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BACKGROUND  
       [0001]     The present invention relates generally to equipment utilized and operations performed in conjunction with subterranean wells and, in embodiments described herein, more particularly provides well tools with actuators utilizing swellable materials.  
         [0002]     Many well tools are commercially available which are actuated by manipulation of a tubular string from the surface. Packers, liner hangers, jars, etc. are some examples of these. Other well tools may be actuated by intervention into a well, such as by using a wireline, slickline, coiled tubing, etc. Still other well tools may be actuated utilizing lines extending to the surface, such as electrical, hydraulic, fiber optic and other types of lines. Telemetry-controlled well tools are also available which are actuated in response to electromagnetic, acoustic, pressure pulse and other forms of telemetry.  
         [0003]     However, each of these actuation methods has its drawbacks. Manipulation of tubular strings from the surface is time-consuming and labor-intensive, and many well operations cannot be performed during manipulation of a tubing string. Intervention into a well with wireline, slickline, coiled tubing, etc., typically obstructs the wellbore, impedes flow, requires a through-bore for the intervention, requires specialized equipment and presents other difficulties. Electrical, hydraulic and fiber optic lines are relatively easily damaged and require special procedures and equipment during installation. Telemetry requires expensive sophisticated signal transmitting, receiving and processing equipment and is limited by factors such as distance, noise, etc.  
         [0004]     It will, thus, be readily appreciated that improvements are needed in the art of actuating well tools.  
       SUMMARY  
       [0005]     In carrying out the principles of the present invention, well tool actuation devices and methods are provided which solve at least one problem in the art. One example is described below in which a swellable material is utilized in an actuator for a well tool. Another example is described below in which a swellable material applies a biasing force to cause displacement of a member of a well tool actuator.  
         [0006]     In one aspect of the invention, a unique well tool is provided. The well tool includes an actuator which actuates the well tool in response to contact between a swellable material and a well fluid.  
         [0007]     In another aspect of the invention, a method of actuating a well tool is provided. The method includes the steps of: installing the well tool including an actuator; contacting a swellable material of the actuator with a well fluid; and actuating the well tool in response to the contacting step.  
         [0008]     In yet another aspect of the invention, a well system includes a well tool having a flow control device and a swellable material. The well tool is operative to control flow through a passage of a tubular string in response to contact between the swellable material and well fluid.  
         [0009]     These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings, in which similar elements are indicated in the various figures using the same reference numbers. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a schematic partially cross-sectional view of a well system embodying principles of the present invention;  
         [0011]      FIGS. 2A  &amp; B are schematic cross-sectional views of a first well tool which may be used in the system of  FIG. 1 ;  
         [0012]      FIGS. 3A  &amp; B are schematic cross-sectional views of a second well tool which may be used in the system of  FIG. 1 ;  
         [0013]      FIGS. 4A  &amp; B are schematic cross-sectional views of an actuator for a third well tool which may be used in the system of  FIG. 1 ;  
         [0014]      FIGS. 5A  &amp; B are schematic cross-sectional views of a fourth well tool which may be used in the system of  FIG. 1 ; and  
         [0015]      FIGS. 6A  &amp; B are schematic cross-sectional views of an alternate construction of the fourth well tool. 
     
    
     DETAILED DESCRIPTION  
       [0016]     It is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention. The embodiments are described merely as examples of useful applications of the principles of the invention, which is not limited to any specific details of these embodiments.  
         [0017]     In the following description of the representative embodiments of the invention, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. In general, “above”, “upper”, “upward” and similar terms refer to a direction toward the earth&#39;s surface along a wellbore, and “below”, “lower”, “downward” and similar terms refer to a direction away from the earth&#39;s surface along the wellbore.  
         [0018]     Representatively illustrated in  FIG. 1  are a well system  10  and associated methods which embody principles of the present invention. The well system  10  includes a casing string or other type of tubular string  12  installed in a wellbore  14 . A liner string or other type of tubular string  16  has been secured to the tubular string  12  by use of a liner hanger or other type of well tool  18 .  
         [0019]     The well tool  18  includes an anchoring device  48  and an actuator  50 . The actuator  50  sets the anchoring device  48 , so that the tubular string  16  is secured to the tubular string  12 . The well tool  18  may also include a sealing device (such as the sealing device  36  described below) for sealing between the tubular strings  12 ,  16  if desired.  
         [0020]     The well tool  18  is one example of a wide variety of well tools which may incorporate principles of the invention. Other types of well tools which may incorporate the principles of the invention are described below. However, it should be clearly understood that the invention is not limited to use only with the well tools described herein, and these well tools may be used in other well systems and in other methods without departing from the principles of the invention.  
         [0021]     In addition to the well tool  18 , the well system  10  includes well tools  20 ,  22 ,  24 ,  26 ,  28  and  30 . The well tool  20  includes a flow control device (for example, a valve or choke, etc.) for controlling flow between an interior and exterior of a tubular string  32 . As depicted in  FIG. 1 , the well tool  20  also controls flow between the interior of the tubular string  32  and a formation or zone  34  intersected by an extension of the wellbore  14 .  
         [0022]     The well tool  22  is of the type known to those skilled in the art as a packer. The well tool  22  includes a sealing device  36  and an actuator  38  for setting the sealing device, so that it prevents flow through an annulus  40  formed between the tubular strings  16 ,  32 . The well tool  22  may also include an anchoring device (such as the anchoring device  48  described above) for securing the tubular string  32  to the tubular string  16  if desired.  
         [0023]     The well tool  24  includes a flow control device (for example, a valve or choke, etc.) for controlling flow between the annulus  40  and the interior of the tubular string  32 . As depicted in  FIG. 1 , the well tool  24  is positioned with a well screen assembly  42  in the wellbore  14 . Preferably, the flow control device of the well tool  24  allows the tubular string  32  to fill as it is lowered into the well (so that the flow does not have to pass through the screen assembly  42 , which might damage or clog the screen) and then, after installation, the flow control device closes (so that the flow of fluid from a zone  44  intersected by the wellbore  14  to the interior of the tubular string is filtered by the screen assembly).  
         [0024]     The well tool  26  is of the type known to those skilled in the art as a firing head. The well tool  26  is used to detonate perforating guns  46 . Preferably, the well tool  26  includes features which prevent the perforating guns  46  from being detonated until they have been safely installed in the well.  
         [0025]     The well tool  28  is of the type known to those skilled in the art as a cementing shoe or cementing valve. Preferably, the well tool  28  allows the tubular string  16  to fill with fluid as it is being installed in the well, and then, after installation but prior to cementing the tubular string in the well, the well tool permits only one-way flow (for example, in the manner of a check valve).  
         [0026]     The well tool  30  is of the type known to those skilled in the art as a formation isolation valve or fluid loss control valve. Preferably, the well tool  30  prevents downwardly directed flow (as viewed in  FIG. 1 ) through an interior flow passage of the tubular string  32 , for example, to prevent loss of well fluid to the zone  44  during completion operations. Eventually, the well tool  30  is actuated to permit downwardly directed flow (for example, to allow unrestricted access or flow therethrough).  
         [0027]     Although only the actuators  38 ,  50  have been described above for actuating the well tools  18 ,  22 , it should be understood that any of the other well tools  20 ,  24 ,  26 ,  28 ,  30  may also include actuators. However, it is not necessary for any of the well tools  18 ,  20 ,  22 ,  24 ,  26 ,  28 ,  30  to include a separate actuator in keeping with the principles of the invention.  
         [0028]     Referring additionally now to  FIGS. 2A  &amp; B, an enlarged scale schematic cross-sectional view of the well tool  30  is representatively illustrated, apart from the remainder of the well system  10 . The well tool  30  is depicted in  FIG. 2A  in a configuration in which the well tool is initially installed in the well, and in  FIG. 2B  the well tool is depicted in a configuration in which the well tool has been actuated in the well.  
         [0029]     The well tool  30  includes a flow control device  54  in the form of a flapper or other type of closure member  52  which engages a seat  56  to prevent downward flow through a flow passage  58 . When used in the well system  10 , the flow passage  58  would extend through the interior of the tubular string  32 .  
         [0030]     Instead of the flapper closure member  52 , the flow control device  54  could include a ball closure (for example, of the type used in subsea test trees or safety valves), a variable flow choking mechanism or any other type of flow control. In addition, it should be understood that it is not necessary for the well tool  30  to permit one-way flow through the passage  58 , either when the well tool is initially installed in the well, or when the well tool is subsequently actuated.  
         [0031]     The well tool  30  also includes an actuator  60  for actuating the flow control device  54 . The actuator  60  includes a swellable material  62  and an elongated member  64 . Displacement of the actuator member  64  in a downward direction causes the closure member  52  to pivot upwardly and disengage from the seat  56 , thereby permitting downward flow of fluid through the passage  58  (as depicted in  FIG. 2B ).  
         [0032]     The swellable material  62  swells (increases in volume) when contacted with a certain fluid in the well. For example, the material  62  could swell in response to contact with water, in response to contact with hydrocarbon fluid, or in response to contact with gas in the well, etc. Ports  66  may be provided in the actuator  60  to increase a surface area of the material  62  exposed to the fluid in the well.  
         [0033]     Examples of swellable materials are described in U.S. patent application publication nos. 2004-0020662, 2005-0110217, 2004-0112609, and 2004-0060706, the entire disclosures of which are incorporated herein by this reference. Other examples of swellable materials are described in PCT patent application publication nos. WO 2004/057715 and WO 2005/116394.  
         [0034]     When contacted by the appropriate fluid for a sufficient amount of time (which may be some time after installation of the well tool  30  in the well), the material  62  increases in volume and applies a downwardly directed biasing force to the actuator member  64 . This causes the member  64  to displace downward and thereby pivot the closure member  52  upward.  
         [0035]     Other mechanisms and devices may be present in the well tool  30  although they are riot depicted in  FIGS. 2A  &amp; B for clarity of illustration and description. For example, the flow control device  54  could include a spring or other biasing mechanism for maintaining the closure member  52  in sealing engagement with the seat  56  prior to the actuator  60  causing the closure member to pivot upward.  
         [0036]     The ports  66  are depicted as providing for contact between the material  62  and fluid in the passage  58 . However, it will be appreciated that the ports  66  could be positioned to alternatively, or in addition, provide for contact between the material  62  and fluid in the annulus  40  on the exterior of the well tool  30  (similar to the ports  82  described below and depicted in  FIGS. 3A  &amp; B).  
         [0037]     The fluid (e.g., hydrocarbon liquid, water, gas, etc.) which contacts the material  62  to cause it to swell may be introduced at any time. The fluid could be in the well at the time the well tool  30  is installed in the well. The fluid could be flowed into the well after installation of the well tool  30 . For example, if the fluid is hydrocarbon fluid, then the fluid may contact the material  62  after the well is placed in production.  
         [0038]     Referring additionally now to  FIGS. 3A  &amp; B, an enlarged scale schematic cross-sectional view of the well tool  20  is representatively illustrated, apart from the remainder of the well system  10 . The well tool  20  is depicted in  FIG. 3A  in a configuration in which the well tool is initially installed in the well, and in  FIG. 3B  in a configuration in which the well tool has been actuated in the well.  
         [0039]     The well tool  20  includes the swellable material  62  in an actuator  68  for a flow control device  70 . The actuator  68  and flow control device  70  are similar in some respects to the actuator  60  and flow control device  54  of the well tool  30  as described above.  
         [0040]     However, the flow control device  70  is used to selectively control flow through flow passages  72  and thereby control flow between the exterior and interior of the tubular string  32 . For this purpose, the flow control device  70  includes a sleeve  74  having openings  76  and seals  78 .  
         [0041]     As depicted in  FIG. 3B , the openings  76  are aligned with the passages  72 , and so flow between the interior and exterior of the tubular string  32  (or between the passage  58  and annulus  40 ) is permitted. As depicted in  FIG. 3A , the openings  76  are not aligned with the passages  72 , but instead the seals  78  straddle the passages and prevent flow between the interior and exterior of the tubular string  32 .  
         [0042]     The actuator  68  includes a member  80  which is displaced when the material  62  swells. Note that the member  80  and the sleeve  74  may be integrally formed or otherwise constructed to perform their respective functions.  
         [0043]     The actuator  68  also includes ports  82  which provide for contact between the material  62  and fluid in the annulus  40  exterior to the tubular string  32 . Note that the ports  82  could alternatively, or in addition, be positioned to provide for contact between the material  62  and fluid in the passage  58  on the interior of the tubular string  32  (similar to the ports  66  described above).  
         [0044]     The fluid (e.g., hydrocarbon liquid, water, gas, etc.) which contacts the material  62  to cause it to swell may be introduced at any time. The fluid could be in the well at the time the well tool  20  is installed in the well. The fluid could be flowed into the well after installation of the well tool  20 . For example, if the fluid is hydrocarbon fluid, then the fluid may contact the material  62  after the well is placed in production.  
         [0045]     Although the well tool  20  is described above as being opened after installation in the well and after contact with an appropriate fluid for a sufficient amount of time to swell the material  62 , it will be readily appreciated that the well tool could be readily modified to instead close after installation in the well. For example, the relative positions of the openings  76  and seals  78  on the sleeve  74  could be reversed while the position of the ports  70  could be such that they initially align with the openings, and then are sealed off after the swelling of the material  62 .  
         [0046]     Referring additionally now to  FIGS. 4A  &amp; B, a schematic cross-sectional view of an actuator which may be used for the actuators  38 ,  50  in the well system  10  is representatively illustrated. The actuator is depicted in  FIG. 4A  in a configuration in which the actuator is initially installed in the well, and in  FIG. 4B  the actuator is depicted in a configuration in which the actuator has been used to actuate a device (such as the anchoring device  48  of the well tool  18  or the sealing device  36  of the well tool  22 ). However, it should be clearly understood that the actuator depicted in  FIGS. 4A  &amp; B could be used to operate other types of devices and may be used in other types of well tools, in keeping with the principles of the invention.  
         [0047]     Those skilled in the art will appreciate that a conventional method of setting a packer or liner hanger is to apply an upwardly or downwardly directed force to a mandrel assembly of the packer or liner hanger. In  FIGS. 4A  &amp; B, a portion of a mandrel assembly  84  is depicted as being included in the actuator  38 ,  50 . This mandrel assembly  84  is displaced downwardly after installation in the well to set the sealing device  36  or anchoring device  48 . However, it will be appreciated that the mandrel assembly  84  could instead be displaced upwardly, or in any other direction, to actuate a well tool without departing from the principles of the invention.  
         [0048]     Some portions of the actuator  38 ,  50  are similar to those of the actuator  68  described above, and these are indicated in  FIGS. 4A  &amp; B using the same reference numbers. Specifically, the swellable material  62  is used to displace the member  80  and sleeve  74  relative to the passage  72 .  
         [0049]     In the embodiment of  FIGS. 4A  &amp; B, however, the passage  72  is in communication with a chamber  86  which is initially at a relatively low pressure (such as atmospheric pressure). Another chamber  88  is provided which is initially at a relatively low pressure, with a piston  90  on the mandrel assembly  84  separating the chambers  86 ,  88 .  
         [0050]     As depicted in  FIG. 4A , pressures across the piston  90  are initially balanced and there is no biasing force thus applied to the mandrel assembly  84 . However, when the material  62  swells and the sleeve  74  is displaced downwardly as depicted in  FIG. 4B , the openings  76  align with the passages  72  and the relatively high pressure in the annulus  40  enters the chamber  86 . A pressure differential across the piston  90  results, and the mandrel assembly  84  is thereby biased to displace downwardly, setting the anchoring device  48  and/or sealing device  36 .  
         [0051]     Referring additionally now to  FIGS. 5A  &amp; B, schematic cross-sectional views of the well tool  24  are representatively illustrated. The well tool  24  is depicted in  FIG. 5A  in a configuration in which the well tool is initially installed in the well, and in  FIG. 5B  the well tool is depicted after installation.  
         [0052]     The well tool  24  includes the swellable material  62  described above. However, in this embodiment, the material  62  is not used in a separate actuator for the well tool  24 . Instead, the material  62  itself is used to directly seal off a flow passage  92  which provides for fluid communication between the passage  58  and the annulus  40  (or between the interior and exterior of the tubular string  32 ).  
         [0053]     The material  62  and passage  92  are included in a flow control device  94  of the well tool  24 . As depicted in  FIG. 5A , the flow passage  92  is open and permits flow between the passage  58  and the annulus  40 . As depicted in  FIG. 5B , the flow passage  92  has been closed off due to the increased volume of the material  62  and its resulting sealing engagement between inner and outer housings  96 ,  98  of the well tool  24 .  
         [0054]     Referring additionally now to  FIGS. 6A  &amp; B, an alternate construction of the well tool  24  is representatively illustrated. In this alternate construction, the material  62  does not necessarily seal between the inner and outer housings  96 ,  98 , but when the material swells it does at least block flow through the passage  92 .  
         [0055]     Note that in this embodiment, ports  100  provide for contact between the material  62  and fluid in the annulus  40 , and ports  102  provide for contact between the material  62  and fluid in the passage  58 . Either or both of these sets of ports  100 ,  102  may be used as desired.  
         [0056]     It will be appreciated that the well tool  24  as depicted in either  FIGS. 5A  &amp; B or in  FIGS. 6A  &amp; B may be substituted for the well tool  20  as depicted in  FIGS. 3A  &amp; B, and vice versa. In addition, any of the flow control devices described above may be fairly easily converted to open instead of close after installation in the well, and any of the flow control devices may be used in the well tools  26 ,  28  if desired.  
         [0057]     Referring again to  FIG. 1 , in one unique method of using the well tool  20 , a well testing operation may be conducted using the features of the well tool. For example, flow between the zone  34  and the interior of the tubular string  32  may be initially permitted, thereby allowing for testing of the zone (for example, flow testing, build-up and drawdown tests, etc.).  
         [0058]     After sufficient contact between the material  62  and fluid in the well, the flow control device  70  will close and prevent flow between the zone  34  and the interior passage  58  of the tubular string  32 , thereby isolating the zone. Subsequent tests may then be performed on another zone (such as the zone  44 ) which is in fluid communication with the interior of the tubular string  32 , without interference due to fluid communication with the zone  34 .  
         [0059]     Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to these specific embodiments, and such changes are within the scope of the principles of the present invention. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.

Summary:
Well tools utilizing swellable materials. Actuators for well tools may incorporate swellable materials as force generating devices. A well tool includes an actuator which actuates the well tool in response to contact between a swellable material and a well fluid. A method of actuating a well tool includes the steps of: installing a well tool including an actuator; contacting a swellable material of the actuator with a well fluid; and actuating the well tool in response to the contacting step. A well system includes a well tool with a flow control device and a swellable material. The well tool is operative to control flow through a passage of a tubular string in response to contact between the swellable material and well fluid.