Abstract:
A multilateral well construction and sand control completion. In a described embodiment, a well completion includes first and second wellbores intersecting at an intersection; an assembly positioned in the second wellbore, the assembly including a packer and a well screen, the packer being sealingly engaged with the second wellbore; and a wellbore connector sealingly connected to the assembly, the wellbore connector also being sealingly engaged in the first wellbore on opposite sides of the intersection, and the wellbore connector isolating the intersection from fluid flow through the assembly in the second wellbore and from fluid flowing through the wellbore connector between the opposite sides of the intersection.

Description:
BACKGROUND  
         [0001]    The present invention relates generally to operations performed and equipment utilized in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides a multilateral well construction and sand control completion.  
           [0002]    In multilateral wells (i.e., wells having at least one intersection between wellbores) it is desirable to isolate the wellbore intersection from fluids produced from the wellbores when the intersection occurs in a formation in communication with the intersection. Such isolation achieved by seals, packers, tubular strings, etc. within the wellbores results in a wellbore junction known to those skilled in the art as a TAML level  5  junction.  
           [0003]    It is sometimes desirable to provide sand control in one or more of the intersecting wellbores. For this purpose, well screens have been used in the wellbores and some techniques have been developed for gravel packing and/or performing stimulation operations in the wellbores. However, these existing techniques typically require many trips into the well, and are thus costly and time-consuming to perform, or do not result in at least a TAML level  5  junction being formed.  
           [0004]    From the foregoing, it can be seen that it would be quite desirable to provide improvements in multilateral well construction and sand control completions.  
         SUMMARY  
         [0005]    In carrying out the principles of the present invention, in accordance with an embodiment thereof, a well completion is provided which addresses the above problems in the art.  
           [0006]    In one aspect of the invention, a well completion is provided which includes first and second wellbores intersecting at an intersection. An assembly is positioned in the second wellbore. The assembly includes a packer and a well screen. The packer is sealingly engaged with the second wellbore.  
           [0007]    A wellbore connector is sealingly connected to the assembly. The wellbore connector is also sealingly engaged in the first wellbore on opposite sides of the intersection. The wellbore connector isolates the intersection from fluid flow through the assembly in the second wellbore and from fluid flowing through the wellbore connector between the opposite sides of the intersection.  
           [0008]    In another aspect of the invention, a well completion is provided which includes first and second wellbores intersecting at an intersection. An expandable well screen is positioned in the second wellbore. A wellbore connector is connected to the screen. The wellbore connector is also sealingly engaged in the first wellbore on opposite sides of the intersection. The wellbore connector isolates the intersection from fluid flow through the screen in the second wellbore and from fluid flowing through the wellbore connector between the opposite sides of the intersection.  
           [0009]    These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a schematic cross-sectional view of a first method embodying principles of the present invention;  
         [0011]    [0011]FIGS. 2A &amp; B are schematic cross-sectional views of a second method embodying principles of the present invention; and  
         [0012]    FIGS.  3 A-F are schematic cross-sectional views of a third method embodying principles of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]    Representatively and schematically illustrated in FIG. 1 is a method  10  which embodies principles of the present invention. In the following description of the method  10  and other apparatus and methods described herein, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used only for convenience in referring to the accompanying drawings. Additionally, it is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention.  
         [0014]    As depicted in FIG. 1, the method  10  has resulted in the construction and completion of a main or parent wellbore  12  and a lateral or branch wellbore  14 . The wellbores  12 ,  14  intersect at an intersection  16 , which is formed by positioning a milling/drilling whipstock (not shown in FIG. 1) in the main wellbore  12  below the intersection, and then using the whipstock to laterally deflect mills, drills, etc. to cut through casing  18  lining the main wellbore and drill the branch wellbore extending outwardly from the intersection. Such techniques of forming wellbore intersections are well known to those skilled in the art.  
         [0015]    However, it should be clearly understood that other techniques for forming the wellbore intersection  16  may be used in keeping with the principles of the invention. For example, both the wellbore  14  and the lower portion of the wellbore  12  could branch outwardly from the upper portion of the wellbore  12 , etc. Thus, it will be appreciated that the invention is not limited to the specific details of the various embodiments described herein. Instead, the invention permits a wide variety of alternate methods and configurations.  
         [0016]    After the wellbores  12 ,  14  have been formed, the milling/drilling whipstock is retrieved from the well, and the lower portion of the wellbore  12  is completed as shown in FIG. 1. Specifically, a gravel packing assembly  20  is installed in the wellbore  12 , and the wellbore is gravel packed about the assembly to provide sand control. The assembly  20  as depicted in FIG. 1 includes one or more well screens  22 , a packer  24  and a slurry discharge device  26  interconnected in a tubular string  28 .  
         [0017]    Preferably, the elements of the gravel packing assembly  20  are arranged as depicted in FIG. 1, with the discharge device  26  positioned between the packer  24  and the screens  22 , but other configurations may be utilized, if desired. The packer  24  is set in the casing  18  below the intersection  16 , and gravel and/or proppant  30  is discharged into an annulus  32  between the assembly  20  and the wellbore  12 , using techniques well known to those skilled in the art.  
         [0018]    Note that it is not necessary for the lower portion of the wellbore  12  to be gravel packed in keeping with the principles of the invention. For example, a formation fracturing operation or other stimulation operation, with or without also gravel packing, could be performed in the lower portion of the wellbore  12 . As another example, the screens  22  could be installed in the lower portion of the wellbore  12  without gravel packing or fracturing, the screens could be expanded in the lower portion of the wellbore as described below, or the lower portion of the wellbore could be completed in some other manner, if desired. After gravel packing the lower portion of the wellbore  12 , a deflector  34  is installed in the wellbore  12  below the intersection  16 . A tubular tailpipe  36  attached to the deflector  34  is stung into an upper end of the assembly  20  and is sealingly engaged therewith, for example, with seals  38  received in seal bores  40 . As a result, a passage  42  formed through the deflector  34  is in sealed communication with the interior of the assembly  20  via the tailpipe  36 .  
         [0019]    Alternatively, the deflector  34  could be used in place of the milling/drilling whipstock, in which case the deflector  34  would be installed in the wellbore  12  prior to drilling the branch wellbore  14 . This alternative also eliminates the step of retrieving the drilling/milling whipstock from the well after the branch wellbore  14  is drilled. In this case, it is preferred that the lower main wellbore  12  be completed (i.e., by installing the gravel packing assembly  20  and packing gravel about the screen  22 ) prior to installing the deflector  34  and drilling the branch wellbore  14 . Thus it will be appreciated that the specific order of steps in the methods as described herein, and the specific equipment utilized in these steps, may be altered without departing from the principles of the invention.  
         [0020]    In a unique aspect of the method  10 , the branch wellbore  14  is then completed and the wellbore intersection  16  is isolated from fluid flows in the wellbores  12 ,  14  in only a single trip into the well. Specifically, another gravel packing assembly  44  is attached to a tubular leg  46  of a wellbore connector  48  and conveyed into the well. The wellbore connector  48  is preferably of the type described in U.S. Pat. No. 6,089,320, the entire disclosure of which is incorporated herein by this reference.  
         [0021]    The assembly  44  deflects laterally off of the deflector  34  and enters the wellbore  14 . Another tubular leg  50  of the wellbore connector  48  is not deflected off of the deflector  34 , but instead is sized so that it enters the passage  42  in the deflector. The leg  50  is sealingly engaged in the passage  42 , for example, using seals  52  inserted into a seal bore  54 . A packer or hanger  56  at an upper end of the wellbore connector  48  anchors the wellbore connector and seals between the casing  18  and the wellbore connector.  
         [0022]    The assembly  44  includes an inflatable packer  58 , which is set in the wellbore  14  using techniques well known to those skilled in the art. For example, a ball or other plugging device may be pumped down to the packer  58 , and pressure applied to set the packer. Cement  60  may be flowed into an annulus  62  above the packer  58  and between the leg  46  and the wellbore  14 , if desired, using cement staging equipment and techniques well known to those skilled in the art. One situation in which use of the cement  60  may be desired is when a fracturing operation is to be performed in the wellbore  14 .  
         [0023]    The assembly  44  is very similar to the assembly  20  described above, in that it includes the packer  58 , one or more screens  64  and a slurry discharge device  66  between the packer and screens. Of course, other configurations of the assembly  44  may be used without departing from the principles of the invention. Gravel and/or proppant  68  is discharged into an annulus  70  between the assembly  44  and the wellbore  14  using techniques well known to those skilled in the art.  
         [0024]    Note that it is not necessary for the branch wellbore  14  to be gravel packed in keeping with the principles of the invention. For example, a formation fracturing operation or other stimulation operation, with or without also gravel packing, could be performed in the branch wellbore  14 . As another example, the screens  64  could be installed in the branch wellbore  14  without gravel packing or fracturing, the screens could be expanded in the lower portion of the wellbore as described below, or the wellbore could be completed in some other manner, if desired.  
         [0025]    It may now be fully appreciated that the method  10  results in the isolation of the intersection  16  (and a formation  72  surrounding the intersection) from fluid flowing between the wellbore connector  48  and each of the assemblies  44 ,  20 . Specifically, fluid (indicated by arrow  74 ) flowing from the assembly  20  enters a passage  76  in the leg  50 , and fluid (indicated by arrow  78 ) flowing from the assembly  44  enters a passage  80  in the leg  46  of the wellbore connector  48 .  
         [0026]    The fluid flows  74 ,  78  are commingled in the wellbore connector  48  and the commingled fluid (indicated by arrow  82 ) flows upwardly through a passage  84  extending through an upper tubular end  86  of the wellbore connector. Alternatively, the fluid flows  74 ,  78  could be maintained separate and not commingled in the wellbore connector  48 , if desired, by providing separate tubular strings for these flows, by using “intelligent” completion techniques, etc.  
         [0027]    Each of these fluid flows  74 ,  78  is isolated from the intersection  16  and the formation  72 . The packer  24  isolates the fluid  74  produced through the assembly  20  from fluid in other zones intersected by the main wellbore  12 . The packer  58  isolates the fluid  78  produced through the assembly  44  from fluid in other zones intersected by the branch wellbore  14 . Thus, the method  10  provides a single trip gravel packed completion of the branch wellbore  14 , while also achieving a TAML level  5  wellbore junction.  
         [0028]    Referring additionally now to FIGS. 2A &amp; B, another method go embodying principles of the invention is schematically and representatively illustrated. The method go is somewhat similar to the method  10  described above, and so elements illustrated in FIGS. 2A &amp; B which are similar to those previously described are indicated using the same reference numbers for convenience.  
         [0029]    The method go differs from the method  10  in at least one significant respect in that the gravel packing assembly  44  is not conveyed into the well attached to the wellbore connector  48 . Instead, after the lower portion of the  10  wellbore  12  is completed as described above (installing the assembly  20  and gravel packing) and the deflector  34  is installed, the assembly  44  is conveyed into the well attached to a tubular string  92 , such as a liner string. The deflector  34  deflects the assembly  44  laterally into the wellbore  14 , and the assembly and the tubular string  92  are positioned in the wellbore as depicted in FIG. 2A.  
         [0030]    Preferably, the tubular string  92  has attached thereto an engagement device  94  which engages the deflector  34  or another structure, such as the periphery of a window  96  formed through the casing  18  when the wellbore  14  was drilled. This engagement of the device  94  secures the tubular string  92  and assembly  44  in their proper position in the wellbore  14 .  
         [0031]    The packer  58  is inflated and the wellbore  14  is gravel packed about the assembly  44  as described above. The cement  60  may be placed in the annulus  62  about the tubular string  92 , if desired.  
         [0032]    As depicted in FIG. 2B, the wellbore connector  48  is then installed. The longer leg  46  is deflected by the deflector  34  into the tubular string  92  in the wellbore  14 . The longer leg  46  is sealed therein using seals  98  in seal bore  100 . The shorter leg  50  stabs into the deflector passage  42  and seals therein as described above.  
         [0033]    As with the method  10  described above, the method go provides isolation between the fluid flows  74 ,  78 ,  82  and the formation  72  surrounding the wellbore intersection  16 . A TAML level  5  wellbore junction is, thus, achieved by the method go with a gravel packed completion in the branch wellbore  14 , although two trips are used to complete the branch wellbore.  
         [0034]    Note that it is not necessary in keeping with the principles of the invention for either or both of the wellbores  12 ,  14  to be gravel packed when completed. As described above for the method  10 , the wellbores  12 ,  14  could be completed in some other manner, such as by using the screens  22 ,  64  without gravel packing, expanding the screens in the wellbores with or without also gravel packing, performing other completion operations, such as fracturing operations, etc. Thus, although gravel packed completions are described, the invention is not limited to these types of completions.  
         [0035]    Referring additionally now to FIGS.  3 A-F, another method  110  embodying principles of the invention is representatively and schematically illustrated. In some situations, completion techniques other than gravel packing may be desired for completing either or both of the intersecting wellbores. The method  110  uses expanded screens, rather than gravel packing, for sand control in each of the intersecting wellbores, but it should be understood that any completion technique, or any combination of completion techniques may be used, without departing from the principles of the invention.  
         [0036]    In FIG. 3A, initial steps of the method  110  are depicted as having been performed in the well. A main or parent wellbore  112  is drilled and lined with casing  114 . An open hole portion of the wellbore  112  is drilled through a lower end of the casing  114 .  
         [0037]    An assembly  116  including an expandable well screen  118  and a packer  120  interconnected in a tubular string  122  is positioned in the wellbore  112 , so that the screen  118  is in the open hole portion of the wellbore and the packer  120  is in the cased portion of the wellbore. The packer  120  is set in the casing  114 , and then the screen  118  is expanded outward using techniques well known to those skilled in the art. For example, the screen  118  may be swaged outward, inflated, unfolded, etc., in the wellbore  112 . Preferably, after expansion the screen  118  contacts the walls of the wellbore  112 , aiding in preventing collapse of the wellbore and enhancing sand control.  
         [0038]    A milling/drilling whipstock  124  is then positioned in the wellbore  112  below a desired location for a wellbore intersection  126 . Mills, drills, or other cutting tools are deflected laterally off of the whipstock  124  to form a window  128  through the casing  114 , and to drill a lateral or branch wellbore  130  extending outwardly from the intersection  126 . As stated above for the wellbores  12 ,  14  in the method to, it is not necessary for the wellbore  130  to extend laterally from the wellbore  112 .  
         [0039]    After drilling the wellbore  130 , the whipstock  124  is retrieved and a deflector  132  is installed, as depicted in FIG. 3B. If desired, a tailpipe  134  may be attached below the deflector  132  and stabbed into the assembly  116  when the deflector is installed, as depicted in FIG. 3C. In that case, seals  136  may seal in a seal bore  138  to provide a sealed passage  140  for fluids produced through the assembly  116  into the deflector  132 .  
         [0040]    An assembly  142  including a wellbore connector  144  and an expandable well screen  146  is then conveyed into the well on a tubular string  158 . The screen  146  is attached to a leg  148  of the wellbore connector  144  (via a tubular string  178  extending therebetween), and is deflected laterally into the wellbore  130  by the deflector  132 . A shorter leg  150  of the wellbore connector  144  is stabbed into the passage  140 , and is sealingly engaged therein, such as by using seals  152  received in a seal bore  154 . A packer or hanger  156  attached to an upper tubular end  162  of the wellbore connector  144  may be used to secure and seal the wellbore connector  144  in the casing  114  above the window  128 .  
         [0041]    The tubular string  158  extends through the longer leg  148  of the wellbore connector  142 . Attached at a lower end of the tubular string  158  is a screen expansion tool  160 . After the assembly  142  is properly positioned in the well as depicted in FIG. 3C, the expansion tool  160  is used to outwardly expand the screen  146 . For example, pressure applied through the tubular string  158  to the expansion tool  160  may cause the tool to outwardly deform the screen  146  in a manner known to those skilled in the art.  
         [0042]    As depicted in FIG. 3D, the expansion tool  160  has displaced through and expanded the screen  146  outward in the wellbore  130 . Preferably, the screen  146  contacts the walls of the wellbore  130  when it is expanded.  
         [0043]    Note that the expander tool  160  may be too large to pass through the leg  148  after the screen  146  is expanded. In that case, the expander tool  160  may be left in the lower end of the assembly  142  after the screen  146  is expanded. For example, the expander tool  160  may be detached from the tubular string  158  and remain below the expanded screen  146  when the tubular string is retrieved from the well, as depicted in FIG. 3E. Otherwise, the expander tool  160  may be retrieved from the well along with the tubular string  158 .  
         [0044]    In FIG. 3E it may also be seen that it is not necessary for the packer  156  to be used on the upper end  162  of the wellbore connector  144 . Instead, a packer  164  having a tailpipe  166  attached thereto may be installed after the tubular string  158  is retrieved from the well, as depicted in FIG. 3F. The tailpipe  166  is sealingly received in the upper end  162  of the wellbore connector  144 , for example, using seals  168  received in a seal bore  170 .  
         [0045]    The packer  164  is set in the casing  114 . After setting the packer  164 , a production tubing string  172  is stabbed into the packer  164  and sealingly received therein, for example, using seals  174  received in a seal bore  176 .  
         [0046]    It may now be fully appreciated that the method  10  provides for a sand control completion in the branch wellbore  130  in a single trip into the well, and also provides a TAML level  5  wellbore junction. Sand control in the wellbores  112 ,  130  is provided using expanded screens  118 ,  146 . Note that zonal isolation may be achieved in the branch wellbore  130  by using a packer interconnected in the tubular string  178  between the screen  146  and the leg  148 , if desired.  
         [0047]    Fluid (indicated by arrow  180 ) can now flow into a passage  182  in the leg  148  from the branch wellbore  130 , and fluid (indicated by arrow  184 ) can now flow into a passage  186  in the leg  150  from the lower parent wellbore  112 , and be commingled in the wellbore connector  144  isolated from the wellbore intersection  126  and a formation  188  surrounding the intersection. The commingled fluids (indicated by arrow  190 ) can then flow through a passage  192  in the upper end  162  of the wellbore connector  144  and into the tubular string  172  for production to the surface.  
         [0048]    Expandable screens, such as the screens  118 ,  146  may also be used in the methods  10 , go depicted in FIGS. 1 and 2A &amp; B. For example, instead of, or in addition to, gravel packing about the screens  22  and/or  64 , expandable screens may be used to provide sand control.  
         [0049]    In the method go, this use of an expandable screen may be accomplished in the branch wellbore  14  by expanding the screen  64  using any technique (such as swaging, inflating, unfolding, etc.), after the assembly  44  is installed, but prior to installing the wellbore connector  48 . This would eliminate the need for the discharge device  66  and other gravel packing devices in the assembly  44 , unless it is also desired to gravel pack prior to expanding the screen  64 . Similarly, the screen  22  could be expanded in the other wellbore  12 .  
         [0050]    Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to these specific embodiments, and such changes are contemplated by the principles of the present invention. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.