Expandable screen with auxiliary conduit

[00002] The field of this invention is downhole screens that can be expanded in place and, more particularly screens that include a communication conduit to permit monitoring of downhole conditions.

[00003] Screens have long been used in combination with sand or other proppants to hold open perforations in a formation and to prevent production of particulates from the formation from clogging up the production screens. The common procedure for doing this is known as gravel packing. Eventually, the concept of screen expansion took hold as a possible alternative to gravel packing. In this more recent development, the annular space around the screen was eliminated due to its expansion. The borehole wall would then be in contact with the outermost layer of the screen and the need to deposit sand or other proppants was eliminated in certain applications. Expanding screens are illustrated in U.S. Pat. No. 6,263,972.

[00004] Previously, when gravel packing screens, it was known to provide a control line or conduits for a variety of reasons. Conduits running along a screen could be used to move gravel around a sand bridge during deposition of gravel. Such conduits could also carry fiber optics for the purpose of communicating downhole conditions to the surface. This concept is illustrated in U.S. Pat. No. 6,409,219. Methods for fabricating screens have also been developed. For example, U.S. Pat. No. 6,305,468 illustrates joining layers of a non-expanding screen by putting the layers through a die after rolling them together. This technique allowed welds to be eliminated to improve the reliability of the finished product.

[00005] The prior designs did not address the issue of how to provide surface communication of downhole conditions when using an expanding screen. There are special conditions to consider when providing a communication conduit in conjunction with an expanding screen. The screen tends to shorten in length as it is expanded. The screen is expanded into a borehole wall. The communication conduit is exposed outside the screen during run in and could get damaged. These issues are all addressed by the present invention. The nature of the solutions will be more apparent to those skilled in the art from a review of the description of the preferred embodiment and the claims, which appear below.

[00006] An expanding screen with an associated spirally wrapped exterior control line is disclosed. The control line rests in a spiral trough made up in an exterior perforated jacket. The trough can be made by a pair of ridges disposed substantially parallel to each other or by an ordered spacing of raised dimples in the outer perforated jacket to create spiral troughs. At the screen connections centralizers having a spiral path or paths within can serve a dual function of locating the screen prior to expansion and protecting the control line in the joint area. A fiber optic cable can be placed in the control line.

[00010] Referring to FIG. 1, a screen 10 comprises a perforated base pipe 12 with an overlay of a filter media (not shown). Covering the filter media is an outer shroud 14. Screen 10 is made up in joints 16 for ultimate connection to a packer (not shown) in a manner known in the art. At or near the connections 16, there are disposed one or more centralizers 18. Centralizers 18 have one or more generally spirally oriented paths 20 to accept one or more control lines 22. As shown in FIG. 1, the control line 22 is disposed in a spiral trough 24. Preferably, the depth of the trough is as deep or deeper than the diameter of the line 22. A pair of generally parallel ridges 26 whose pitch can be varied to get the desired number of revolutions of the line 22 in any given section of screen 10 between the joints 16 makes the trough. The ridges 26 can be seen in FIG. 2.

[00011] In this view, the outer shroud 14 is laid out as a flat sheet. It receives perforations 28 which can be stamped in the sheet as well as the troughs 26. It will be appreciated that edges 30 and 32 are ultimately joined to form a spiral seam as opposed to a seam in line with the longitudinal axis of the cylindrical shape formed. The angle on which sheet 34 is rolled will determine the pitch of the trough 24. The seam between edges 30 and 32 can be welded or sealed in another manner. A fiber optic cable or cables 36 can be run within line 22. It can be routed in mechanically during assembly or pumped in after the sections of screen 10 and associated lines 22 are assembled and run into position in the wellbore.

[00012] FIG. 3 is an alternate embodiment to FIG. 2. In FIG. 3 a sheet 36 is perforated with small openings 38. Interspersed among the openings 38 are protrusions 40 with preferably each having an opening 42, although they may be closed as well. Protrusions 40 are in preferably parallel rows such as 44, 46, and 48. There are some protrusions between the rows such as 50 and 52. These help to guide the line or lines 22 in the spiral path created when sheet 36 is rolled into a cylindrical shape making a spiral seam of edges 54 and 56, which can be joined by welding or other ways that are equivalent. The height 58 of the protrusions 40 can be varied or uniform. Preferably the height 58 approximates the diameter of the line or lines 22. The pitch of the spiral trough 24 that can also be created with protrusions 40 can be varied depending on the angle that sheet 36 is rolled, akin to the technique for rolling sheet 34.

[00013] Those skilled in the art will appreciate that using the troughs 24 will protect the line or lines 22 during run in. During expansion, the spiral winding readily accommodated the longitudinal shrinkage in the overall screen length that occurs. The centralizers 18 allow the spiral path to continue from one filter section to the next. The placement of the line or lines 22 is facilitated by the ready access to the trough 24. After expansion, the jacket openings 38 are not pressed into the borehole wall filter cake because the protrusions 40 act as a standoff. Accordingly, the flow to the filter media below the outer shroud 14 is enhanced after expansion of the screen into the borehole wall.

[00014] While the preferred embodiment has been described above, those skilled in the art will appreciate that other mechanisms are contemplated to accomplish the task of this invention, whose scope is delimited by the claims appended below, properly interpreted for their literal and equivalent scope.