US20040251033A1

US20040251033A1 - Method for using expandable tubulars

Info

Publication number: US20040251033A1
Application number: US10/459,387
Authority: US
Inventors: John Cameron; Calum Whitelaw
Original assignee: Weatherford Lamb Inc
Current assignee: Weatherford Lamb Inc
Priority date: 2003-06-11
Filing date: 2003-06-11
Publication date: 2004-12-16

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.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

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.

2. Description of 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.

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.

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® 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.

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.

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'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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 '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.

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

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.

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.

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.

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

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. [0029]
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. [0030]
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. [0031]
FIG. 3 presents the wellbore of FIG. 1, with the sand screen having been expanded into contact with the surrounding earth formation. [0032]
FIG. 4 demonstrates a cross-sectional view of an expandable sand screen, with the sand screen having been radially expanded. [0033]
FIG. 5 provides a perspective view of an expander tool as might be used in the methods of the present invention. [0034]
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. [0035]
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. [0036]
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. [0037]
In FIG. 7A, the sand screen has been run into the wellbore. The sand screen has not yet been expanded. [0038]
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. [0039]
FIG. 7C shows cement being squeezed up the annular region defined by the sand screen and the surrounding formation. [0040]
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. [0041]
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. [0042]
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. [0043]
In FIG. 8A, a string of casing is shown within the wellbore. The casing string has been perforated. [0044]
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 [0045]
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. [0046]
FIG. 8D shows cement being squeezed up the annular region defined by the sand screen and the surrounding formation. [0047]
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. [0048]
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.[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 6A presents a more detailed view of an [0050] 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.
In the arrangement shown in FIG. 6A, the [0051] 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.
First, the [0052] 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.
Before expansion operations are conducted, a suitable [0053] 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's body 202. Thus, the expander tool 200 is releasably connected to the top connector 100.
Second, one or more [0054] 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.
The [0055] 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.
Third, a [0056] 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).
In operation, the [0057] 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.
In some instances, the [0058] 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.
In FIG. 7A, the [0059] 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.
FIG. 7B presents the next step in the completion process. In FIG. 7B, the [0060] 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.
FIG. 7C presents the next step in the completion process. Here, [0061] 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.
It is noted that the [0062] 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.
It should also be noted that the steps in FIGS. 7B and 7C may be reversed. In this respect, the [0063] 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.
FIG. 7D demonstrates the optional step of drilling [0064] 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.
Next, FIG. 7E presents the wellbore of FIG. 7A having been completed. The [0065] 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.
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 [0066] wellbore 40 is again seen. In this instance, the wellbore 40 is cased with a string of casing, such as a liner string 30.
In FIG. 8A, a [0067] 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.
FIG. 8B demonstrates the [0068] 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.
FIG. 8C presents the next step in the completion process. In FIG. 8C, the [0069] 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.
FIG. 8D presents the next step in the completion process. Here, [0070] 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.
It is noted in the arrangement of FIG. 8D that the working [0071] 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.
The [0072] 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.
FIG. 8F presents the [0073] 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.
In order for the methods shown in FIGS. 7A-7E, and FIGS. 8A-8F to work most effectively, it is desirable to provide [0074] 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 '945 and the '751 patents are incorporated herein by reference, in their respective entireties.
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 '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 [0075] 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.
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. [0076]
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 [0077] 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.
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. [0078]
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. [0079]

Claims

1. A method for using an expandable tubular within a wellbore, comprising the steps of:

running the tubular into the wellbore;

locating the tubular in the wellbore adjacent a producing zone;

expanding the tubular radially outward along a desired length; and

placing cement in an annular region defined by the area between the expanded tubular and the surrounding wellbore.

2. The method of claim 1, wherein the wellbore along the producing zone is an open hole wellbore, allowing fluid communication between an earth formation at the producing zone and the expanded tubular.

3. The method of claim 1, wherein the wellbore along the producing zone is cased with a string of perforated casing, allowing fluid communication between an earth formation at the producing zone and the expanded tubular.

4. The method of claim 1, wherein the cement is a permeable and porous cement that permits fluids to flow from the earth formation to the expanded tubular.

5. The method of claim 4, wherein the method is conducted to remedy a failed completion.

6. The method of claim 4, wherein the step of placing cement in the annular region is performed by injecting cement through a tubular string, and then forcing a portion of the injected cement around the bottom of the expanded tubular and up into the annular region.

7. The method of claim 4, further comprising the step of:

removing substantially all of any cement disposed within the expanded tubular, leaving a cylindrical cement column in the annular region around the tubular.

8. The method of claim 7, wherein the step of removing substantially all of the cement disposed within the tubular is performed by drilling out the cement after it has substantially cured.

9. The method of claim 4, wherein the tubular is an expandable sand screen.

10. The method of claim 9, further comprising the step of:

injecting a treating fluid into and through the sand screen in order to contact and treat the cement column, the treating fluid increasing the permeability of the set cement.

11. The method of claim 10, wherein the step of injecting the treating fluid is performed after the step of expanding the sand screen.

12. The method of claim 4, wherein 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.

13. The method of claim 12, further comprising the step of:

injecting a treating fluid into and through the sand screen in order to contact and treat the cement column, the treating fluid increasing the permeability of the set cement; and

wherein the cement is further comprised of a particulate solid that is soluble in the presence of the treating fluid.

14. The method of claim 1, wherein the step of expanding the tubular is performed by using an expander tool, the expander tool comprising a tapered cone portion urged axially within the tubular.

15. The method of claim 14, wherein the expander tool further comprises a hydraulically actuated tool portion.

16. A method for forming a permeable cement sand barrier in a wellbore, the wellbore having a wall, the method comprising the steps of:

deploying a perforated expandable tubular at a selected depth;

expanding the tubular;

injecting a permeable cement composition into the annulus formed between the wall of the wellbore and the perforated expandable tubular; and

allowing the cement composition to set.

17. The method of claim 16, wherein the permeable cement defines a composition comprised of:

a hydraulic cement,

a particulate cross-linked gel containing an internal breaker which after time causes the gel to break into a liquid, allowing the particulate cross-linked gel containing the internal breaker to break so that vugs and channels are formed in the cement composition as the cement composition sets; and

water present in an amount sufficient to form a slurry.

18. The method of claim 17, further comprising the step of:

allowing the particulate cross-linked gel containing the internal breaker to break.

19. The method of claim 18,

wherein the cement composition further comprises an acid soluble particulate solid; and

the method further comprises the step of introducing an acid solvent into the perforated pipe whereby the acid solvent flows through the perforations in the pipe and into contact with the set cement composition so as to dissolve the acid soluble particulate solid, thereby creating channels for the flow of hydrocarbons therethrough.

20. The method of claim 19, wherein 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.

21. The method of claim 16, wherein the perforated expandable tubular is an expandable sand screen.

22. A method for using an expandable tubular within a wellbore, comprising the steps of:

running the tubular into the wellbore;

locating the tubular in the wellbore adjacent a producing zone;

placing cement in an annular region defined by the area between the tubular and the surrounding wellbore; and

expanding the tubular radially outward along a desired length before the cement has cured.

23. The method of claim 22, wherein the expandable tubular is an expandable sand screen.

24. The method of claim 22, further comprising the step of:

hanging the expandable sand screen within the wellbore before the step of expanding the sand screen radially is conducted.