Patent Abstract:
An improved method for completing wells, such as hydrocarbon wells, is provided. In one aspect, methods are provided for deploying an expandable tubular, such as an expandable sand screen, in a hydrocarbon well. According to methods of the present invention, a sand screen is lowered into a wellbore. Thereafter, cement is injected into the wellbore so as to place a column of cement in the annular region between the tubular and the surrounding formation. The cement is then treated so as to imbue greater permeability and/or porosity characteristics. The cement serves to reinforce the sand screen, providing it with both improved physical strength and improved sand filtering ability. At the same time, the sand screen serves to reinforce and strengthen the cement sheath placed in the wellbore.

Full Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to methods for completing wells, such as hydrocarbon and water wells. More specifically, the present invention provides methods for deploying an expandable tubular in a hydrocarbon well. More particularly still, methods are provided for placing an expandable perforated tubular, such as a sand screen, within a wellbore having a permeable cement.  
           [0003]    2. Description of Related Art  
           [0004]    Hydrocarbon wells are typically formed with a central wellbore that is supported by steel casing. The steel casing lines the borehole formed in the earth during the drilling process. This creates an annular area between the casing and the borehole, which is filled with cement to further support and form the wellbore.  
           [0005]    Some wells are produced by perforating the casing of the wellbore at selected depths where hydrocarbons are found. Hydrocarbons migrate from the formation, through the perforations, and into the cased wellbore. In some instances, a lower portion of a wellbore is left open, that is, it is not lined with casing. This is known as an open hole completion. In that instance, hydrocarbons in an adjacent earth formation migrate directly into the wellbore where they are subsequently raised to the surface, typically through an artificial lift system.  
           [0006]    Open hole completions carry the potential of higher production than cased hole completions. Open hole completions are frequently utilized in connection with horizontally drilled boreholes. However, open hole completions present various risks concerning the integrity of the open wellbore. In that respect, an open hole leaves aggregate material, including sand, free to invade the wellbore. Sand production can result in premature failure of artificial lift and other downhole and surface equipment. Sand can build up in the 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.  
           [0007]    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.  
           [0008]    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.  
           [0009]    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® screen.” The ESS® system 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® system is constructed from three composite layers, including a slotted base pipe, a protective, perforated 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.  
           [0010]    [0010]FIG. 1 presents a section view showing a wellbore  40 . The wellbore  40  is lined with a string of casing  42 . The casing  42  separates the interior of the wellbore  40  from the surrounding earth formation  48 . An annular area is left between the casing  42  and the earth formation  48  and is filled with cement  46 , as is typical in a well completion. Extending downward below the cased portion of the wellbore  40  is an open hole portion  50 . The earth formation  48  forms the wall of the wellbore for the open hole portion  50 .  
           [0011]    Disposed in the open hole portion  50  of the wellbore  40  is an expandable tubular  20 . In the view of FIG. 1, the tubular  20  represents a sand screen  20 , such as Weatherford&#39;s ESS® sand screen. The expandable sand screen  20  is hung within the wellbore  40  from a hanging apparatus  32 . In some instances, the hanging apparatus  32  is a packer. In the depiction of FIG. 1, the hanging apparatus  32  is a liner  30  and liner hanger  32 .  
           [0012]    A production tubular  44  is also seen placed in the wellbore  40  of FIG. 1. The production tubular  44  extends from the surface and into a top portion of the liner  30 . A packer  34  is employed to seal the annulus between the production tubular  44  and the liner  30 .  
           [0013]    Also depicted in FIG. 1 is an instrumentation line  62 . The optional instrumentation line  62  runs within an encapsulation  12  from the earth surface (not shown) along the production tubular  44 . The encapsulation  12  is secured to the production tubular  44  by clamps, shown schematically at  18 . Clamps  18  are typically secured to the production tubular  44  approximately every ten meters. The encapsulation  12  passes through the liner hanger  32  (or utilized hanging apparatus), and extends downward to the top  21  of the sand screen  20 . In the arrangement shown in FIG. 1, the instrumentation line  62  enters a recess (shown at  10  in FIG. 2) in the outer diameter of the ESS®  20 . Arrangements for the recess  10  are described more fully in the pending application entitled “Profiled Recess for Instrumented Expandable Components,” having Ser. No. 09/964,034, which is incorporated herein in its entirety, by reference. However, the instrumentation line  62  may also be housed in a specially profiled encapsulation around the ESS®  20  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 Ser. No. 09/964,160, which is also incorporated herein in its entirety, by reference.  
           [0014]    [0014]FIG. 2 presents a cross-section of a sand screen  20 ′ within an open hole completion wellbore  50 ′. The sand screen  20 ′ is seen within a surrounding formation  48 . Three layers of the sand screen  20 ′ are shown, representing a base pipe  22 , a protective outer shroud  26 , and an intermediate filter media  24 . Slots  23  are seen within the base pipe  22  and the shroud  26 . A recess  10  is seen within the outer shroud  26  for receiving a pair of instrumentation lines  62 . In this arrangement, the instrumentation lines  62  are housed within tubular casings  60 .  
           [0015]    In FIGS. 1 and 2, the sand screens  20 ,  20 ′ are shown in their run-in positions. However, the sand screens  20 ,  20 ′ are configured to be expandable. In this manner, the sand screens  20 ,  20 ′ are expanded downhole against the adjacent formation  48  in order to preserve the integrity of the formation  48  during production. This step is presented in FIG. 3, which presents the open wellbore  50  with the sand screen  20  having been expanded.  
           [0016]    [0016]FIG. 4 presents the sand screen  20 ′ of FIG. 2, in its expanded state. Here, the sand screen  20 ′ has been expanded into radial frictional engagement with the surrounding formation  48 . Expansion of the sand screen  20 ′ obviates the need for a gravel pack, and allows for a larger i.d. within the production zone. 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.  
           [0017]    The expandable sand screens  20 ,  20 ′ are expanded by an expander tool  200 . An example of an expander tool  200  as may be used to expand a downhole tubular such as sand screen is seen in FIG. 5. FIG. 5 presents a perspective view of an expander tool  200 . The expander tool  200  first comprises a conical portion, or “cone”  210 . The cone  210  is urged through the inner bore of the sand screen  20  by pushing down or pulling up on a connected working string (not shown), or by otherwise translating the expander tool  200  such as through a downhole translation mechanism. The cone  210  has an outer diameter that is greater than the inner diameter of the sand screen  20 . As the cone is urged through the sand screen  20 , both the inner and outer diameters of the sand screen  20  are expanded.  
           [0018]    The expander tool  200  of FIG. 5 also comprises a hydraulically actuated tool portion  220 . The hydraulically actuated portion  220  defines a body  222  having a plurality of radially outward extending roller members  216 . The roller members  216  are urged outwardly away from the tool body  222  in response to fluid pressure applied within the perforated inner mandrel of the tool  200 .  
           [0019]    When it is desired to expand a tubular downhole, the expander tool  200  is translated axially (such as by raising and/or lowering the working string from the surface) along a desired length. Where a sand screen  20  is used as the expandable tubular, the expander tool  200  is translated along the length of the sand screen  20  in order to expand the inner and outer diameters of the screen  20 . The sand screen components  22 ,  26  are stretched past their elastic limit, thereby increasing the outer diameter of the sand screen  20 . In this way, the screen walls are placed closely adjacent to the borehole wall in full compliance, even in an irregular borehole.  
           [0020]    In order to obtain a radial expansion of a downhole tubular  20 , the expander tool  200  may also be rotated. This may be accomplished in various ways, such as by rotating the working string from the surface or by employing a downhole motor.  
           [0021]    Using expander means such as tool  200 , an expandable tubular  20  is subjected to outwardly radial forces that expand the diameter of the surrounding tubular  20 . It is understood, however, that other types of expander tools exist for expanding an elongated tubular body downhole. The description of the expander tool  200  shown in FIG. 5 is not intended to be a limitation as to how a sand screen or other expandable tubular might be expanded in the methods of the present invention.  
           [0022]    The sand screens  20 ,  20 ′ of FIGS. 1 and 2, while representing an improvement over prior gravel pack and sand screen devices, nevertheless have limitations. For example, the ESS® itself (if misapplied) is susceptible to the detrimental effects of fluid and sand particles flowing therethrough, including erosion, corrosion, and abrasion. In addition, the ESS® filter media  24  can become plugged with finer granular and clay particles if not correctly installed in contact with the borehole wall  48 , i.e., in “compliant expansion.” Finally, the layers  22 ,  24 ,  26  of the ESS® have limitations in terms of physical strength. In certain extreme cases where producing formations and wellbores are unstable or irregular and difficult to obtain a competent gravel pack, it may also be difficult to obtain fully compliant expandable screen installation. Therefore, it is desirable to support the ESS® system by injecting a thin cement column therearound. The cement sheath can cater for very large dimensional irregularities and, coupled with mechanical tubular support, can further stabilize the formation/wellbore.  
           [0023]    It is known to employ a column of porous and permeable cement as a substitute for a gravel pack. U.S. Pat. No. 6,390,195 issued to Nguyen in May of 2002 provides a method of forming a permeable cement sand screen in a wellbore adjacent to a fluid producing zone. Similarly, U.S. Pat. Nos. 6,202,751 and 6,364,945, issued in 2001 and 2002 respectively, to Chatterji, present compositions for such a permeable cement sand screen. The method of the &#39;195 patent includes the use of a perforated pipe within the wellbore at the producing zone. However, the pipe is not expanded, nor is it slotted. The use of slotted expandable pipe affords a significantly improved inflow area to the completion which aids fluid flow and thereby increases the economic benefit to the installation.  
           [0024]    Accordingly, a need exists for a method for completing a wellbore wherein an expandable sand screen is placed adjacent a production zone, and is assisted by a column of permeable granular material.  
         SUMMARY OF THE INVENTION  
         [0025]    An improved method for completing wells, such as hydrocarbon and water wells, is provided. According to methods of the present invention, an expandable, perforated tubular, such as a sand screen or a pre-slotted liner, is lowered into a wellbore. Thereafter, cement is injected into the wellbore so as to place a column of cement in the annular region between the tubular and the surrounding formation.  
           [0026]    In one aspect, the expandable tubular, e.g., sand screen, is expanded before cement is injected into the annular region. The tubular is not expanded into complete frictional engagement with the surrounding formation, but an annular region is preserved. In another aspect, the cement is injected into the annular region before the tubular is expanded. In this arrangement, the expansion operation is conducted before the cement is completely cured. In either aspect, a thin cylinder of cement is formed around the expandable tubular.  
           [0027]    After the sand screen has been expanded and the cement injected, the cement is cleaned out of the bore of the sand screen. In one aspect, this is accomplished by drilling the cement out of the bore. In another aspect, a treating fluid, e.g., an acid, is injected into the wellbore at the depth of the sand screen after the cement has been drilled out of the sand screen. The treating fluid imbues permeability and/or porosity characteristics to the cement, thereby permitting the flow of hydrocarbons therethrough.  
           [0028]    The cement serves to reinforce the expandable tubular, providing it with both improved physical strength and improved sand filtering ability. At the same time, the sand screen (or other expandable tubular) serves to reinforce the cement after it has cured. The use of cement in connection with the deployment of an expandable sand screen may be done in either an open hole completion, or in a cased wellbore. The use of cement in connection with an expandable sand screen may also be used to repair failed sand control completions within a wellbore.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    So that the manner in which the above recited features of the present invention, and other features contemplated and claimed herein, are attained and can be understood, a more particular description of the invention, briefly summarized above, may be had by reference to the appended drawings (FIGS. 7A through 8F). It is to be noted, however, that the 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.  
         [0030]    [0030]FIG. 1 presents a cross-sectional view of a wellbore. An expandable sand screen has been deployed in the wellbore. The sand screen has not yet been expanded.  
         [0031]    [0031]FIG. 2 provides a cross-sectional view of an expandable sand screen. The sand screen is shown within an open hole, in its unexpanded state.  
         [0032]    [0032]FIG. 3 presents the wellbore of FIG. 1, with the sand screen having been expanded into contact with the surrounding earth formation.  
         [0033]    [0033]FIG. 4 demonstrates a cross-sectional view of an expandable sand screen, with the sand screen having been radially expanded.  
         [0034]    [0034]FIG. 5 provides a perspective view of an expander tool as might be used in the methods of the present invention.  
         [0035]    [0035]FIG. 6A presents a cut-away view of an expandable sand screen as might be used in the methods of the present invention. The sand screen has not been expanded. Parts of the sand screen are exploded apart for clarity.  
         [0036]    [0036]FIG. 6B presents the expandable sand screen of FIG. 6A, incorporated into a run-in string and in series with completion tools. Here, the sand screen has been expanded by a tapered cone.  
         [0037]    [0037]FIGS. 7A-7E present steps for deploying a sand screen in accordance with one of the methods of the present invention. In each of these drawings, a cross-sectional view of a sand screen within a wellbore is provided.  
         [0038]    In FIG. 7A, the sand screen has been run into the wellbore. The sand screen has not yet been expanded.  
         [0039]    In FIG. 7B, the sand screen is being radially expanded along its length. In this arrangement, a tapered cone is being used as the expander tool.  
         [0040]    [0040]FIG. 7C shows cement being squeezed up the annular region defined by the sand screen and the surrounding formation.  
         [0041]    The expanded sand screen is again shown in the view of FIG. 7D. Here, the expander tool has been removed from the wellbore, and the working string has been reintroduced into the wellbore with a drill bit at the lower end. The drill bit is shown drilling out cement deposited or left inside the sand screen.  
         [0042]    [0042]FIG. 7E presents the wellbore of FIG. 7A having been completed. The drill bit is removed from the wellbore, and fluids are being produced through the cement column and through the sand screen. Arrows depict the flow of fluids, e.g., hydrocarbons, into the wellbore.  
         [0043]    [0043]FIGS. 8A-8E present steps for deploying a sand screen in accordance with another of the methods of the present invention. In each of these drawings, a cross-sectional view of a wellbore is again seen. Here, the wellbore is cased.  
         [0044]    In FIG. 8A, a string of casing is shown within the wellbore. The casing string has been perforated.  
         [0045]    [0045]FIG. 8B demonstrates a sand screen being run into the wellbore of FIG. 8A. The sand screen is located at a depth that traverses the perforated zone. In this arrangement, a mule shoe at the lower end of the sand screen rests at the bottom of the borehole. An expander tool is temporarily attached at the top end of the sand screen. The sand screen has not yet been expanded  
         [0046]    In FIG. 8C, the sand screen is being radially expanded along its length. In this arrangement, a tapered cone is again being used as the expander tool. A packer is seen set above the sand screen.  
         [0047]    [0047]FIG. 8D shows cement being squeezed up the annular region defined by the sand screen and the surrounding formation.  
         [0048]    The expanded sand screen is shown in the view of FIG. 8E. The cone has been removed from the wellbore, and the working string has been reintroduced into the wellbore, with a drill bit at the lower end. The drill bit is shown drilling out cement inside the sand screen.  
         [0049]    [0049]FIG. 8F presents the wellbore of FIG. 8B having been completed. The drill bit is removed from the wellbore, and fluids are being produced through the cement column and through the sand screen. Arrows depict the flow of fluids, e.g., hydrocarbons, into the wellbore. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0050]    [0050]FIG. 6A presents a more detailed view of an expandable sand screen  100  as might be used in the methods of the present invention. FIG. 6A is a cut-away view taken along the longitudinal axis of the tool  100 . The outer protective shroud  126  is seen around the sand screen  100 , while the inner base pipe  122  is seen along the cut-away portion of the drawing. A filtration media  124  is disposed between the outer shroud  126  and the base pipe  122 . In the view of FIG. 6A, the filtration media  124  is seen only through the slotted outer shroud  126 .  
         [0051]    In the arrangement shown in FIG. 6A, the expandable sand screen  100  defines three distinct portions: (1) a top connector  110 ; (2) one or more expandable sand screen joints  120 ; and (3) a bottom connector  130 . The top connector  110 , the sand screen joint  120 , and the bottom connector  130  are exploded apart for clarity.  
         [0052]    First, the top connector  110  serves to connect the sand screen joints  120  to a working string (such as the drill string shown at  70  in FIGS. 7A-7E). In some instances, a blank pipe (not shown) is placed between the top connector  110  and the working string. The top connector  110  includes an upward stub Acme box connection member  112  at its top end. The top connector  110  also has a male threaded connection member  114  at its lower end. Intermediate the upper  112  and lower  114  connectors, the top connector  110  has a body  116  having a pre-formed shape. The body  126  is configured to receive and house an expander tool, such as tool  200  shown in FIG. 5, during run-in.  
         [0053]    Before expansion operations are conducted, a suitable sized expander tool  200  can be installed into the top connector  100  at the job site. To retain the expander tool  200  in position, shear screws (not shown) are installed through the expander tool&#39;s body  202 . Thus, the expander tool  200  is releasably connected to the top connector  100 .  
         [0054]    Second, one or more sand screen joints  120  are provided. ESS® joints are typically provided in 38 foot lengths. As noted, the ESS® joints  120  are comprised of three layers, to wit, a slotted steel tube known as a “base pipe”  122 , overlapping layers of filtering membrane, i.e., “an intermediate filter media”  124 , and a pre-slotted steel plate  126  wrapped around the base pipe  122  and the filter media  124 . The filter media  124  allows hydrocarbons to invade the wellbore, but filters sand and other unwanted particles from entering.  
         [0055]    The sand screen joints  120  are configured to be expandable. Expansion is achieved either by using a compliant expander tool, by passing a tapered cone through the inside of the joint  120 , or by using an expander tool that incorporates both features, such as tool  200  shown in FIG. 5. During the expansion process, both inner  122  and outer  126  layers of the joints  120  are plastically deformed to achieve the desired dimension. The overlapping filter membranes  124  slide over one another to accommodate the increase in diameter.  
         [0056]    Third, a bottom connector  130  is provided in the ESS®  100 . The bottom connector  130  has a top end  132  that connects to the bottom of the sand screen joint  120 . The bottom connector  130  provides a positive location for receiving the expander tool  200  after the expansion process is completed. In one arrangement, the expander tool  200  remains in the wellbore after the expansion process is completed, with the working string being detachable from the expander tool  200 . In one aspect, the bottom connector  130  connects at a lower end  134  to a shoe assembly (seen at  180  in FIG. 6B).  
         [0057]    In operation, the sand screen  100  is run into a wellbore at the end of a working string. FIG. 6B presents the expandable sand screen  100  of FIG. 6A, incorporated into a run-in string  70 , and in series with completion tools. The completion tools include a hanger  140 , a packer  150 , and a shoe assembly  180 . The hanger  140  includes slip members  144  having wickers for frictionally engaging a surrounding casing string (not shown in FIG. 6B). The packer  150  includes a sealing element  154  for sealing engaging the surrounding wellbore once the packer  150  is set. FIG. 6B also shows in somewhat schematic fashion, a tapered cone  210  releasably held within the sand screen  100 . Here, the sand screen  100  has been expanded along its length. Note again, though, that the methods of the present invention are not limited by the type of expander tool used for the expansion operation.  
         [0058]    In some instances, the sand screen  100  is deployed in a wellbore having an open hole completion. FIGS. 7A-7E present steps for deploying a sand screen  100  in accordance with one of the methods of the present invention. In each of these drawings, a cross-sectional view of the sand screen  100  within an open hole wellbore  40  is provided. Thus, the wellbore  40  has an open hole portion  50 . It is also understood that the sand screen  100  shown in FIGS. 7A-7E is exemplary. The present methods are equally applicable for other expandable tubulars, such as expandable casing liners and alternative borehole liners.  
         [0059]    In FIG. 7A, the sand screen  100  has been run into the wellbore  40  at the end of a working string  70 . In this respect, the sand screen  100  is releasably attached to an expander tool  200 ′. The expander tool  200 ′, in turn, is attached to the lower end of the working string  70 . A liner hanger  140  is provided to hang the sand screen  100  once it is lowered to the desired producing zone. A packer  150  is also shown. It is understood, of course, that other completion tools may be used, such as a run-in tool.  
         [0060]    [0060]FIG. 7B presents the next step in the completion process. In FIG. 7B, the liner hanger  140  and packer  150  have been set in the wellbore  40 . Axial stress has sheared the shear pins (not shown), releasing the cone  200 ′ from the top connector (shown as  110  in FIG. 6A). This allows the cone  200 ′ to move downward relative to the expandable tubular  100 . The cone  200 ′ is moved downward at the lower end of the working string  70 . As the cone  200 ′ is urged downward, the expandable tubular  100  is radially expanded along its length. The tubular  100  is not expanded into complete frictional engagement with the surrounding formation  48 , but an annular region is preserved. In the arrangement of FIG. 7B, a tapered cone is being used as the expander tool  200 ′. However, it is again understood that the methods of the present invention are not limited to the manner in which expansion is accomplished, or the type of expander tool used.  
         [0061]    [0061]FIG. 7C presents the next step in the completion process. Here, cement  55  is being injected through the working string  70 , through the expander tool  200 ′, and out of the mule shoe  180 . The cement  55  is then squeezed up the annular region defined by the sand screen  100  and the surrounding formation wall  48 . In this way, a thin tubular column of cement  55  is placed in the open hole portion  50  of the wellbore  40 .  
         [0062]    It is noted that the sand screen  100  in FIG. 7C is held in tension during the cementing and expansion process. However, the methods of the present invention are not limited to an arrangement where the sand screen  100  (or other expandable tubular) is held in tension. It is understood that the expander tool, e.g., expansion cone, can be deployed in a position inverted from that shown in the drawings. In such an arrangement, the expander tool  200  is releasably attached to the sand screen  100  (or some tool below the sand screen  100 ), and is then pulled upward through the sand screen  100  during the expansion process. The sand screen  100  would then be expanded in compression against the hanger  140  as the expander tool  200  is pulled upwards. Alternatively, the expandable tubular  100  may be expanded in compression by resting the sand screen  100  on and against a cement shoe  180  or “mule shoe.” The mule shoe may be drillable and would be part of the deployment equipment. No hanger would be required because the cement shoe  180  would be resting on the bottom of the borehole. In this alternate arrangement, the cone  200  would again be releasably attached to the top connector  110  (or otherwise above the sand screen  100 ), or form part of an expansion string.  
         [0063]    It should also be noted that the steps in FIGS. 7B and 7C may be reversed. In this respect, the cement  55  may be injected into the annular region before the tubular  100  is expanded. The expansion operation is then conducted before the cement  55  has completely cured. Any cement deposited in the main bore of the sand screen  100  (or other expandable tubular) is then drilled out.  
         [0064]    [0064]FIG. 7D demonstrates the optional step of drilling cement  55  out of the main bore of the sand screen  100 . The sand screen  100  in its expanded state is shown in the view of FIG. 7D. The expander tool  200 ′ (and run-in tool) has been removed from the wellbore  40 , and the working string  70  has been reintroduced into the wellbore  40 . A drill bit  75  is now seen at the lower end of the working string  70 . In the step of FIG. 7D, the drill bit is drilling out cement  55  that is inside the sand screen  100 . A thin cement sheath  55 ′ is now left around the sand screen  100 .  
         [0065]    Next, FIG. 7E presents the wellbore of FIG. 7A having been completed. The drill bit  75  has been removed from the wellbore  40 , and fluids are being produced through the cement column  55  and through the sand screen  100 . Arrows  15  depict the flow of fluids, such as hydrocarbons, into the wellbore  40 .  
         [0066]    [0066]FIGS. 8A-8E present steps for deploying a sand screen in accordance with another of the methods of the present invention. In each of these drawings, a cross-sectional view of a wellbore  40  is again seen. In this instance, the wellbore  40  is cased with a string of casing, such as a liner string  30 .  
         [0067]    In FIG. 8A, a liner string  30  is shown within the wellbore  40 . The liner string  30  has been perforated. FIG. 8A could represent a new wellbore that is just being completed with new perforations  35 ; alternatively, it could represent an old well having perforated casing that has corroded and is in need of support provided by a sand screen.  
         [0068]    [0068]FIG. 8B demonstrates the sand screen  100  being run into the wellbore  40  of FIG. 8A at the end of a working string  70 . The sand screen  100  is temporarily connected to the working string  70  via a run-in tool (not shown). A packer  150  is positioned above the sand screen  100 . The sand screen  100  is releasably attached to an expander tool  200 ′, while the expander tool  200 ′, in turn, is attached to the lower end of the working string  70 . The sand screen  100  is located at a depth that traverses the perforated zone of the liner string  30 . In the arrangement of FIG. 8B, the sand screen  100  is simply landed on the bottom of the open borehole  50 . A mule shoe  180  is shown resting at the bottom of the hole.  
         [0069]    [0069]FIG. 8C presents the next step in the completion process. In FIG. 8C, the packer  150  has been set in the wellbore  40 . A liner hanger is not needed in this arrangement, as the sand screen  100  is resting at the bottom of the hole. Axial stress has sheared the shear pins (not shown), releasing the cone  200 ′ from the top connector (shown as  110  in FIG. 6A). This allows the cone  200 ′ to move downward relative to the expandable tubular  100 . The cone  200 ′ is moved downward at the lower end of the working string  70 . As the cone  200 ′ is urged downward, the expandable tubular  100  is radially expanded along its length. The tubular  100  is not expanded into complete frictional engagement with the surrounding formation  48 , but an annular region is preserved. In the arrangement of FIG. 8C, a tapered cone is again being used as the expander tool  200 ′. However, it is again understood that the methods of the present invention are not limited to the manner in which expansion is accomplished, or the type of expander tool used.  
         [0070]    [0070]FIG. 8D presents the next step in the completion process. Here, cement  55  is being injected through the working string  70 , through the expander tool  200 ′, and out of the mule shoe  180 . The cement  55  is then squeezed up the annular region defined by the sand screen  100  and the surrounding formation wall  48 . In this way, a thin tubular column of cement  55  is placed in the open hole portion  50  of the wellbore  40 .  
         [0071]    It is noted in the arrangement of FIG. 8D that the working string  70  and the expander tool  200 ′ have been raised in the wellbore  40 . This allows cement  55  to also fill all or a portion of the main bore of the expandable tubular  100 . In this respect, it is optional in the methods of the present invention to place cement  55  not only in the annular region outside of the sand screen  100 , but also within the sand screen  100  or other expandable tubular itself.  
         [0072]    The sand screen  100  of FIG. 8B is shown in its expanded state in the view of FIG. 8E. Here, the sand screen  100  has been expanded along a desired length. The expander tool  200  has been removed from the wellbore  40 , and the working string  70  has been reintroduced into the wellbore  40 . A drill bit  75  is now seen at the lower end of the working string  70 . In the step of FIG. 8E, the drill bit is drilling out at least a portion of the cement  55  that is inside the sand screen  100 . A thin cement sheath  55 ′ is now left around the sand screen  100 .  
         [0073]    [0073]FIG. 8F presents the wellbore  40  of FIG. 8B having been completed. The drill bit  75  is removed from the wellbore  40 , and fluids are being produced through the cement column  55 ′ and through the sand screen  100 . Arrows  15  depict the flow of fluids, such as hydrocarbons, into the wellbore  40 .  
         [0074]    In order for the methods shown in FIGS. 7A-7E, and FIGS. 8A-8F to work most effectively, it is desirable to provide cement  55  having characteristics of increased permeability. The cement pore sizes should, after cure, be sized to prevent the formation sand grains from passing through under pressure, while still allowing the passage of fluids and clay (fines) particles. In this manner, the cement  55  aids in the sand filtering process without preventing the flow of valuable hydrocarbons into the wellbore  40 . An example is a hollow fiber cement, which provides small pore passages incorporated within the structure of the cement. The hollow fiber tubules also improve the structural integrity of the cement sheath. Alternatively, a permeable cement such as that described in U.S. Pat. Nos. 6,364,945 and 6,202,751, mentioned earlier, may be employed. The &#39;945 and the &#39;751 patents are incorporated herein by reference, in their respective entireties.  
         [0075]    When using a porous and permeable cement, the operator may introduce an acid to create interconnecting vugs and channels in the cement. This procedure is set out more fully in U.S. Pat. No. 6,390,195, mentioned earlier. The &#39;195 patent is also incorporated herein by reference, in its entirety. In one aspect, the cement is comprised of a hydraulic cement, a particulate cross-linked gel containing an internal breaker which after time causes said gel to break into a liquid, and water present in an amount sufficient to form a slurry. After the cement has been injected into the wellbore, and after it has been drilled out of the sand screen, the delayed internal breaker in the cement breaks. Acid is then introduced into the wellbore and through the sand screen where it comes into contact with the set cement. The acid dissolves portions of the set cement composition connecting the channels therein such that the set cement column  55 ′ is permeated substantially along its length and width. The well is then ready for production, as shown in FIGS. 7E and 8F.  
         [0076]    In one arrangement, the cement includes a particulate solid that is soluble in the presence of a treating fluid, such as acid. The acid dissolves the particulate solids, thereby creating vugs and channels through which hydrocarbons flow. In another aspect, the cement composition further comprises a gas present in an amount sufficient to form a foam, and a mixture of foaming and foam stabilizing surfactants.  
         [0077]    Because the porous and permeable cement would introduce a pressure drop into the completion, it is desirable that the thickness of the cement sheath be minimized. The use of an expandable tubular, such as an expandable sand screen or slotted liner, allows the greatest possible inflow area into the wellbore through the permeable cement, thereby minimizing cement thickness and pressure drop. In addition, the use of an expandable tubular allows wells to be under-reamed, thereby allowing significant inflow advantages over conventional completion techniques. Furthermore, since the tubular actually expands to an inside diameter greater than the maximum outside diameter of the expander tool, the final inside diameter of the tubular can be substantially equal to that of the parent casing. This provides a larger filtering surface area, resulting in a lower pressure drop than using a conventional, non-expandable perforated pipe, and greater longevity due to the number of pores available for flow. Further, the use of an expandable tubular to support the cement sheath  55 ′ provides additional security in case of thermal or pressure related stress cracking to the cement  55 ′. Wellbore support is provided even in extreme wash-outs and reactive shales. Thus, the above methods when used in cased and perforated wells are highly erosion resistant as the sand grains are kept in place.  
         [0078]    It should also be noted that the methods of the present invention may be used with a combination of permeable and non-permeable cement in a multi-stage cement job. In this respect, a producing zone can be isolated by cementing the annulus above and below the producing zone with a non-permeable cement. A permeable cement can be squeezed into the area adjacent the producing zone. The multi-stage cement job can be done in various steps—the order is not important for purposes of the present inventions. By using normal cement and permeable cement in a multi-stage cement job coupled with the tubular mechanical support provided by the expandable sand screen or tubular, a stable and effective sand control method can be provided without gravel packing and perforating operations.  
         [0079]    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, a crossover port and a cement shoe can be added to the deployment equipment. The sand screen or tubular would be expanded after the cement is poured. The cement would then be pumped through the expansion cone while it is on bottom and up through a preserved annulus between the sand screen and the wall of the borehole. The cement would not pass through the sand screen, so no drilling step would be required. The deployment equipment is then retrieved, leaving a clean production bore.

Technology Classification (CPC): 4