at a downhole tool, wherein the support is radially outwardly positioned of the downhole tool. Supporting the support with at least two brackets axially spaced from each end of the downhole tool such that the downhole tool is lacking contact with the support and mounting at least two fibers at the support such that the at least two fibers lack contact with the downhole tool and have different helical angles relative to an axis of the downhole tool.
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.
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The fiber support arrangement 10 comprises at least one end ring or bracket and as illustrated two end rings 30 and 32 each having at least two fiber pass throughs 34A, 34B and 36A, 36B, respectively and which may be sized to allow pass through of a fibers 46A, 46B, respectively alone or the fibers 46A, 46B inside of conduits 44A, 44B, respectively. End rings 30 and 32 have a radial dimension y sufficient to ensure a clearance between the sand screen assembly 12 (or other downhole tool) and a fully assembled fiber support arrangement 10 such that contact between the fiber support arrangement 10 and the sand screen assembly 12 (or other downhole tool) does not occur. The end rings 30, 32 may be fully annular structures or may be segmented as desired.
One of the pass throughs 34A and 36A of each of the end rings 30, 32 is positioned radially inwardly of a tubular 38 while the other of the pass throughs 34B, 36B is positioned radially outwardly of the tubular 38. These radial positional relationships allow the fiber 46A and the conduit 44A positioned radially inwardly of the tubular 38 to have a different helical angle with respect to an axis of the downhole tool 12 than the fiber 46B and the conduit 44B positioned radially outwardly of the tubular 38.
The tubular 38, which may be metal, is perforated and extends from the end ring 30 to the other end ring 32, the perforations being identified with the numeral 40. The fiber conduits 44A are at an inside dimension surface 42 and the fiber conduits 44B are at an outside dimension surface 43 of the tubular 38, and in one embodiment are strain transmissively disposed thereat. It is to be understood that in other embodiments, the fiber conduits 44A, 44B are disposed to facilitate the fibers 46A, 46B therein measuring or sensing temperature, seismic, pressure, chemical composition, etc. The conduits 44A, 44 B may be metal tubes such as quarter inch, eighth inch or sixteenth inch stainless steel tubulars, for example. In one embodiment, the conduits 44A, 44B are welded by, for example, an induction welding technique to their respective surfaces 42, 43 of tubular 38. In another embodiment, the fiber conduits 44A, 44B are mechanically or adhesively attached to the surfaces 42, 43 (it is to be understood that adhesive processes are intended to include soldering and brazing processes). Broadly stated, any means of attachment of the fiber conduits 44A, 44B to the tubular 38 that allows for, in one embodiment, transmission of strain in the tubular 38 to the fiber conduits 44A, 44B without significant loss of magnitude or at least a reliably predictable loss in magnitude or in other embodiments facilitating or at least not hindering the measurement or sensing of such properties as seismic, temperature, pressure, chemical composition, etc. is sufficient for purposes of the invention disclosed herein. It is to be understood that combinations of sensitivities are also contemplated wherein one or more of the exemplary properties are sensed or combinations including at least one of the exemplary properties are sensed.
In order to ensure optimal function of the fibers 46A, 46B installed in the fiber conduits 44A, 44B, consideration must be given to the means of attachment of the fiber conduits 44A, 44B to the tubular 38. This is particularly true if a welding process or other heat intensive process is to be used for the affixation of the fiber conduits 44A, 44B to the tubular 38. Depending upon the heat to be applied and the resistance to heat damage a particular type of optical fiber 46A, 46B exhibits, it is possible to place the fiber 46A, 46B in the conduit 44A, 44B before welding (or other heat process) or alternatively creates a requirement to place the fiber 46A, 46B in the conduit 44A, 44B after welding (or other heat process).
Regardless of process of attachment, the fibers 46A, 46B (either before or after conduit attachment) are installed in the conduits 44A, 44B, the conduits 44A, 44B or the fibers 46A, 46B being adapted to allow the fibers 46A, 46B to sense the target property. In one embodiment the fibers 46A, 46B are embedded in a strain transmissive potting substance such as for example, epoxy inside the conduits 44A, 44B. Such substance ensures that strain in the conduits 44A, 44B, transmitted thereto by the tubular 38, is in turn transmitted to the fibers 46A, 46B where it will effect a frequency shift in the transmission wavelength of the fibers 46A, 46B thus indicating at a remote location a strain and its magnitude.
In one embodiment of the support arrangement 10, a strip of perforated material is helically wound about an axis and welded at sides thereof to create the tubular form. This method is known to the art but pointed out here for the purpose of noting that the conduits 44A, 44B may be strain transmissively or otherwise disposed at the strip before the strip is helically wound, as the strip is helically wound or after the strip is helically wound, as desired. If the conduits 44A, 44B are disposed at the strip before it is helically wound the conduits 44A, 44B must be positioned nonparallel to one another to assure non-common helical angles between them after the strip has been helically wound. In the event the conduits 44A, 44B are to be attached after the strip is wound i.e. after tubular 38 is formed, then it is desirable to helically wind the conduits 44A, 44B first and install them to the tubular 38 as helical coils prior to strain transmissive disposition thereof.
The completed tubular 38 and conduits 44A, 44B are disposed between the end rings 30 and 32 and secured there permanently. The conduits 44A, 44B, as shown extend beyond the end rings 30 and 32 through pass throughs 34A, 34B and 36A, 36B, respectively, and then to connectors (not shown).
As is illustrated, the conduits 44A, 44B are spaced from the sand screen assembly shroud 20 so as to make no contact therewith when installed. As is illustrated, the fiber support arrangement 10 is attached to the base pipe 14 axially outside of the attachment points of the screen filter media 18 and shroud 20 and may be at the ends of such base pipe 14, if desired. As one of skill in the art will anticipate, one means of attachment of the end rings 30 and 32 to the base pipe 14 is by welding as shown.
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Additional embodiments having three tubulars or more substantially concentrically nested within each other with fiber conduits attached to inner or outer surfaces thereof are also contemplated. Having conduits positioned between tubulars may facilitate mechanical attachment of the conduits to the tubulars via swaging of the tubulars toward one another, thereby sandwiching the conduits therebetween. It should also be noted that any of the tubulars 38, 138A, 138B, 238A, 238B, 338A and 338B could be combined in an embodiment as long as the fibers are spaced from the downhole tool and at least two of the fibers have different helical angles from each other.
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.