Abstract:
This invention relates to the flow control of wellbores including a parent well and at least two lateral branches, each of which may have any direction (from vertical to horizontal). The flow from each lateral branch is independently controlled by a separate flow control device. The flow control devices are located within the parent well to enable an easier and efficient workover and intervention of such devices. In some embodiments, the flow control devices are located above the intersection between the parent well and the at least two lateral branches for similar reasons.

Description:
[0001]    This application claims priority to U.S. Provisional Application Serial No. 60/240,474 filed on Oct. 13, 2000 by Algeroy and Harkness and to U.S. Provisional Application Serial No. 60/298,781 filed on Jun. 15, 2001 by the same inventors. 
     
    
     
       BACKGROUND  
         [0002]    This invention relates generally to lateral and multilateral wells. Specifically, this invention relates to flow control from lateral and multilateral wells.  
           [0003]    Multilateral wells normally include a parent well and at least two lateral branches. Each lateral branch typically intersects and drains at least one hydrocarbon formation. Formation fluid from each lateral branch flows through the relevant lateral branch and is typically commingled in the parent well with fluid from the other lateral branches.  
           [0004]    Operators desire to have the ability to control and regulate the flow of formation fluids from each lateral branch. In order to do so, flow control devices must be included and arranged in the production string so that flow from each lateral branch can be independently controlled.  
           [0005]    U.S. Pat. No. 6,079,494 issued to Longbottom et al. on Jun. 27, 2000 teaches one way in which to independently control the flow from lateral branches. This patent discloses a wellbore having a first and second lateral branch and one parent well. A tubing string is disposed within each lateral branch, and a Y-block connects the two lateral tubing strings to a parent tubing string that provides fluid communication to the surface of the well. A first of the lateral tubing strings includes a flow regulating device (such as a sliding sleeve). A plug is included in the second of the lateral tubing strings, and a ported tubing portion is disposed underneath the plug. A second flow regulating device (such as a sliding sleeve) is included above the Y-block and within the parent tubing string. The first flow regulating device selectively controls/regulates flow from the first formation and into the first lateral branch. Once within the first lateral branch, fluid from the first formation flows upstream, through the Y-block, and into the parent tubing string. Flow from the second formation flows into the second lateral tubing string through an opening at the lower end of the second lateral tubing string. Fluid from the second formation then flows within the second lateral tubing string and into the annulus of the wellbore through the ported tubing. The second flow regulating device then selectively controls/regulates flow of the second formation fluid that is found in the annulus from the annulus region and into the parent tubing string. Once within the parent tubing string, second formation fluid commingles with first formation fluid. Thus, first and second flow regulating device independently and selectively regulate flow from the first and second formation.  
           [0006]    It is highly desirable, however, to have the ability to intervene into the wellbore and workover the flow control devices. Since the first flow regulating device of U.S. Pat. No. 6,079,494 is located within one of the lateral branches, it becomes difficult (if not impossible) and inefficient to access the first flow regulating device.  
           [0007]    The prior art would therefore benefit from well constructions that include at least a first and a second flow control device to independently regulate the flow from at least a first and a second lateral branch (each having any direction), wherein both the first and second flow control devices are located in the parent well thereby facilitating the intervention and workover of such devices.  
         SUMMARY OF THE INVENTION  
         [0008]    This invention relates to the flow control of wellbores including a parent well and at least two lateral branches, each of which may have any direction (from vertical to horizontal). The flow from each lateral branch is independently controlled by a separate flow control device. The flow control devices are located within the parent well to enable an easier and efficient workover and intervention of such devices. In some embodiments, the flow control devices are located above the intersection between the parent well and the at least two lateral branches for similar reasons. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a schematic of one architecture of this invention.  
         [0010]    [0010]FIG. 2 is a more detailed view of the parent well of FIG. 1.  
         [0011]    [0011]FIG. 3 is a schematic of a second architecture of this invention.  
         [0012]    [0012]FIG. 4 is a more detailed view of the parent well of FIG. 3.  
         [0013]    [0013]FIG. 5 is a schematic of a third architecture of this invention.  
         [0014]    [0014]FIG. 6 is a more detailed view of the parent well of FIG. 5.  
         [0015]    [0015]FIG. 7 is a detailed view of one flow control device discussed in this invention.  
     
    
     DETAILED DESCRIPTION  
       [0016]    [0016]FIGS. 1 and 2 illustrate one well architecture of our invention. Our invention is disposed within a wellbore  8  that includes a parent well  12 , a first lateral branch  14 , and a second lateral branch  16 , the first and second lateral branches  14  and  16  intersecting the parent well  12 . A first conduit  22  (for example, a liner and/or a tubing string) is disposed at least partially within the first lateral branch  14 , and a second conduit  24  (for example, a liner and/or a tubing string) is disposed at least partially within the second lateral branch  16 . A junction  26  connects the first and second conduits  24  and  26  to a parent tubing string  28 , which communicates with the surface.  
         [0017]    First lateral branch  14  intersects a first formation  30 , and second lateral branch  16  intersects a second formation  32 . First and second formations  30  and  32  may or may not be part of the same reservoir. Fluid communication between the first formation  30  and the interior of the first conduit  22  is established by at least one opening  34  through first conduit  22 . Openings  34  may comprise sand screens  36  as shown in the figures, or other types of flow communication devices, such as sliding sleeves, or ported tubing. Fluid communication between the second formation  32  and the interior of the second conduit  24  is established by at least one opening  38  through second conduit  24 . Openings  38  may comprise sand screens  40  as shown in the figures, or other types of flow communication devices, such as sliding sleeves, or ported tubing.  
         [0018]    A plug  42  is located within first conduit  22  underneath junction  26 . Plug  42  prevents fluid flow through first conduit  22  and is, in one embodiment, located in the parent well  12 . At least one opening  44  is also located on first conduit  22  underneath plug  42 . At least one opening  44  provides fluid communication between the interior of the first conduit  22  and the annulus  46  region located exterior to first and second conduits  22  and  24 . The at least one opening  44  may comprise a sliding sleeve that selectively provides fluid communication between the interior of the first conduit  22  and the annulus  46  region located exterior to first and second conduits  22  and  24 . In one embodiment, sliding sleeve is controlled from the surface such as by control lines (hydraulic, electric, or fiber optic). A first sealing device  48 , such as a packer, located underneath the at least one opening  44 , sealingly isolates the region above the sealing device  48  from the region below the sealing device  48  (including the lateral branches,  14  and  16 ). Instead of a sliding sleeve, the at least one opening  44  may also comprise ported tubing or any other device which provides fluid communication between the interior of the first conduit  22  and the annulus  46  region located exterior to first and second conduits  22  and  24 .  
         [0019]    Junction  26  may include passageways  50  therethrough to allow fluid communication between its underside and upperside. Parent tubing string  28  includes a first flow control device  18  and a second flow control device  20 . First flow control device  18  may be located above second flow control device  20 . As shown in the Figures, first and second flow control devices  18 ,  20  may be located above the intersection between the parent well  12  and the lateral branches  14 ,  16 .  
         [0020]    First flow control device  18  selectively provides fluid communication between the annulus  46  and the interior of the parent tubing string  28 . When first flow control device  18  is closed, fluid flow is prevented between the annulus  46  and the interior of the parent tubing string  28 . When first flow control device  18  is open, fluid communication is established between the annulus  46  and the interior of the parent tubing string  28 . First flow control device  18  may comprise a sliding sleeve valve which may be a variable choke valve that selectively provides different rates of flow therethrough. First flow control device  18  may be controlled from the surface by way of control line  97 , which may be an electric, hydraulic, or fiber optic control line.  
         [0021]    Second flow control device  20  selectively provides fluid communication through parent tubing string  28 . When second flow control device  20  is closed, fluid flow is prevented within the parent tubing string  28  across the second flow control device  20 . When second flow control device  20  is open, fluid communication is established through the parent tubing string  28  across the second flow control device  20 . Second flow control device  20  may comprise a sliding sleeve valve that includes a shroud  52  and a blocking device  54 , the shroud  52  and blocking device  54  routing fluid from thereunder around the sleeve valve so that the sleeve valve can provide selective flow control of such fluid. The sliding sleeve may also be a variable choke valve that selectively provides different rates of flow therethrough. Second flow control device  20  may be controlled from the surface by way of control line  99 , which may be an electric, hydraulic, or fiber optic control line.  
         [0022]    A second sealing device  56 , such as packer, is located on parent tubing string  28  above first and second flow control devices  18  and  20 . Together, first and second sealing devices  48  and  56  isolate the annulus  46  region located therebetween from the remainder of the parent well  12 , the first lateral branch  14 , and the second lateral branch  16 . Second sealing device  56  includes ports  600  to allow the control lines  100  and  102  to pass therethrough.  
         [0023]    When the operator desires to drain only the first formation  30 , the first flow control device  18  is opened, and the second flow control device  20  is closed. Thus, formation fluid from the second formation  32  flows though openings  38 , into and through second conduit  24 , through junction  26 , into parent tubing string  28 , and up to closed second flow control device  20  which prevents further flow upwards. Formation fluid from the first formation  30  flows through openings  34 , into first conduit  22 , into annulus  46  through the at least one opening  44 , and into parent tubing string  28  through open first flow control device  18 .  
         [0024]    When the operator desires to drain only the second formation  32 , the first flow control device  18  is closed, and the second flow control device  20  is opened. Thus, formation fluid from the first formation  30  flows through openings  34 , into first conduit  22 , into annulus  46  through the at least one opening  44 , and up to closed first flow control device  18  which prevents flow into parent tubing string  28 . Formation fluid from the second formation  32  flows though openings  38 , into and through second conduit  24 , through junction  26 , into parent tubing string  28 , within shroud  53 , through open second flow control device  20 , and continues within parent tubing string  28 .  
         [0025]    When the operator desires to drain both the first and second formations  30  and  32 , the first and second flow control devices  18  and  20  are both opened. Fluid flow from each formation progresses as detailed above until the fluid from the first formation  30  reaches the first flow control device  18 . As the first formation fluid passes through open first flow control device  18 , it becomes commingled with the second formation fluid that is flowing through parent tubing string  28 . Thus, commingled flow from the first and second formations  30  and  32  continues within the parent tubing string  28  to the surface of the wellbore  8 .  
         [0026]    When the operator desires to not flow from either first or second formation  30  and  32 , both the first and second flow control devices  18  and  20  are closed. Thus, fluid from the first formation  30  is restricted within the annulus  46  by first flow control device  18 , and fluid from the second formation  32  is restricted by second flow control device  20  within parent tubing string  28  (underneath second flow control device  20 ).  
         [0027]    By selectively opening and/or closing the first and/or second flow control devices  18  and  20 , the operator can independently control the flow from first and second formations  30  and  32 . By selectively choking first or second flow control devices  18  and  20 , the operator can selectively control the rate of flow from first and second formations  30  and  32 .  
         [0028]    Since both first and second flow control devices  18  and  20  are located above the junction  26  (above the intersection between the parent well  12  and the lateral branches  14 ,  16  and not within the lateral branches), an operator may more easily intervene and workover the devices  18  and  20 . The devices  18  and  20  may thus be replaced, fixed, etc. without having to access either lateral branch  14  or  16 .  
         [0029]    [0029]FIGS. 3 and 4 illustrate a second well architecture of our invention. This well architecture is somewhat similar to that of FIGS. 1 and 2, and corresponding reference numbers will therefore remain the same. Wellbore  8  also includes a parent well  12 , a first lateral branch  14 , and a second lateral branch  16 , the first and second lateral branches  14  and  16  intersecting the parent well  12 . A first conduit  22  (for example, a liner and/or a tubing string) is disposed at least partially within the first lateral branch  14 , and a second conduit  24  (for example, a liner and/or a tubing string) is disposed at least partially within the second lateral branch  16 . A junction  26  connects the first and second conduits  24  and  26  to a parent tubing string  28 , which communicates with the surface.  
         [0030]    First lateral branch  14  intersects a first formation  30 , and second lateral branch  16  intersects a second formation  32 . First and second formations  30  and  32  may or may not be part of the same reservoir. Fluid communication between the first formation  30  and the interior of the first conduit  22  is established by at least one opening  34  through first conduit  22 . Openings  34  may comprise sand screens  36  as shown in the figures, or other types of flow communication devices, such as sliding sleeves, or ported tubing. Fluid communication between the second formation  32  and the interior of the second conduit  24  is established by at least one opening  38  through second conduit  24 . Openings  38  may comprise sand screens  40  as shown in the figures, or other types of flow communication devices, such as sliding sleeves, or ported tubing.  
         [0031]    First conduit  22  includes a first flow control device  100 . Second conduit  24  includes a second flow control device  101 . Both the first flow control device  100  and the second flow control device  101  may be located above the intersection of the first and second lateral branches  14  and  16  and the parent well  12 . Both the first flow control device  100  and the second flow control device  101  are located below the junction  26 .  
         [0032]    First flow control device  100  selectively provides fluid communication through first conduit  22 . When first flow control device  100  is closed, fluid flow is prevented within the first conduit  22  across the first flow control device  100 . When first flow control device  100  is open, fluid communication is established through the first conduit  22  across the first flow control device  100 . First flow control device  100  may comprise a sliding sleeve valve that includes a shroud  152  and a blocking device  154 , the shroud  152  and blocking device  154  routing fluid from thereunder around the sleeve valve so that the sleeve valve can provide selective flow control of such fluid. The sliding sleeve may also be a variable choke valve that selectively provides different rates of flow therethrough. First flow control device  100  may be controlled from the surface by way of control line  202 , which may be an electric, hydraulic, or fiber optic control line.  
         [0033]    Second flow control device  101  selectively provides fluid communication through second conduit  24 . When second flow control device  101  is closed, fluid flow is prevented within the second conduit  24  across the second flow control device  101 . When second flow control device  101  is open, fluid communication is established through the second conduit  24  across the second flow control device  101 . Second flow control device  101  may comprise a sliding sleeve valve that includes a shroud  252  and a blocking device  254 , the shroud  252  and blocking device  254  routing fluid from thereunder around the sleeve valve so that the sleeve valve can provide selective flow control of such fluid. The sliding sleeve may also be a variable choke valve that selectively provides different rates of flow therethrough. Second flow control device  101  may be controlled from the surface by way of control line  302 , which may be an electric, hydraulic, or fiber optic control line.  
         [0034]    Sealing devices  48  and  56  (such as packers) may be located above and below the first and second flow control devices  100  and  101 . Sealing devices  48  and  56  thus isolate the annulus region located therebetween from the remainder of the parent well, first lateral branch, and second lateral branch.  
         [0035]    When the operator desires to drain only the first formation  30 , the first flow control device  100  is opened, and the second flow control device  101  is closed. Thus, formation fluid from the second formation  32  flows though openings  38 , into and through second conduit  24 , and up to closed second flow control device  101  which prevents further flow upwards. Formation fluid from the first formation  30  flows through openings  34 , into first conduit  22 , within shroud  152 , through open first flow control device  100 , through junction  26 , and into parent tubing string  28 .  
         [0036]    When the operator desires to drain only the second formation  32 , the second flow control device  101  is opened, and the first flow control device  100  is closed. Thus, formation fluid from the first formation  30  flows though openings  34 , into and through first conduit  22 , and up to closed first flow control device  100  which prevents further flow upwards. Formation fluid from the second formation  32  flows through openings  38 , into second conduit  24 , within shroud  252 , through open second flow control device  101 , through junction  26 , and into parent tubing string  28 .  
         [0037]    When the operator desires to drain both the first and second formations  30  and  32 , the first and second flow control devices  100  and  101  are both opened. Fluid flow from each formation progresses as detailed above until the fluid from both formations reach the junction  26 , at which point the flows become comingled. Thus, commingled flow from the first and second formations  30  and  32  continues within the parent tubing string  28  to the surface of the wellbore  8 .  
         [0038]    When the operator desires to not flow from either first or second formation  30  and  32 , both the first and second flow control devices  100  and  101  are closed. Thus, fluid from the first formation  30  is restricted by first flow control device  100  within first conduit  22 , and fluid from the second formation  32  is restricted by second flow control device  101  within second conduit  24 .  
         [0039]    By selectively opening and/or closing the first and/or second flow control devices  100  and  101 , the operator can independently control the flow from first and second formations  30  and  32 . By selectively choking first or second flow control devices  100  and  101 , the operator can selectively control the rate of flow from first and second formations  30  and  32 .  
         [0040]    Since both first and second flow control devices  100  and  101  are located above the intersection between the parent well  12  and lateral branches  14 ,  16  (and not within the lateral branches), an operator may more easily intervene and workover the devices  100  and  101 . The devices  100  and  101  may thus be replaced, fixed, etc. without having to access either lateral branch  14  or  16 .  
         [0041]    [0041]FIGS. 5 and 6 show a third architecture. A wellbore  8  includes a parent well  12  that may include a vertical section  400  and a horizontal (or inclined) section  402 . The wellbore  8  further includes a lateral branch  404  that intersects the parent well  12 . Parent well  12  intersects a first formation  30  preferably beneath the intersection of the lateral branch  404  and the parent well  12 . Lateral branch  404  intersects a second formation  32 . Formation fluids from the first formation  30  flow into the parent well  12 , and may do so through a sand screen  406  installed within the parent well  12 . Formation fluids from the second formation  33  flow into the lateral branch  404 , and may do so through a sand screen  408  installed within the lateral branch  404 .  
         [0042]    A first sealing device  410 , such as a packer, is installed below the intersection between the parent well  12  and the lateral branch  404 . A second sealing device  412 , such as a packer, is installed above the intersection between the parent well and the lateral branch  404 . Together, first and second sealing devices  410  and  412  isolate the annulus  446  region located therebetween from the remainder of the parent well  12 . A parent tubing string  28  extends within the parent well  12  at least from the first sealing device  410  upwards. The bottom end  29  of the parent tubing string  28  is in fluid communication with the first formation  30 .  
         [0043]    Parent tubing string  28  includes a first flow control device  418  and a second flow control device  420 . First flow control device  418  may be located below second flow control device  420 . As shown in the Figures, first and second flow control devices  418 ,  420  may be located between the first and second sealing devices  410 ,  412 .  
         [0044]    First flow control device  418  selectively provides fluid communication through parent tubing string  28 . When first flow control device  418  is closed, fluid flow is prevented within the parent tubing string  28  across the first flow control device  418 . When first flow control device  418  is open, fluid communication is established through the parent tubing string  28  across the first flow control device  418 . First flow control device  418  may comprise a sliding sleeve valve that includes a shroud  452  and a blocking device  454 , the shroud  452  and blocking device  454  routing fluid from thereunder around the sleeve valve so that the sleeve valve can provide selective flow control of such fluid. The sliding sleeve may also be a variable choke valve that selectively provides different rates of flow therethrough. First flow control device  418  may be controlled from the surface by way of control line  502 , which may be an electric, hydraulic, or fiber optic control line.  
         [0045]    Second flow control device  420  selectively provides fluid communication between the annulus  446 , which is in fluid communication with the lateral branch  404 , and the interior of the parent tubing string  28 . When second flow control device  420  is closed, fluid flow is prevented between the annulus  446  (lateral branch  404 ) and the interior of the parent tubing string  28 . When second flow control device  420  is open, fluid communication is established between the annulus  446  (lateral branch  404 ) and the interior of the parent tubing string  28 . Second flow control device  420  may comprise a sliding sleeve valve which may be a variable choke valve that selectively provides different rates of flow therethrough. Second flow control device  420  may be controlled from the surface by way of control line  500 , which may be an electric, hydraulic, or fiber optic control line.  
         [0046]    When the operator desires to drain only the first formation  30 , the first flow control device  418  is opened, and the second flow control device  420  is closed. Thus, formation fluid from the second formation  32  flows though sand screen  408 , into lateral branch  404 , into annulus  446 , and up to closed second flow control device  420  which prevents flow into parent tubing string  28 . Formation fluid from the first formation  30  flows through sand screen  406 , into parent tubing string  28 , within shroud  452 , through open first flow control device  420 , and continues within parent tubing string  28 .  
         [0047]    When the operator desires to drain only the second formation  32 , the first flow control device  418  is closed, and the second flow control device  420  is opened. Thus, formation fluid from the first formation  30  flows through sand screen  406 , into parent tubing string  28 , and up to closed first flow control device  418  which prevents further flow through parent tubing string  28 . Formation fluid from the second formation  32  flows though sand screen  408 , into lateral branch  404 , into annulus  446 , through open second flow control device  420 , and continues within parent tubing string  28 .  
         [0048]    When the operator desires to drain both the first and second formations  30  and  32 , the first and second flow control devices  418  and  420  are both opened. Fluid flow from each formation progresses as detailed above until the fluid from the second formation  32  reaches the second flow control device  420 . As the second formation fluid passes through open second flow control device  420 , it becomes commingled with the first formation fluid that is flowing through parent tubing string  28 . Thus, commingled flow from the first and second formations  30  and  32  continues within the parent tubing string  28  to the surface of the wellbore  8 .  
         [0049]    When the operator desires to not flow from either first or second formation  30  and  32 , both the first and second flow control devices  418  and  420  are closed. Thus, fluid from the second formation  32  is restricted within the annulus  446  by second flow control device  420 , and fluid from the first formation  30  is restricted by first flow control device  418  within parent tubing string  28  (underneath second flow control device  420 ).  
         [0050]    By selectively opening and/or closing the first and/or second flow control devices  418  and  420 , the operator can independently control the flow from first and second formations  30  and  32 . By selectively choking first or second flow control devices  418  and  420 , the operator can selectively control the rate of flow from first and second formations  30  and  32 .  
         [0051]    Since both first and second flow control devices  418  and  420  are located within parent well  12  (and not within the lateral branches), an operator may more easily intervene and workover the devices  418  and  420 . The devices  418  and  420  may thus be replaced, fixed, etc.  
         [0052]    In each of these architectures, the completion may include various other devices, such as fluid characteristic monitoring devices  504  (pressure, temperature, and/or flow rate—such as the FloWatcher monitoring device shown in the Figure), subsurface safety valve devices  506 , other sealing devices  507  (such as other packers and polished bore receptacle and seal bore connections), expansion joints  508 , liners  510 , liner hangers  512 , casing  514 , multilateral casing junctions  516  (such as disclosed in U.S. Pat. No. 5,944,107, which provides mechanical and sealing integrity to the intersection of the parent and lateral wells), intervention discriminators  518  (which allow selective intervention in downhole conduits), and pressure relief valves  520 . Some of these devices are shown in the Figures. For instance, as shown in the Figures, the parent well  12  may be cased with casing  514  and the lateral branches,  14  and  16 , may be lined with liners  510  secured in place by liner hangers  512 .  
         [0053]    [0053]FIG. 7 shows a more detailed view of one type of flow control device discussed herein, that is a flow control device that includes a sleeve valve, a shroud, and a plug, and which controls fluid flow through/along its connected tubing string. These devices are referred to as “in-line” valves or flow control devices. The device shown in FIG. 7 may be used as flow control device  20 ,  100 ,  101 , and  418 . A plug  54 / 154 / 254 / 454  blocks fluid from continuing its upward travel through a tubing string  9  and diverts it into shroud  52 / 152 / 252 / 452 . Shroud  52 / 152 / 252 / 452  surrounds a sleeve valve  51 / 151 / 252 / 451 , which sleeve is shown in its closed position in FIG. 7 (but open in FIG. 2 for example). When the sleeve is in the closed position, further fluid flow is prevented by the closed sleeve. When the sleeve is in the open position, fluid flows out of the shroud  52 / 152 / 252 / 452 , through ports  55 / 155 / 255 / 455 , and continues upward through tubing string  9 . As previously disclosed, the sleeve valve may also be an adjustable choke providing variable flow rate through the ports and valve.  
         [0054]    It should be noted that although the Figures show lateral branches  14  and  16  (as well as  404  and  402 ) having a generally horizontal direction, such lateral branches may also have any direction (from vertical to horizontal), including the same direction as the parent well  12 , and still fall within the scope of this invention.  
         [0055]    In view of the foregoing it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein.  
         [0056]    As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its spirit or essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.