Abstract:
The present invention provides a recess within an expandable downhole tubular, such as an expandable sand screen. The recess resides within the wall, such as the outer shroud of an expandable sand screen. The recess serves as a housing for instrumentation lines, fiber optics, control lines, or downhole instrumentation. By placing the lines and instrumentation within a wall of the expandable downhole tool, the tool can be expanded into the wall of the wellbore without leaving a channel outside of the tool through which formation fluids might vertically migrate. The recess is useful in both cased hole and open hole completions. In one embodiment, the recess serves as a housing for an encapsulation which itself may house instrumentation lines, control lines, and downhole instrumentation.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to well completions using expandable components. More particularly, the present invention relates to a profiled recess incorporated into an expandable sand screen or other expandable downhole tubular. The profiled recess houses instrumentation lines or control lines in a wellbore.  
           [0003]    2. Description of Related Art  
           [0004]    Hydrocarbon wells are typically formed with a central wellbore that is supported by steel casing. The steel casing lines the borehole formed in the earth during the drilling process. This creates an annular area between the casing and the borehole, which is filled with cement to further support and form the wellbore.  
           [0005]    Some wells are produced by perforating the casing of the wellbore at selected depths where hydrocarbons are found. Hydrocarbons migrate from the formation, through the perforations, and into the cased wellbore. In some instances, a lower portion of a wellbore is left open, that is, it is not lined with casing. This is known as an open hole completion. In that instance, hydrocarbons in an adjacent formation migrate directly into the wellbore where they are subsequently raised to the surface, typically through an artificial lift system.  
           [0006]    Open hole completions carry the potential of higher production than a cased hole completion. They are frequently utilized in connection with horizontally drilled boreholes. However, open hole completions present various risks concerning the integrity of the open wellbore. In that respect, an open hole leaves aggregate material, including sand, free to invade the wellbore. Sand production can result in premature failure of artificial lift and other downhole and surface equipment. Sand can build up in the casing and tubing to obstruct well flow. Particles can compact and erode surrounding formations to cause liner and casing failures. In addition, produced sand becomes difficult to handle and dispose at the surface. Ultimately, open holes carry the risk of complete collapse of the formation into the wellbore.  
           [0007]    To control particle flow from unconsolidated formations, for example, well screens are often employed downhole along the uncased portion of the wellbore. One form of well screen recently developed is the expandable sand screen, known as Weatherford&#39;s ESS® tool. In general, the ESS® is constructed from three composite layers, including an intermediate filter media. The filter media allows hydrocarbons to invade the wellbore, but filters sand and other unwanted particles from entering. The sand screen is attached to production tubing at an upper end and the hydrocarbons travel to the surface of the well via the tubing. In one recent innovation, the sand screen is expanded downhole against the adjacent formation in order to preserve the integrity of the formation during production.  
           [0008]    A more particular description of an expandable sand screen is described in U.S. Pat. No. 5,901,789, which is incorporated by reference herein in its entirety. That patent describes an expandable sand screen which consists of a perforated base pipe, a woven filtering material, and a protective, perforated outer shroud. Both the base pipe and the outer shroud are expandable, and the woven filter is typically arranged over the base pipe in sheets that partially cover one another and slide across one another as the sand screen is expanded. The sand screen is expanded by a cone-shaped object urged along its inner bore or by an expander tool having radially outward extending rollers that are fluid powered from a tubular string. Using expander means like these, the sand screen is subjected to outwardly radial forces that urge the walls of the sand screen against the open formation. The sand screen components are stretched past their elastic limit, thereby increasing the inner and outer diameter of the sand screen.  
           [0009]    The biggest advantage to the use of an expandable sand screen in an open wellbore like the one described herein is that once expanded, the annular area between the screen and the wellbore is mostly eliminated, and with it the need for a gravel pack. Typically, the ESS® is expanded to a point where its outer wall places a stress on the wall of the wellbore, thereby providing support to the walls of the wellbore to prevent dislocation of particles.  
           [0010]    In modern well completions, the operator oftentimes wishes to employ downhole tools or instruments. These include sliding sleeves, submersible electrical pumps, downhole chokes, and various sensing devices. These devices are controlled from the surface via hydraulic control lines, mechanical control lines, or even fiber optic cable. For example, the operator may wish to place a series of pressure and/or temperature sensors every ten meters within a portion of the hole, connected by a fiber optic line. This line would extend into that portion of the wellbore where an expandable tubular has been placed.  
           [0011]    In order to protect the control lines or instrumentation lines, the lines are typically placed into small metal tubings which are affixed external to the completion tubular and the production tubing within the wellbore. In addition, in completions utilizing known non-expandable gravel packs, the control lines have been housed within a rectangular box. However, this method of housing control lines or instrumentation downhole is not feasible in the context of the new, expandable sand screens now being offered.  
           [0012]    First, the presence of control lines behind an expandable completion tubular or tool interferes with an important function of the expandable tubular, which is to provide a close fit between the outside surface of the tubular and the formation wall (or surrounding casing). This is particularly true with the rectangular boxes normally used. The absence of a close fit between the outside surface of the expandable tubular and the formation wall creates a vertical channel outside of the sand screen, allowing formation fluids to migrate between formations therein, even to the surface. This, in turn, causes inaccurate pressure, temperature, or other readings from downhole instrumentation, particularly when the well is shut in for a period of time.  
           [0013]    There is a need, therefore, for a protective encapsulation for control lines or instrumentation lines which does not hinder the expansion of the expandable tool closely against the formation wall (or casing). There is further a need for an encapsulation which does not leave a vertical channel outside of the expandable tubular when it is expanded against the formation wall (or casing). Still further, there is a need for an encapsulation device which defines a recess in the wall of an expandable sand screen or other expandable downhole tool, and which provides enhanced protection to the control lines/fiber optics as it is expanded against the wall of a wellbore, whether cased or open.  
         SUMMARY OF THE INVENTION  
         [0014]    The present invention provides a recess for housing instrumentation lines, control lines, or fiber optics downhole. In one aspect, the encapsulation defines a recess in the wall of an expandable tubular such as an expandable sand screen. Because the encapsulation resides within the wall of the downhole tool, no vertical channeling of fluids within the annulus outside of the tool, e.g., sand screen, occurs. The recess of the present invention may be employed whether the completion is cased or open. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.  
         [0016]    It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
         [0017]    [0017]FIG. 1 is a section view showing an open hole wellbore with an expandable sand screen disposed therein. A recess of the present invention is shown in cross-section within the wall of the expandable sand screen as an example of an expandable tubular. A traditional rectangular box is shown, in cross-section, running from the surface to the depth of the sand screen.  
         [0018]    [0018]FIG. 2 is a top section view of an expandable sand screen within an open wellbore. Visible is a profiled recess of the present invention residing in the outer layer of the sand screen wall. The sand screen is in its unexpanded state with an enlarged view showing a portion of the sand screen expanded against the formation.  
         [0019]    [0019]FIG. 3 is also a top section view of an expandable sand screen within an open wellbore, with the recess in an alternate configuration. The sand screen is disposed within a cased wellbore in its unexpanded state.  
         [0020]    [0020]FIG. 4 is a top section view of an expandable sand screen before expansion, and a blow-up view of a portion of the expandable sand screen as expanded against a wellbore formation. An alternate embodiment of an encapsulation is demonstrated within the recess. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    [0021]FIG. 1 is a section view showing an open hole wellbore  40 . The wellbore  40  includes a central wellbore which is lined with casing  42 . The annular area between the casing  42  and the earth is filled with cement  46  as is typical in well completion. Extending downward from the central wellbore is an open hole wellbore  48 . A formation  50  is shown adjacent to the wellbore  48 .  
         [0022]    Disposed in the open wellbore  48  is an expandable sand screen  20 . The expandable sand screen  20  is hung within the wellbore  40  from a hanging apparatus  32 . In some instances, the hanging apparatus  32  s a packer (not shown). In the depiction of FIG. 1, the hanging apparatus is a liner  30  and liner hanger  32 . A separate packer  34  is employed to seal the annulus between the liner  30  and the production tubular  44 .  
         [0023]    Also depicted in FIG. 1 is an upper hole encapsulation  12 . The upper hole encapsulation  12  shown is a cross-section of a standard rectangular-shaped box typically employed when running instrumentation lines or cable lines downhole. However, a specially profiled encapsulation may be used which contains arcuate walls, as disclosed in the pending application entitled “Profiled Encapsulation for Use With Expandable Sand Screen,” having S/N No.  
         [0024]    The upper hole encapsulation  12  is shown running from the surface to the depth of the sand screen  20 . The encapsulation  12  is secured to the production tubular  44  by clamps, shown schematically at  18 . Clamps  18  are typically secured to the production tubular  44  approximately every ten meters. The upper hole encapsulation  12  passes through the liner hanger  32  (or utilized hanging apparatus), and extends downward to a designated depth within the wellbore  40 . In the embodiment shown in FIG. 1, the encapsulation  12  extends to the top  21  of the sand screen  20 .  
         [0025]    At or near the depth of the hanging apparatus  32 , the upper hole encapsulation  12  terminates. However, the instrumentation lines or cable lines  62  continue from the upper hole encapsulation  12  and to a desired depth. In FIG. 1, the lines  62  travel to the bottom  25  of the sand screen  20  and the open hole wellbore  48 .  
         [0026]    In accordance with the present invention, the lines  62  reside within a novel recess  10  within the wall of an expandable tubular  20 . The exemplary expandable tubular  20  depicted in FIG. 1 is an expandable sand screen. The recess  10  is visible in FIG. 1 along the outside wall  26  of the sand screen  20 . The recess  10  serves as a housing for instrumentation lines or control lines  62 . For purposes of this application, such lines  62  include any type of data acquisition lines, communication lines, fiber optics, cables, sensors, and downhole “smart well” features.  
         [0027]    [0027]FIG. 2 presents a top section view of a recess  10  of the present invention. In this view, the recess  10  is shown to reside within the outer layer  26  of an expandable tubular  20 . An enlarged section of the tubular  20  is shown expanded against the formation. Again, the depicted expandable tubular  20  is an expandable sand screen. However, it is within the scope of this invention to utilize a profiled recess  10  in any expandable tubular or tool.  
         [0028]    In the embodiment of FIG. 2, the sand screen  20  is constructed from three composite layers. These define a slotted structural base pipe  22 , a layer of filter media  24 , and an outer protecting sheath, or “shroud”  26 . Both the base pipe  22  and the outer shroud  26  are configured to permit hydrocarbons to flow therethrough, such as through perforations (e.g.,  23 ) formed therein. The filter material  24  is held between the base pipe  22  and the outer shroud  26 , and serves to filter sand and other particulates from entering the sand screen  20  and the production tubular  44 . Again, it is within the scope of this invention to utilize a profiled recess  10  in an expandable tool having any configuration of layers.  
         [0029]    In the embodiment shown in FIG. 2, the recess  10  is specially profiled to conform to the arcuate profile of the expandable tubular  20 . To accomplish this, the recess  10  includes at least one arcuate wall  12 . In the embodiment of FIG. 2, the recess  10  defines an inner arcuate wall  12 , an outer arcuate wall  14 , and two end walls  16 . In this embodiment, the outer arcuate wall  14  includes an optional through-opening  14   o  to aid in the insertion of lines  62 . In addition, the control or instrumentation lines  62  are housed within optional metal tubulars  60 . Finally, the embodiment in FIG. 2 includes an optional filler material  64  in order to maintain the one or more lines  62  within the recess  10 . The filler material  64  may be an extrudable polymeric material such as polyethylene, a hardenable foam material such as polyethylene, or other suitable material for holding the lines  62  within the recess  10 .  
         [0030]    Numerous alternate embodiments exist for the configuration of the recess  10  of the present invention. One exemplary alternate configuration for a recess  10  is shown in FIG. 3. There, the recess  10  comprises a first inner arcuate wall  12  and a second outer arcuate wall  14 . The two arcuate walls  12  and  14  meet at opposite ends  16 ′. However, it is within the scope of this invention to provide any shaped recess  10  formed essentially within any layer of the wall  26  of an expandable downhole tubular  20 . When the recess  10  of FIG. 2 or  3  or equivalent embodiments are employed, no vertical channel is left within the annular region  28  between the sand screen and the formation  50  after the sand screen  20  is expanded.  
         [0031]    In another embodiment of the present invention, a separate profiled encapsulation  10 ′ is provided within the recess  10  of the expandable tubular  20 . Such an encapsulation  10 ′ is shown in FIG. 4 where the expandable tubular  20  is again, by way of example only, an expandable sand screen. FIG. 4 presents a portion  20   e  of an expandable sand screen  20  in an expanded state. This demonstrates that the sand screen  20  remains sand tight after expansion. (Note that the expanded depiction is not to scale.) Radial force applied to the inner wall of the perforated base pipe  22  forces the pipe  22  past its elastic limits and also expands the diameter of the base pipe perforations  23 . Also expanded is the shroud  26 . As shown in FIG. 4, the shroud  26  is expanded to a point of contact with the formation  50 . Substantial contact between the sand screen  20  and the formation wall  48  places a slight stress on the formation  50 , reducing the risk of particulate matter entering the wellbore  48 . It also reduces the risk of vertical fluid flow behind the sand screen  20 .  
         [0032]    The encapsulation  10 ′ is shown in FIG. 4 to expand and deform with the recess  10 . The encapsulation  10 ′ is generally shaped to conform to the walls  12 ,  14 ,  16  of the recess  10 . In this manner, the encapsulation  10  defines at least a first arcuate wall  12 ′. In the embodiment of FIG. 4, the encapsulation  10 ′ includes an inner arcuate wall  12 ′, an outer arcuate wall  14 ′, and two end walls  16 ′. The encapsulation  10 ′ serves as the housing for the instrumentation lines or cable lines  62 . The encapsulation  10 ′ may be inserted into the recess  10  either as part of the manufacturing process, or at the well site during downhole tool run-in. The encapsulation  10 ′ is fabricated from a thermoplastic material which is durable enough to withstand abrasions while being pushed or press-fit into the recess  10 . At the same time, the encapsulation  10 ′ material must be sufficiently deformable to allow the encapsulation  10 ′ to generally comply with the expandable tubular  20  as it is expanded against the formation  50 .  
         [0033]    Other embodiments for an encapsulation  10 ′ exist. For example, a crescent-shaped encapsulation (not shown), designed to reside within the profiled recess  10  of FIG. 3 could be employed. In each of the above embodiments, the recess  10  may optionally also house metal tubulars  60  for holding the control or instrumentation lines  62 . Metal tubulars  60  are demonstrated in the embodiments of FIGS. 2 and 3.  
         [0034]    The sand screens  20  depicted in FIGS.  1 - 4  are designed to expand. Expansion is typically done by a cone or compliant expander apparatus or other expander tool (not shown) to provide a close fit between the expandable tubular  20  and the formation  50 . In FIG. 1, the sand screen  20  has already been expanded against an open hole formation  50  so that no annular region remains. The sand screen  20  is thus in position for the production of hydrocarbons. The absence of an annular region substantially prohibits vertical movement of fluid behind the sand screen  20 .  
         [0035]    On the other hand, the expandable tubular  20  in FIG. 2 is in its unexpanded state. An annular region  28  is thus shown in FIG. 2 between the sand screen  20  and the formation  50  within the wellbore  48 . In FIG. 3, the sand screen  20  is again in an unexpanded state. However, in this embodiment recess  10  is disposed within an expandable tubular  20  within a cased wellbore. Casing  52  is shown circumferential to the sand screen  20 , creating an annulus  28 . Further, cement  54  is present around the casing  52 . Perforations  23 ′ are fired into the casing  52  in order to expose hydrocarbons or other formation fluids to the wellbore  48 . Thus, the recess  10  of the present invention has utility for both open hole and cased hole completions.  
         [0036]    While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.