Patent Publication Number: US-7213654-B2

Title: Apparatus and methods to complete wellbore junctions

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims benefit of U.S. provisional patent application Ser. No. 60/424,455, filed Nov. 7, 2002, which is herein incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to methods for completing wells, such as hydrocarbon and water wells. Particularly, the present invention relates to junctions in multilateral wellbores. More particularly, the invention relates to an apparatus and methods for forming and completing junctions, especially junctions designed for solids exclusion. 
   2. Description of the Related Art 
   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. 
   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 earth formation migrate directly into the wellbore where they are subsequently raised to the surface, typically through an artificial lift system. 
   Junctions between wellbores are commonplace and are useful to reduce costs associated with drilling, to more completely access a formation and to permit multiple formations to be accessed from a single central wellbore. Typically, a lateral wellbore is formed from a central wellbore at some predetermined location with the use of a whipstock or some other type of diverter. The lateral wellbore may be formed along with the central wellbore or it may be formed at a later time when the need arises to access some other formation or some other portion of a formation already being produced. When lateral wellbores are drilled from an existing, cased wellbore, a window is formed in a wall of the casing by milling and then the lateral wellbore is drilled through the window. 
   However the lateral wellbore is formed, the junction between it and the central wellbore becomes a critical part of the well. In some instances, the lateral wellbore is left unlined and a tubular string is inserted therein to transport wellbore fluids. In other cases, a screen type tubular is inserted into the wellbore to collect fluids that migrate from a surrounding formation. In still other cases, the lateral wellbore is lined with a tubular that is centered in place and perforated at some point to permit the introduction of hydrocarbons. In some cases, it is important to hydraulically isolate a lateral wellbore from the central wellbore. Towards this end, hardware has been developed that is insertable into the area of the junction with tubular members that provide connection means for tubulars running up and down the central wellbore and running out into the lateral wellbore. Through the use of packers and seals, the wellbores can be “plumbed” (or “plugged”) in a variety of ways that prevent the co-mingling of fluids between wellbores or portions of the wellbores. A variety of completion options are employed, including the use of a shared production string for delivering production from producing zones in both the primary and lateral wellbores to the surface. Alternatively, separate production tubulars may be used. In any event, it is oftentimes desirable to place sand screens at the actual zones of production in the primary and lateral wellbores. 
   Because of their complexity, these junction-lining devices are very expensive to manufacture and their insertion into a wellbore is complex. More importantly, it is not always necessary or even desirable to utilize a device in a wellbore junction that prevents commingling of fluids. Sometimes, the only need is provide some type of structure that will enhance the strength of the junction while not reducing the internal diameter of the wellbores. For example, junctions that are left completely unlined are more likely to suffer cave in or be adversely affected by pressure spikes from one of the wellbores or from a surrounding formation. Additionally, unlined wellbores have no means to prevent solids from entering the junction and interfering with the production of liquid hydrocarbons. 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 borehole and tubing to obstruct fluid flow. Particles can compact and erode surrounding formations to cause liner and casing failures. In addition, produced sand becomes difficult to handle and dispose of at the surface. Ultimately, open holes carry the risk of complete collapse of the formation into the wellbore. 
   Heretofore, gravel packs have been utilized in wells to preserve the integrity of the formed borehole, and to prevent the production of formation sand. In gravel packing operations, a pack of gravel, e.g., graded sand, is placed in the annulus between a perforated or slotted liner or screen and the walls of the wellbore in the producing interval. The resulting structure provides a barrier to migrating sand from the producing formation while allowing the flow of produced fluids. 
   While gravel packs inhibit the production of sand with formation fluids, they often fail and require replacement due, for example, to the deterioration of the perforated or slotted liner or screen as a result of corrosion or the like. In addition, the initial installation of a gravel pack adds considerable expense to the cost of completing a well. The removal and replacement of a failed gravel pack is even more costly. 
   To better control particle flow from unconsolidated formations, an improved form of well screen has been recently developed. The well screen is known as an expandable sand screen, or “ESS tool.” The ESS is run into the wellbore at the lower end of a liner string and is expanded into engagement with the surrounding formation, thereby obviating the need for a separate gravel pack. In general, the ESS is constructed from three composite layers, including a perforated base pipe, a protective, slotted outer shroud, and an intermediate filter media. The filter media allows hydrocarbons to invade the wellbore, but filters sand and other unwanted particles from entering. Both the base pipe and the outer shroud are expandable, with the woven filter being arranged over the base pipe in sheets that partially cover one another and slide across one another as the sand screen is expanded. 
   The issues related to unlined junctions are most critical during the time a lateral wellbore is being drilled; long before a conventional junction support could be installed. An operator may want to produce fluids from a formation adjacent the wellbore junction and it is therefore desirable to permit fluids to pass into the wellbore at the junction. However, known hardware used to form the junction is comprised of solid metal materials. Thus, production from the formation at the point of the junction itself has heretofore been impossible. Additionally, it is not unusual to produce from a single formation that is intersected by both the central and lateral wellbores. In these cases, there is no reason to prevent co-mingling of the fluids between the wellbores. Finally, there are instances when cemented junctions become brittle or are damaged by pressure differentials. In these instances, some type of support placed in the junction prior to cementing could serve as a reinforcement of the cement and provide a longer lasting more robust junction. 
   A further benefit may be gained from using perforated junction hardware even if production from the junction is not desired. Fluid permeable junction hardware will not have to sustain high external formation pressure or contain high internal pressure which could damage solid junction hardware. 
   Accordingly, a need exists for a method and apparatus for completing a wellbore wherein support is provided for the junction in a multilateral wellbore. Further, a need exists for junction hardware that is not fluid sealed. Still further, a need exists for a junction fabricated from an expandable sand screen so as to prevent sand from entering the production string or otherwise traveling to the surface and being produced. 
   SUMMARY OF THE INVENTION 
   The present invention provides methods and apparatus to complete a junction between two wellbores in a hydrocarbon well. In one aspect of the invention, a junction between a central and lateral wellbore is at least partially lined with a material that prevents solids from migrating into the wellbores but permits fluids to pass therethrough. In another aspect, the junction is lined with a screen-type material to retain strength while the wellbores are completed. In another aspect, the screen-like material provides reinforcement to cement when a junction between wellbores is cemented for hydraulic isolation. 
   In another aspect, central and lateral wellbores are drilled in the earth and thereafter, a string of casing is run into the central wellbore having a section therein which includes a preformed window having screen material covering the window. A pre-inserted whipstock adjacent the window permits a liner to be inserted through the window and into the lateral wellbore. As the liner moves through the window, screen material is extended in a manner, which covers an upper portion of the liner and also the junction between the liner and the window. In a second embodiment of the invention, a portion of a central wellbore adjacent a location for drilling a lateral wellbore is under-reamed to produce an enlarged diameter portion of the wellbore. Thereafter, a string of casing with a section having a preformed window with screen therein is lowered into the wellbore adjacent the under-reamed area. Utilizing the whipstock, a string of liner is inserted through the preformed window and, using an expandable drill, the lateral wellbore is formed and the liner is inserted. After formation of the lateral wellbore, the drill is either removed or remains at the end of the lateral wellbore. 
   In a third embodiment, the screen is run into the central wellbore on a string of tubulars to the junction. The screen is expanded against a wall of the central wellbore. The screen is extended into the lateral wellbore and expanded against the wall of the lateral wellbore. 
   In a fourth embodiment, a first screen is run into the central wellbore on a string of tubulars to the junction and extended or expanded against the wall of the central wellbore. A window is then formed by penetrating the first screen. A second screen is then run through the window into the lateral wellbore and extended or expanded against the wall of the lateral wellbore. The second screen may partially overlap the first screen. 
   In a fifth embodiment, a lateral wellbore is formed from an existing, cased central wellbore after a cylindrical section of screen is disposed across a window is formed by milling the casing wall. Thereafter, as with the previous embodiments of the invention, a liner is run-in to the lateral wellbore in a manner that extends the screen material along the outer portion of the liner, causing the screen material to cover the interface between the liner and the window. 
   In a sixth embodiment, the screen is placed into the junction according any previous embodiments and cemented into place. 
   In a seventh embodiment, a screen is run to the junction on an expandable tubular. The screen is expanded into the lateral wellbore as with previous embodiments. The tubular is then expanded thereby fixing the screen and tubular in the wellbore. 
   In an eighth embodiment, an expandable junction component is run into a junction and expanded into place. In one aspect, the component is constructed of a multi-layered sand screen material. In a second aspect, the component comprises a pre-formed central wellbore access port and is only partially expandable. 
   In a ninth embodiment, an expandable junction component is run into a lateral wellbore. In one aspect, the junction component is run in with expandable production tubing that may be sand screen. The junction component may just be one end of the expandable production tubing. The junction component and tubing are then expanded against the wall of the lateral wellbore. In a second aspect, the junction component is expanded into place and then conventional production tubing is run into the lateral wellbore and coupled to the junction component. In either aspect, a central wellbore access port may then be milled into the junction component. 
   In a tenth embodiment, a lateral wellbore is formed and lined according to the first aspect of the ninth embodiment. If necessary, a central wellbore access port is milled into the junction component. A production string has been lowered into the central wellbore with a packer. In one aspect, a sump pump is provided in the production string. Production may then be from the central wellbore while isolating the junction and the lateral wellbore. In a similar second aspect, the pump is replaced by a sleeve valve. Production may then be from a selection between just the central wellbore and commingled production from the central and lateral wellbores and the junction. In a third aspect, a production string is lowered into the central wellbore to a point just above the junction. Two sub-strings extend from the production string, one into the central wellbore below the junction and one into the lateral wellbore past the junction. The lateral sub-string is sealingly coupled to the expanded tubing already in place. Production may then be commingled from the central and lateral wellbores while isolating the junction. In a similar fourth aspect, each sub-string is a complete string to the surface. Production may then be separate from the lateral and central wellbores while isolating the junction. Alternatively, any of the previous aspects may be configured to add another production path by removing the packer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. 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. 
       FIG. 1  is a section view showing a central wellbore with a lateral wellbore extending therefrom. 
       FIG. 2  is a section view of the central and lateral wellbores of  FIG. 1  showing a casing with a screen section and a preformed window disposed in the central wellbore adjacent the lateral wellbore. 
       FIGS. 3A–6B  are schematic views of the screen portion of the casing illustrating the manner in which screen material in the window is folded and inserted into the casing prior to run-in. 
       FIG. 7  is a section view of the central and lateral wellbores illustrating the interior of the screen section and showing a preinstalled whipstock disposed therein. 
       FIG. 8  is a section view of the central and lateral wellbores illustrating a liner partially inserted into the lateral wellbore via the whipstock. 
       FIGS. 9A , B– 11 A, B are sketches illustrating the manner in which the screen material in the window interacts with the liner to extend into the lateral wellbore, covering the external surface of the liner. 
       FIG. 12  is a partial section view illustrating the liner partially installed through the window of the casing. 
       FIG. 13  is an elevation view showing the portion of the liner extending from the window completely covered with screen and the screen interface between the liner and the casing window. 
       FIG. 14  is a section view of a wellbore including a central wellbore having an enlarged diameter portion. 
       FIG. 15  is a partial section view of the wellbore of  FIG. 14  illustrating a string of casing inserted in the wellbore with a preformed window formed in the casing and screen material wrapped around the casing at the location of the window. 
       FIG. 16  is a partial section view of the wellbore after a string of liner has been extended through the casing window. 
       FIG. 17  is a partial section view illustrating the liner string extending through the window and showing the interface between the liner and the casing window completely covered with screen material.  FIG. 17  also shows an expandable drill bit forming a lateral wellbore. 
       FIG. 18  is a partial section view illustrating the lateral wellbore completely formed and the junction between the liner and the casing window completely covered with the screen material. 
       FIG. 19  is an elevation view of a central wellbore and a lateral wellbore illustrating the use of a screen portion to line and strengthen a junction formed between the two wellbores. 
       FIGS. 20A–20D  illustrate a method for inserting screen portions into a central and lateral wellbores to protect and strengthen the wellbores during drilling operation. 
       FIGS. 21A–21C  illustrate another embodiment of the invention wherein a junction between a central and lateral wellbores is reinforced with screen material prior to forming the lateral wellbore. 
       FIG. 22  illustrates the use of a screen portion to reinforce cement that is used in and around a wellbore junction. 
       FIGS. 23–29  illustrate the steps of a method wherein the screen is installed on an expandable tubular which is subsequently expanded to fix the screen into the junction. 
       FIG. 30  presents three cross-sectional views of a multilateral wellbore junction. Each of  FIGS. 30A–30C  presents a different expandable junction component that has been installed at the intersection of the primary and lateral wellbores.  FIG. 30D  illustrates different perforation configurations that may be employed in the sand screen junction components. 
       FIG. 31  presents four cross-sectional views of a multilateral wellbore junction.  FIGS. 31A and 31B  illustrate completion of the lateral wellbore with expandable production tubing.  FIGS. 31C and 31D  illustrate completion of the lateral wellbore with conventional production tubing. 
       FIG. 32  presents four cross-sectional views of a multilateral wellbore junction.  FIG. 32A  illustrates pumping from the central wellbore while isolating the lateral wellbore with mono-bore completion to the surface.  FIGS. 32B  illustrates selective production between central wellbore production and commingled central wellbore and lateral wellbore production, with mono-bore completion to the surface.  FIG. 32C  illustrates commingled central wellbore and lateral wellbore production while isolating the junction, with mono-bore completion to the surface.  FIG. 32D  illustrates simultaneous separate central wellbore and lateral wellbore production while isolating the junction, with dual-bore completion to the surface. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENT 
     FIG. 1  is a section view showing a central wellbore  100  with a lateral wellbore  200  extending therefrom. Typically, the central wellbore  100  is formed and thereafter, using some whipstock or other diverter that is temporarily placed in the central wellbore  100 , the lateral wellbore  200  is formed to more fully access a formation or to access a different formation adjacent the central wellbore  100 . In this specification, the interface between the central wellbore and the lateral wellbore is considered a wellbore junction and that junction  300  is generally illustrated in  FIG. 1 . 
     FIG. 2  is a section view illustrating the wellbore  100  with a string of casing  110  disposed therein. In the case of  FIG. 2 , the string of casing  110  includes a section, which includes screen material  120  disposed therein and held at each end by upper and lower rings  115 ,  118 . Preformed in a wall of the casing  110  at junction  300  is a window  305  visible in profile in  FIG. 2 . The purpose of the screen material  120  disposed within the casing  110  is to insure that screen material  120  covers the preformed window  305  in order to provide means to exclude solids between the lateral wellbore  200  and the casing window  305 , as will be discussed herein. Typically, the screen  120  is disposed within the casing  110  after the preformed window  305  has been formed and the screen  120  is then held tightly to the casing by the rings  115 ,  118 . The screen material  120  is typically composed of at least one and more multiple layers of metallic, woven mesh and is sized in order to prevent the inflow of solid particles. In some instances, where the screen material  120  might be stretched, the material  120  may include a series of scaled filter sheets which are layered and include the compability of moving laterally in relation to each other without any significant loss of filtering capability. The outer surface of the screen material  120  may include a protective layer, wherein the filter and protective layer are sintered together. This results in a robust screen,  120  wherein the sieve size does not change significantly during or after deformation by stretching. After running the string of casing  110  into the central wellbore  100  and locating the window  305  adjacent the lateral wellbore  200 , the string of casing  110  is typically held in the central wellbore  100  by some type of hanging means or by a separate string of tubulars extending to the surface of the well (not shown). 
   Alternatively, the screen  120  may be constructed from three layers, including a perforated base pipe, a protective, slotted outer shroud, and an intermediate filter media. The screen  120  would have rigidity like that of pipe and serve as the casing proximate the junction. The rings  115 ,  118  would then merely serve to couple the screen  120  to the casing  110 . The window  305  would then be pre-formed in a wall of the multi-layered screen  120  instead of the casing  110 . This multi-layered screen may also be expandable. 
   In order to insure that the interface between a string of liner and the window  305  is completely covered with screen  120 , additional screen material may be provided in the area of the preformed window  305 . The additional screen material will form a type of “pant-leg”  250  for a liner is illustrated in  FIGS. 3A–6B . The pant-leg  250  may also comprise three layers. The pant-leg  250  will be folded and housed within the casing  110  at the surface prior to run-in.  FIGS. 3A–6B  illustrate that portion of the string of casing  110  that includes the screen material  120  and the preformed window  305 . For clarity, the screen material  120  within the casing  110  is not illustrated but extends between the upper and lower rings  115 ,  118  as shown in  FIG. 2 . In addition to the screen material  120  within the casing  110 , the additional screen material or pant-leg  250  is illustrated in  FIG. 3A .  FIG. 3B  is a view of  3 A taken from the bottom, illustrating the pant-leg  250  having a circular shape prior to installation into the casing  110 .  FIG. 3A  illustrates the pant-leg  250  fully extended as it will appear in the lateral wellbore after the string of liner inserted through the window  305 . 
   In order to prepare the pant-leg  250  portion of the screen material  120  for insertion into casing  110 , the material is first folded upwards into a folding portion  255  as illustrated by the dotted line portion of the pant-leg  250  visible in  FIG. 4A . After the folded portion  255  is formed, pant-leg  250  is folded, the bottom view of the assembly visible in  FIG. 4B  illustrates the relative proximity of the bottom of the pant-leg  250  to the casing  110 .  FIG. 5A  illustrates additional manipulation of the cuff portion  255  of the pant-leg  250 . Specifically, as illustrated in  FIG. 5B , a bottom view of the assembly, the folded portion  255  is shaped into a crescent shape  260  as a center portion is urged inward in relation to the outer edges. Thereafter, the outer edges of the crescent shape  260  are manipulated inwards to a point where the pant-leg  250  is completely housed in the casing  110 , as shown in  FIG. 6A  and  FIG. 6B , a bottom view of the assembly illustrating the relative position of the screen material  120  relative to the casing  110 . 
   Not shown in  FIGS. 3A–6B  is a whipstock which may be disposed in the casing  110  adjacent the preformed window  305  at the surface prior to folding the pant-leg  250 . The whipstock includes a cut-out portion  275  (see  FIG. 7 ) constructed and arranged to hold the folded portion  255  of the screen as the casing  110  is run into the wellbore. Specifically, the folded portion  255  is housed in the cut-out in order to avoid interfering with a string of liner as it run down the whipstock and through the casing window  305  as will be described herein. 
     FIG. 7  is a partial section view of the central and lateral wellbores  100 ,  200  illustrating that section of casing  110  in the central wellbore  100  which includes the preformed window  305  and shows especially a whipstock  270  which is inserted in the casing  110  prior to run into the central wellbore  100  as well as a cut-out portion  275  of the whipstock which includes the folded portion  255  of the pant-leg  250 . As discussed previously, the cut-out portion  275  serves as a housing for the folded portion  255  to prevent the folded portion  255  from interfering with use of the whipstock  270  when a string of liner is inserted into the lateral wellbore  200 . Also visible in  FIG. 7  is an anchor assembly  280  which is used to temporarily anchor the whipstock  270  in the casing  110  while a liner is run into the lateral wellbore  200 . 
     FIG. 8  is a partial section view similar to  FIG. 7  but illustrating a string of liner  310  partially run along an inclined surface  271  of the whipstock  270  and having made initial contact with the screen material  120 . Visible specifically in  FIG. 8  is the folded portion  255  of the pant-leg  250  as it is partially urged away from the cut-out portion  275  of the whipstock  270  by a leading edge  306  of the string of liner. 
     FIGS. 9A–11B  illustrate the movement of the pant-leg  250  and the folded  255  portion of the screen as it is urged into an extended position in the lateral wellbore by the liner as the liner extends through the preformed casing window  305  and into the lateral wellbore.  FIG. 9A and 9B  correspond to  FIG. 8 , showing the folded portion  255  of the pant-leg  250  partially pushed through the window  305  formed in the casing  110 . As shown in  FIG. 9B , the folded portion  255  is in the crescent shape  260  as it begins to unfold. 
   In  FIGS. 10A , B, the pant-leg portion  250  is completely extended through the window  305  due to the insertion of the liner string and only the folded portion  255  remains. Finally,  FIGS. 11A and 11B  illustrate the pant-leg portion  250  completely extended as it would appear once the liner string has been completely inserted into the lateral wellbore. 
     FIG. 12  corresponds basically to  FIGS. 10A and 10B  and illustrates the pant-leg portion  250  of the screen extended out into the lateral wellbore  200  but with the folded portion  255  still remaining folded within. The whipstock is no longer visible in the central wellbore  100  and typically would have been removed. In  FIG. 13 , an elevation view of the central  100  and lateral  200  wellbores the pant-leg  250  is shown fully extended as it appears after the string of liner  310  has been completely inserted. Visible specifically in  FIG. 13  is the interface or junction  300  between casing window  305  and the string of liner  310  in the lateral wellbore  200 . As is apparent from  FIG. 13 , the junction  300  is now completely sealed with the screen material  120  and while fluids may pass through, the passage of solids is effectively blocked depending upon the characteristics of the screen material  120 . 
   In another embodiment of the invention, a lateral wellbore is formed through a window having a screen portion like the one previously described.  FIG. 14  illustrates a central wellbore  100  with an enlarged diameter portion  105  formed therein. Typically, the larger diameter portion is formed with an under reamer (not shown) that includes some type of extendable blade members that can be selectively extended to enlarge the diameter of a section of wellbore. The purpose of the enlarged diameter portion  105 , as will be explained herein, is to permit a liner string (not shown) to be at least partially inserted through a casing window (not shown) prior to the formation of a lateral wellbore.  FIG. 15  is a partial section view of the wellbore of  FIG. 14  showing the string of casing  110  installed into the central wellbore  100  and having the preformed window  305  in a wall thereof. In  FIG. 15  the window  305  is visible in profile. Also included in the casing string  110  adjacent the window  305  is a pre-located whipstock (not shown) that will be used to run a string of liner (not shown) through the window  305 . Additionally, as with the previous embodiment, the screen portion  120  is disposed within the casing  110  and held by rings  115 ,  118  at an upper and lower end. As with the previous embodiment, also included is a pant leg portion (not visible) of the screen  120  that is initially housed in a cut-out portion of the whipstock (see  FIGS. 3A–6B ). 
     FIG. 16  is a section view that shows the liner string  310  being inserted through the window  305  and into the enlarged diameter area  105  of the wellbore. As with the previous embodiments, the movement of the liner string  310  along an inclined surface of the whipstock causes a folded portion of the pant leg to straighten out and the pant leg to be carried towards that portion of the wellbore from which the lateral wellbore will extend. 
     FIG. 17  is a partial section view showing the liner  310  extended completely through the window  305  to a point wherein the pant leg portion  250  of the screen is completely extended and the interface or junction  300  between the liner  310  and the window  305  formed in the casing  110  wall is completely covered with the screen material  120 . At a lower end of the liner  310  is a separate string of drilling tubulars  320  and a bit  325  disposed at the end thereof. In the preferred embodiment, the bit  325  is initially fixed and housed within the end of the liner string  310 . After the end of the liner  310  has been inserted through the casing window  305  and into the enlarged diameter portion  105  of the central wellbore  100 , the bit  325  is remotely disconnected from the liner  310  and can be moved axially with respect to the liner  310 . Additionally, with the use of a mud motor (not shown) or other device that can transfer fluid flow to rotational movement, the drill can be rotated to form the lateral wellbore. Also, in the preferred embodiment, the bit  325  is an expandable bit with extendable portions that can be selectively and remotely activated to enlarge the diameter of the bit  325  to a size greater than the outer diameter of the liner  310 . 
     FIG. 18  is a partial section view showing the lateral wellbore  200  completely formed and the interface or junction  300  between the liner  310  and the casing window  305  completely covered with the screen material  120 . Typically, the whipstock in the casing  110  is removed after formation of the lateral wellbore  200  and the expandable bit (not shown) is left in the end of the newly formed lateral wellbore  200 . 
     FIG. 19  is an elevation view of a central wellbore  100  and a lateral wellbore  200  illustrating the use of a screen portion  120  to line and strengthen a junction  300  formed between the two wellbores  100 ,  200 . The screen portion  120  would typically be run-in into the wellbore  100  on a string of tubulars (not shown) and then, a central portion  410  of the screen  120  expanded against a wall of the central wellbore  100  and a lateral portion  415  extended and expanded against a wall of the lateral wellbore  200 . Due to the relatively stiff nature of the screen material  120 , it can easily be transferred downhole in a collapsed or folded orientation and subsequently extended and expanded to take the shape illustrated in  FIG. 19 . In  FIG. 19 , the central wellbore  100  also includes a casing  110  which enters an upper end of the central portion  410  of the screen  120  and exits a lower end thereof permitting the central wellbore  100  to be utilized below the reinforced junction  300 . Alternatively, or in addition to the casing  110  running vertical through the screen portion, a string of liner (not shown) could extend through the lateral portion  415  and into the lateral wellbore  200  therebelow. 
     FIGS. 20A–20D  illustrate a method for inserting screen portions  120  into a central  100  and lateral  200  wellbores in order to protect and strengthen the wellbores  100 ,  200  during drilling.  FIG. 20A  shows the central wellbore  100  with the lateral wellbore  200  extending therefrom. Disposed along the walls of the central wellbore  100  is a tubular screen portion  120  which is run-in into the wellbore  100  and extended or expanded therein to contact the wellbore  100  walls.  FIG. 20B  illustrates the central and lateral wellbores  100 ,  200  of  FIG. 20A  with the screen portion  120  having been penetrated and a window  305  formed therein to permit communication between the central and lateral wellbores  100 ,  200 .  FIG. 20C  illustrates a second tube-shape screen portion  420  which has been run into the lateral wellbore  200 , inserted through the window  305  formed in the first screen portion  120  and then extended or expanded against the walls of the lateral wellbore  200 . Finally,  FIG. 20D  illustrates the wellbore junction  300  completely lined and strengthened with the screen material  120 ,  420 . The second tubular shape screen member  420  has been deformed whereby a portion of it extending into the central wellbore  100  has been folded down to further line the central wellbore  100  below the window  305 . In this manner, using separate tubular screen members  120 ,  420  any portion of a wellbore junction  300  can be selectively lined and strengthened. Additionally, while the illustration shows only one lateral wellbore  200 , it will be understood that any junction can be reinforced, even one having multiple lateral wellbores extending therefrom. 
     FIGS. 21A–21C  illustrate another embodiment of the invention wherein a junction  300  between a central and lateral wellbores  100 ,  200  is reinforced with screen material  120  prior to forming the lateral wellbore  200 .  FIG. 21A  illustrates the central wellbore  100  having casing  110  disposed therein. Located in the casing  110  is a whipstock  270  having an inclined surface  271  and, thereabove, a milling bit  325  as would be run into the wellbore  100  and used to form a window  305  in a wall of the casing  110 . Milling bits  325  are well known in the art and typically are used to form casing windows and thereafter they are removed from the wellbore and replaced with a more conventional drill bit which forms the lateral wellbore  200 .  FIG. 21B  illustrates the central wellbore  100  after window  305  has been formed in the wall of the casing  110  by the milling bit which has been removed. As illustrated in  FIG. 21B , the formation of the casing window  305  necessarily results in an extension  425  which is formed in the earth outwards of the window  305 .  FIG. 21C  illustrates the central wellbore  100 , the casing window  305  and the extension  425  after the junction  300  between the wellbore  100  and extension  425  has been reinforced with screen material  120 . As with previous embodiments, the screen material  120  may be run into and inserted at the junction  305  in a variety of ways. For example, a tubular shape of the screen can be run into the wellbore  100  in a collapsed condition and thereafter urged through the casing window by a bent sub or a diverting device (not shown). Thereafter, using a cone-shaped object (not shown) run-in on a string of tubulars (not shown), the screen  120  can be expanded into contact with the walls of the central wellbore  100 , and the extension  425 . 
   In addition to those methods described, the screen portion  120  may can be expanded using an expander tool (i.e., see  FIGS. 26–29 ) which includes at least one radially extendable member disposed on a body and extendable through fluid pressure delivered to the body through a string of tubulars having pressurized fluid therein. Expander tools are well known in the art and an example of one is taught in U.S. Pat. No. 6,425,444, assigned to the same owner as the present application and that patent is incorporated herein in its entirety. 
     FIG. 22  illustrates a central wellbore  100  having a lateral wellbore  200  extending therefrom and specifically teaches the use of the screen portion  120  of the invention to reinforce cement  430  that is used in and around a wellbore junction  300 . In  FIG. 22  the junction  300  between the central and lateral wellbores  100 ,  200  has been strengthened through the use of at least one screen portion  120  as described with reference to other embodiments of the invention. Thereafter, tubular strings (not shown) in each wellbore  100 ,  200  are cemented in place using cementing techniques well known in the art. Rather than leaving a layer of fragile cement  430  between a tubular member and the earthen walls of the wellbores  100 ,  200 , the screen  120  is at least partially permeated by the cement  430  and serves as a reinforcing member to protect the cement  430  from shock and breakage, especially due to pressure differentials. 
   In another embodiment of the invention, a screen portion is utilized in a junction of wellbore which is created from an existing, cased central wellbore.  FIG. 23  is a section view illustrating a central wellbore  500  with casing  510  cemented therein.  FIG. 24  is a section view of the wellbore after a window  520  has been formed in a wall of the casing  510 . Visible in  FIG. 24  is a whipstock  530  held in place by an anchor  535  and having an inclined portion  540  which is utilized by a mill and drill bit which forms the casing window and a lateral wellbore  550 .  FIG. 25  is a section view of the wellbore illustrating the junction  560  between the central and lateral wellbores. The apparatus used in forming the casing window  520  and the lateral wellbore  550  has been removed and a tubular member  565 , housing various components, has been lowered into the wellbore. The tubular member includes a window  570  formed therein as well as an upper and lower rings  580 ,  585  used to retain a screen portion (not shown) around the tubular member  565 .  FIG. 26  is a section view of the tubular member  565  showing the various components therein. From the top of  FIG. 26  towards the bottom, the components include a run-in string  590 , an expander tool  600 , a torque anchor  605  disposed therebelow and a cone member  610  disposed below the torque anchor. Disposed further downwards in the tubular member is a whipstock  615  having a cut-out portion  620  formed therein constructed and arranged to house a pant-leg portion  625  of screen. Disposed below the whipstock is a packer  630 . The screen portion, including the pant-leg portion  625  is arranged in the tubular member and within the cut-out portion  620  of the whipstock in a similar fashion as discussed with previous embodiments. The tubular member  565  may be replaced by the multi-layered, expandable screen discussed above. 
     FIG. 27  is a section view of the apparatus illustrating the cone member  610  having been extended downwards along an inclined surface  635  of the whipstock to a location whereby it interferes and upsets the pant-leg portion  625  of the screen. As shown in  FIG. 27 , the cone  610  is extended downward and has urged a folded portion of the pant-leg  625  outwards towards the lateral wellbore  550 . The cone moves downward on a relatively small diameter pipe  640  which is movable axially independently of the other components. As the screen portion is manipulated, the tubular member and other components are held in the wellbore by torque anchor  605  which includes radially extendable gripping portions  606  disposed therearound. 
     FIG. 28  illustrates the pant-leg portion  625  of the screen completely unfolded and extended out into lateral wellbore  550 . With the pant-leg portion completely extended outwards, the expander tool can be activated and radially extendable rollers thereupon extend outward to push walls of the tubular portion into gripping contact with the casing therearound. In this manner, and with some axially movement of the expander tool, the assembly including the tubular member and the components therein becomes fixed in the wellbore. Thereafter, with the packer  630  disengaged and the torque anchor and expander tool deactivated, the assembly, including the whipstock  615  can be removed from the wellbore. Alternatively, the expander tool can be moved downwards to a position below the window and reactivated, thereby sealing an annular area formed between the outer surface of the tubular member and the casing wall. In this manner, any flow of fluid is prevented from passing through the wellbore without coming into contact with the screen portion. 
     FIG. 29  illustrates the components removed leaving only the tubular portion  565  with its preformed window  520  and the screen therein and a string of liner  650  extending through the window and into the lateral wellbore  550 . A whipstock used to insert the liner through the casing window has also been removed. As is visible in  FIG. 29 , the junction  560  between the liner and the casing window is substantially covered with the screen material and any solids can be filtered while fluids can pass through the screen material. Expanded portions  566 ,  567  seal the annular area between the casing and the tubular portion  565 . 
     FIGS. 30A–C  present three cross-sectional views of a multilateral wellbore. In one embodiment, a lateral wellbore junction  905  has been formed off of a cased  902  and cemented  901  primary wellbore  900 . In order to accomplish this, a whipstock (not shown), a deflector  910 , and an anchor  915  are lowered into the primary wellbore  900 . The whipstock is properly oriented and located using conventional MWD, gyro, pipe tally, or radioactive tags. The anchor  915  is set. A window is milled/drilled through the casing  902  and the cement  901 , using the whipstock (not shown) as a guide, and the drilling is continued until a junction  905  is formed. Since expandable junctions  920  will be installed, the wellbore junction  905  may be under-reamed, such as with a bi-center or expandable bit, resulting in an inside diameter near that of the central wellbore  900 . The whipstock (not shown) is removed and replaced by a deflector stem  912 . The deflector stem  912  and deflector device  910  may comprise a mating orientation feature (not shown), such as a key and keyway, for properly orientating the deflector stem into the deflector device. The deflector device  910  and the anchor  915  may comprise a flow port (not shown). The anchor  915  may further comprise packing means or may be a separate anchor and packer. Once the deflector stem  912  is set, an expandable (or partially expandable, see below) junction component  920  (unexpanded) is lowered through the primary wellbore, along the deflector stem  912 , to the junction  905 . The junction component  920  is then expanded against the walls of the primary wellbore  900  and the junction  905  using an expander tool (i.e., see  FIGS. 26–28 ). In each instance, the expandable components  920  are set and expanded before completing the lateral wellbore to prevent damage of the junction  905  due to subsequent drilling of the lateral wellbore. 
   Depicted in  FIG. 30A  is an expandable sand screen junction component  920 , such as Weatherford&#39;s ESS®. Three layers of the sand screen  920  are shown, representing a perforated base pipe  920   c , a protective outer shroud  920   a , and an intermediate filter media  920   b . Slots are seen within the base pipe  920   c  and the shroud  920   a . In  FIG. 30 , the sand screen  920  is shown in its expanded position. In this manner, the sand screen  920  is expanded downhole against the casing  902  and the junction  905  in order to preserve the integrity of the junction  905  during subsequent drilling and production. 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. 
   Illustrated in  FIG. 30B  is a solid expandable junction component  920 . Depicted in  FIG. 30C  is a partially expandable sand screen junction component  920  with a preformed central wellbore access port  922 . In  FIG. 30C , note that the component  920  is shown only partially expanded because the preformed port  922  may not allow expansion of the component over the portion it covers. A mating feature, such as a hook  921 , is provided on the partially expandable junction component to retain it inside the junction during expansion and to properly locate and orient it at the junction. The mating feature may be disposed on the other junction components. The hook  921  may be permanent, temporary, or shearable. Other means can be used to orient and locate the junction components, such as conventional MWD, gyro, pipe tally, or radioactive tags. The partially expandable component  920  may also be solid.  FIG. 30D  illustrates various perforation configurations that may be formed in the sand screen junction components. As discussed earlier, the sand screen junction components will allow production at the junction  905  while filtering particulate matter out of the production fluid. The sand screen components shown in  FIGS. 30A and 30C  need not be multi-layered. 
   FIGS.  31 A–B and  31 C–D provides two alternate completion methods to that displayed in  FIGS. 30A–C . In this embodiment, a lateral wellbore  932  has been formed off of a cased  902  and cemented  901  primary wellbore  900 . Contrary to the earlier described method, the entire lateral wellbore  932  is drilled before installation of the junction component  920 . In  FIG. 31A , the junction component  920  is installed with expandable sand screen production tubing  935  extending through lateral wellbore  932 . The component  920  and the production tubing  935  are expanded together in one step. Expansion of the sand screens  920  and  935  obviates the need for a gravel pack, and allows for a larger i.d. within the junction  905 . The junction component  920  does not have to be separate from the production tubing  935 ; it may just comprise the portion of the production tubing  935  located in the vicinity of the junction  905 . The production tubing  935  may be sand screen, solid, or a combination of both. Any of the junction components  920  displayed in  FIGS. 30A–C  may be used. For example, if there is no reservoir in the vicinity of the junction  905  or if there is a reservoir containing undesirable fluid, i.e. water, a solid junction component  920  would be preferable so as to isolate the junction. This would prevent escape of production fluid into the junction  905  in the former case and prevent commingling of an undesirable fluid in the latter case. If production equipment is desired in the central wellbore  900  below the junction (discussed below), the junction component  920  must be milled out to create a central wellbore access port  922  as shown in  FIG. 31B . The deflector stem  912  may also be retrieved after milling as shown in  FIG. 31B . If the solid junction component  920  is used, it must be milled to allow production from the central wellbore  900  below the junction  905 . 
   In  FIG. 31C , the expandable sand screen junction component  920  is installed before any production tubing  937 . The production tubing  937  is then lowered through the expandable junction component  920  and coupled to the end of the junction component proximate the lateral wellbore  932  by a packer  965 . The packer  965  may be part of a liner hanger. In this embodiment, the production tubing  937  is conventional (non-expandable) and slotted. This configuration is preferable for the case where a desirable reservoir (not shown) extends the length of the junction  905  and lateral wellbore  932 , since the junction is not isolated from the lateral wellbore. The production tubing  937  may be solid when installed and later perforated by known means, such as perfing, chemical cut, mechanical cut, milling, drilling, explosives, dissolving, piercing, forming, or punching. Again, if additional production equipment is desired in the central wellbore  900  below the junction  905 , then the slotted junction component  920  must be milled as shown in  FIG. 31D . Again, the deflector stem  912  has been retrieved from the deflector device  910  as shown in  FIG. 31D . Of course, the lateral wellbore  932  may be left open and no production tubing provided, if desired. Again, any of the junction components  920  displayed in  FIGS. 30A–C  may be used. 
   Either completion method, discussed with reference to  FIGS. 31A–B  or  FIGS. 31C–D , may comprise the extra steps of first drilling the junction  905 , installing the junction component  920 , and then drilling the lateral wellbore  932  to completion as discussed above with reference to  FIG. 30 . 
     FIGS. 32A–D  provide four alternate completion methods for a multilateral wellbore. In each instance, a lateral wellbore  932  has been formed off of a cased  902  and cemented  901  primary wellbore  900 . A junction component  920  is shown in each view. Further, in each view, the central wellbore access port  922  has been formed (or pre-formed) in the bottom of the junction component in order to provide access to the primary wellbore  900  below the junction  905 . The junction  905  and lateral wellbore  932  configurations shown in  FIG. 32  have been completed according to the methods discussed above with reference to  FIGS. 31A and 31B . These configurations could also be completed with the methods discussed above with reference to  FIGS. 30 ,  31 C, and  31 D. 
   Shown in  FIGS. 32A and 32B , a single production string  950  comprising a packer  945  is run from the surface, through the junction  905 , and to the deflector  910  and anchor  915 . The packer  945  is set above the junction  905  in the central wellbore  900 . In  FIG. 32A , a sump pump  940  having a control line  942  is disposed in the production string  950  for production in the central wellbore  900  below the junction  905 . The lateral bore  932  and junction  905  are isolated by the packer  945 , deflector device  910 , and anchor/packer  915 , thus prohibiting any production from them. In  FIG. 32B , a remotely operated sleeve valve  955  having the control line  942  is included in the production string  950  at or near the location of the junction  905 . This enables an operator to select production from the central wellbore  900  or commingled production from the central wellbore, junction  905 , and lateral wellbore  932 . The sleeve valve may also be used in the configuration shown in  FIG. 32A  to allow for production from the junction  905  and the lateral wellbore  932 . 
   The control line  942  runs within an encapsulation from the surface (not shown) along the production string  950 . The encapsulation  12  is secured to the production string  950  by clamps (not shown). The clamps are typically secured to the production string  950  approximately every ten meters. The encapsulation  12  passes through the packer  945  (or utilized hanging apparatus), and extends downward to the top of the sand screen  920 . The control line  942  enters a recess (not shown) in the outer diameter of the junction component  920 . Arrangements for the recess are described more fully in the pending application entitled “Profiled Recess for Instrumented Expandable Components,” having S/N No. 09/964,034, which is incorporated herein in its entirety, by reference. However, the control line  942  may also be housed in a specially profiled encapsulation around the component  920  which contains arcuate walls. Arrangements for the encapsulation are described more fully in the pending application entitled “Profiled Encapsulation for Use With Expandable Sand Screen,” having S/N No. 09/964,160, which is also incorporated herein in its entirety, by reference. 
   Illustrated in  FIGS. 32C and 32D , production tubing  937  having the packer  967  is lowered into the lateral wellbore  932  and the packer  967  is set against the expandable tubing  935 . This configuration will allow production string or sub-string  960  to be coupled with tubing  937 . Referring to  FIG. 35C , the production string  950 , comprising the packer  945  and sub-strings  952  and  960 , is run from the surface. The central sub-string  952  extends from the packer  945 , which is again placed in the production string  950  above the junction  905 , through the port  922  in the junction, and to the anchor  915  and deflector  910 . The lateral production sub-string  960  extends from the packer  945 , through the junction  905 , to the production tubing  937 . The result is commingled production from both the central wellbore  900  and the lateral wellbore  932  while completely isolating the junction  905  with the packers  945  and  965  and the anchor/packer  915 . The configuration shown in  FIG. 32D  is similar to the one shown in  FIG. 32C  except that two production strings  952  and  960  coupled by packer  945  are run from the surface. The result is simultaneous separate production from the central wellbore  900  and lateral wellbore  932 . Referring to  FIGS. 32C and 32D , optionally, the sand screen junction component  920  could be replaced by solid expandable tubing thereby removing the need for string/sub-string  960 , tubing  937 , and the packer  965 . 
   In any of the configurations illustrated in  FIG. 32 , the packer may be removed (replaced by just a pipe junction) utilizing the casing  902  for another production path. 
   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. For example, the junction component could have added features to act as a bridging member to solids, sands, fluid, etc. to provide a natural seal. These may include swellable elastomers, epoxys, brushes, mesh materials, fibrous materials, foam, etc. Further, the junction component could be combined with the screen, disclosed in earlier embodiments, as a further barrier to solids, etc. Further, a cementing step may be added to the completion of the lateral wellbore. Also, the junction component may be carried in a retrievable deflector on the end of a liner shoe during any installation.