Abstract:
A multilateral junction comprises a primary leg and one or more lateral legs. Each end of the primary leg and each lateral leg has an inflatable element therein. A method for installing a multilateral junction includes running a deformed junction to depth and serially or collectively inflating an inflatable element in each leg of said junction to reform said junction.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 60/356,712 filed Feb. 13, 2002, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The hydrocarbon recovery industry has embraced multilateral wellbores to enhance volumetric and qualitative recovery of specified hydrocarbons while minimizing earth surface impact. Multilateral wellbores, simply put, are those where a primary borehole is drilled from the earth&#39;s surface and at least one “lateral” borehole diverges from that primary wellbore somewhere underground. As a practical matter, there are more than one lateral borehole extending from a primary borehole. 
     Multilateral wellbores employ junctions to mate a primary wellbore to its lateral boreholes. Whether the bores be cased or uncased, generally the junction is larger in outside dimension than the primary wellbore through which it must pass to arrive at the site of lateral exit. One way to deal with this issue is to form the junction at the surface and then deform the legs and primary sections thereof so it has a temporary outside dimension smaller than the I.D. of the primary wellbore through which it will be delivered to its installation site. Once at its installation site, the junction is swaged back to near its original shape. Unfortunately, swaging can be damaging to the material of the junction and is effort intensive. 
     SUMMARY 
     A multilateral junction comprises a primary leg and one or more lateral legs. Each end of the primary leg and each lateral leg has an inflatable element therein. 
     A method for installing a multilateral junction includes running a deformed junction to depth and serially or collectively inflating an inflatable element in each leg of said junction to reform said junction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
     FIG. 1 is a perspective view of a multilateral junction in undeformed condition; 
     FIG. 2 is a perspective view of a multilateral junction in deformed condition; 
     FIG. 3 is a perspective view of FIG. 2 with inflatable elements installed therein; 
     FIG. 4 is a perspective view of the junction with elements inflated; and 
     FIG. 5 is a perspective view of the junction with the snobblin bar being pressure reformed. 
    
    
     DETAILED DESCRIPTION 
     Referring initially to FIG. 1, a typical junction shape for installation at the junction between a primary bore and a lateral bore is illustrated. The junction  10  is built prior to being installed in a wellbore, generally at a factory. For the following discussion, different areas of the junction are to be considered separate. They are lateral leg  12 , primary end  14 , primary end  16  and snobblin bar  18 . It is also important to note that for purposes of this application the terms “one end” and “another end” as used with respect to junction  10  are merely used to distinguish between two different areas of the primary borehole section of the junction. They could easily be switched, and have no significance with respect to flow direction or order of the components. A snobblin bar is known in the vernacular of this particular art as that section of a junction having a FIG. 8 appearance where the junction is viewed in cross-section. Such a device as shown in FIG. 1 does not fit through the I.D. of a casing string (not shown) which is generally very slightly larger than the O.D. of, for example, primary end  16 . Thus, in order to deliver junction  10  to the desired deployment location it is a practice within the industry to deform the junction as illustrated in FIG.  2 . 
     Reforming the junction after positioning at the desired location is important to its functionality and has been done in the art by means of a mechanical swage. It is desirable however to avoid the work required with the use of a mechanical swage. The inventor of the present disclosure seeks to inflate the deformed junction, as illustrated in FIG. 2, back to a substantial facsimile of its original shape, as illustrated in FIG.  1 . The different sections of the junction, i.e.,  12 ,  14 ,  16  and  18  as identified above require different pressures to undeform them and each has different maximum pressure limits before which such section will rupture. In one example, section  12  would require in excess of 7000 pounds per square inch (hereinafter “psi”) to resume a round shape whereas primary end portion  14  only requires 3000 psi to be rendered substantially round and would rupture at pressures significantly above 3000 psi (and well before the 7000 psi required to reform leg  12 ). Similar to portion  14 , primary end portion  16  requires approximately 3000 psi to attain a round shape. Again, substantially in excess of 3000 psi at  16  may cause structural problems with the junction. For obvious reasons then, simply pressuring up on the tubing is not an effective way of reforming the junction. Importantly, the snobblin bar  18  is a relatively weak section of the junction and can only maintain about 2500 psi. Substantially more pressure could easily rupture the snobblin bar. 
     The inventor hereof has overcome the problem associated with reforming a deformed junction with fluid pressure by employing three separate inflatable elements which can be seen illustrated in situ in FIG.  3 . Element  20  is disposed within the lateral section  12  of junction  10 , element  22  is located in the primary end  16  and element  24  is located in the primary end  14 . In one embodiment, each of the inflatable elements are packers. It is noted that the inflatable elements  20 ,  22  and  24  are, in this embodiment, installed in the junction after deforming, however, it is possible to have the inflatable elements installed within the junction  10  prior to deforming for ease of insertion. Since each of the elements is independent, different pressures are possible in specific areas of junction  10  which require them. For example, in this embodiment, inflatable element  20  will be pressured to about 7000 psi in order to straighten and round section  12 . Inflatable elements  22  and  24  will each be inflated to about 3000 psi in order to reform those sections of the junction. Because elements  22  and  24  are at about 3000 psi, element  20  is reduced from about 7000 psi after inflation, to about 3000 psi. Referring now to FIG. 4, the snobblin bar  18  is at this point segregated and pressure sealed from areas beyond the individual inflatable elements. This area is to be pressured from another location capable of producing and maintaining a pressure of about 2500 psi, i.e., sufficient to reform the snobblin bar area but avoid rupture. This can be accomplished by providing a fluid inlet anywhere within the area defined by inflatable elements  20 ,  22 ,  24  and the bridging sections of the junction  10 . In this embodiment, inflatable element  24  further includes a feed through arrangement such as that typified by Product number 300-02, commercially available from Baker Oil Tools, Houston, Tex. The feed through device, schematically illustrated at  26 , feeds pressure to the snobblin bar area  18 . Once the 2500 psi pressure has been given sufficient time, the snobblin bar area of junction  10  is reformed as illustrated in FIG.  5 . The inflatable elements may then be removed from the junction and further completion operations undertaken. In one embodiment of the method for creating the junction in the downhole environment, much of which has been disclosed above, the junction  10  is created and then deformed in a pattern known to the art. Inflatable elements are added to the deformed junction although as noted previously can be added prior to deforming. The inflatable elements are inflated either serially or collectively as desired and when set and stabilized, pressure is fed to the snobblin area. After a period of time of about 20 to about 30 minutes, the pressure is relieved from the snobblin area and relieved from the inflatable elements whereafter said elements may be removed from the junction. 
     While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.