Patent Publication Number: US-7909110-B2

Title: Anchoring and sealing system for cased hole wells

Description:
BACKGROUND 
     The invention generally relates to an anchoring and sealing system for cased hole wells. 
     A packer is a device that typically is used in a well to form an annular seal between an inner tubing string and a surrounding casing string. More specifically, the packer typically is part of the inner tubing string and contains a sealing element that is formed from one or more elastomer seal rings. The rings are sized to pass through the well when the packer is being run downhole into position, and when the packer is in the appropriate downhole position and is to be set, gages of the packer compress the seal rings to cause the rings to radially expand to form the annular seal. A number of different mechanisms may be used to develop the force to radially expand the seal rings, such as hydraulically, weight set or electrically actuated mechanisms. 
     Other types of packers may include sealing elements that are set without using a compressive force. For example, a packer may have an inflatable bladder that is radially expanded to form an annular seal using fluid that is communicated into the interior space of the bladder through a control line. As another example, a packer may have a swellable material that swells in the presence of a well fluid or other triggering agent to form an annular seal. 
     SUMMARY 
     In an embodiment of the invention, an apparatus includes a casing and a sealing element that is retained in the casing. The sealing element has an unset state in which the sealing element has a first radial thickness and a set state in which the sealing element has a second radial thickness that is greater than the first radial thickness to form a seal between the casing and an inner tubular member. 
     In another embodiment of the invention, a method that is usable with a well includes providing a sealing element that has an unset state in which the sealing element has a first radial thickness and a set state in which the sealing element has a second radial thickness that is greater than the first radial thickness to form a seal between a casing and an inner tubular member. The method includes retaining the sealing element in the casing. 
     In yet another embodiment of the invention, a system includes a casing, a sealing element that is retained in the casing and a tubular member that is located inside the casing. The tubular member is adapted to deform against the sealing element to form a seal between the tubular member and the casing. 
     Advantages and other features of the invention will become apparent from the following drawing, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIGS. 1 and 2  are schematic diagrams of a well showing different states of an anchoring and sealing system according to an embodiment of the invention. 
         FIG. 3  is a partial cross-sectional diagram taken along line  3 - 3  of  FIG. 1  according to an embodiment of the invention. 
         FIGS. 4 ,  5 ,  6 ,  7 ,  8  and  9  are illustrations of different profiles on the inside of the casing string according to different embodiments of the invention. 
         FIGS. 10 ,  11  and  12  are views of casing strings sections illustrating slot patterns on the inside of the casing string according to different embodiments of the invention. 
         FIGS. 13 ,  14  and  15  are partial cross-sectional views of other compression-type anchoring and sealing systems according to other embodiments of the invention. 
         FIG. 16  is a cross-sectional view of an exemplary plug of  FIG. 15  according to an embodiment of the invention. 
         FIGS. 17 and 18  are partial cross-sectional views of an anchoring and sealing system formed from a deformable sleeve according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments are possible. 
     As used here, the terms “above” and “below”; “up” and “down”; “upper” and “lower”; “upwardly” and “downwardly”; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the invention. However, when applied to equipment and methods for use in wells that are deviated or horizontal, such terms may refer to a left to right, right to left, or diagonal relationship as appropriate. 
     Referring to  FIGS. 1 and 2 , an embodiment b  10  of a well (a subterranean or subsea well) in accordance with the invention includes a casing string  22  that lines and supports a wellbore  20 . Unlike conventional arrangements, the casing string  22  has a built-in anchoring and sealing system  40  for purposes of forming an annular seal (as shown at reference numeral  60  in  FIG. 2 ) between the interior surface of the string  22  and the outer surface of an inner tubular member  36 . More specifically, the system  40  has a settable annular sealing element  60  and anchoring features that take the place of a conventional packer.  FIG. 1  depicts the system  40  in an unset state, a state in which the annular seal has not been formed. When the system  40  receives an actuating force (as described below), the system  40  radially expands the sealing element  60  to form the annular seal, as depicted in  FIG. 2 . The inclusion of the sealing and anchoring components in the casing string  22  is to be contrasted to conventional arrangements in which the tubular member  36  may be part of a packer or plug (as examples). 
     As a more specific example, the tubular member  36  may be part of a tubular string  30  (a work string, production tubing string, test string, etc.), which extends downhole inside the casing string  22 . The tubular string  30  may include, as further described below, a setting, or service tool (not shown in  FIGS. 1 and 2 ), which delivers a setting force that the system  40  communicates to the sealing element  60  to cause the element  60  to transition from a first radial thickness to a second thicker radial thickness to form the annular seal, as depicted in  FIG. 2 . 
     Among its other features, the system  40  includes a locking mechanism for purposes of maintaining the sealing element in its set state, and the system  40  is also constructed to anchor the seal in place. Thus, dogs, or slips, a conventional component of packers, are not required. 
     The advantages of a system that includes a casing, which retains and anchors an annular sealing element may include one or more of the following. The design of the sealing element is greatly simplified, as compared to, for example, the design of a packer&#39;s sealing element. The design of the setting/service tool is simplified. The pressure and temperature rating of the system  40  may be significantly higher than conventional sealing devices (e.g., packers) due to the presence of both multiple seal surfaces and the capturing of the sealing element in a groove, in specific embodiments that are further described below. Thus, the system  40  may be well-suited for high pressure high temperature (HPHT) applications. As described below, the sealing element may be protected in some embodiments of the invention, as opposed to conventional packer designs where the sealing element is exposed to swabbing/abrasion during the running of the element into place in the well. High strength casing strings (e.g., casing strings for HPHT applications) may be used due to the elimination of the slips, which tend to “bite” into the casing string. 
     As a more specific example,  FIG. 3  depicts a partial cross-sectional view of the anchoring and sealing system  40  in accordance with some embodiments of the invention. In particular,  FIG. 3  depicts a right-hand cross-sectional view of the system  40  taken about its longitudinal axis  100  and along line  3 - 3  of  FIG. 1 . The longitudinal axis  100  is coaxial with the tubular string  30  and the tubular member  36  (see  FIGS. 1 and 2 ) near the system  40 . As can be appreciated by one of skill in the art, the true cross-section of the system  40  taken alone line  3 - 3  of  FIG. 1  also includes a mirroring left-hand cross-section on the left-hand side of the longitudinal axis  100 , as the system  40  is generally symmetrical about the axis  100 . 
     As depicted in  FIG. 3 , the system  40  includes an annular sealing element  60  and a section  22   a  of the casing  22 , which contains an inner profile  46  that is designed to both retain and anchor the annular sealing element  60  in place. For the embodiment that is depicted in  FIG. 3 , the inner profile  46  includes an annular slot  50 , which is formed in the inner surface of the casing section  22   a  and retains the annular sealing element  60 . At the bottom of the slot  50 , the casing section  22   a  contains a “no go” shoulder  51 , which provides a longitudinal stop for purposes of setting the sealing element  60 . In this regard, when the system  40  receives a setting force from a service/setting tool  70  to expand the sealing element  60 , the force is communicated to a setting ring  65  that is located in the slot  50 , secured to the tubular member  36 , and is disposed at the top of the sealing element  60 . 
     More specifically, when the sealing element  60  is set, a downward axial force is applied to the setting ring  65 , which causes the ring  65  to move in a downward direction and communicate a corresponding compression force across the sealing element  60  to thereby cause the element&#39;s radial expansion. In its fully radially expanded state (i.e., in its set state), the sealing element  60  forms the annular seal between the interior surface of the casing  22  and an exterior surface  96  of the inner tubular member  36 . 
     As examples, the inner tubular member  36  may be a mandrel, or sleeve, that is connected to a lower completion  94 . As a more specific example, the lower completion  94  may be a circulation valve, although other tools and/or lower completions are contemplated in other embodiments of the invention. During the expansion of the sealing element  60 , the tubular member  36  moves downwardly, a movement that may be used to actuate a tool of the lower completion  94  (to open a circulation valve, for example). 
     The downward axial force that is used to set the sealing element  60  is derived from, as an example, a collet sleeve  72  of the service/setting tool  70  in accordance with some embodiments of the invention. More particularly, as further described below, the collet sleeve  72  engages a profile  74  of the tubular member  36  to exert a downward force on the setting ring  65  for purposes of radially expanding the sealing element  60 . 
     As also depicted in  FIG. 3 , in accordance with some embodiments of the invention, the casing section  22   a  includes a lower inner annular shoulder  80 , which forms a “no go” shoulder for purposes of engaging a corresponding outer shoulder  82  of the tubular member  36  to limit the member&#39;s downward travel. Additionally, as further described below, a ratchet mechanism (not shown in  FIG. 3 ) locks the axial position of the setting ring  65  to maintain the sealing element  60  in its set state. 
     Among its other features, in accordance with some embodiments of the invention, the system  40  includes a protective covering  51 , which may, as depicted in  FIG. 3  be disposed on and protect the inner surface of the sealing element  60 . The protective covering  51  temporarily protects the sealing element  60  from operations that occur inside the casing string  22 , such as cementing operations, for example. More specifically, the protective covering  51  may protect the sealing element  60  from swabbing, abrasion or any other downhole operation that may damage the sealing element  60 . The protective covering  51  may be temporary in nature and may be made from a dissolvable/frangible material or any other material that is reactive or starts communicating fluid over a period of time. For embodiments of the invention in which the sealing element  60  is made from a swellable material, the protective covering  51  may be permeable or porous material or any other material that gradually absorbs fluid from the surrounding environment. 
     Depending on the particular embodiment of the invention, the sealing element  60  may include a sealing material  52 , such as any of the following: rubber, including swellable and wire reinforced rubber; polymers, thermoplastics (Teflon®, for example); thermosets (epoxies, for example); metals; alloys (deformable, elastic and plastic); alloy composites and non-metals (graphite, expanded graphite, etc.), as just a few examples. The sealing element  60  produces any type or combination of types of sealing, such as rubber-to-rubber, rubber-to-metal, metal-to-metal, rubber-to-non-metal, non-metal-to-non-metal seals, etc. 
     Although not depicted in  FIG. 3 , the casing  22  may include one or more expansion joints to compensate for thermal expansion or tubing movement for purposes of more efficiently aligning the service tool to the setting ring  65 . 
     The inner profile  46  of the casing section  22   a  may take on a number of different forms, depending on the particular embodiment of the invention. For example,  FIGS. 3 and 4  (a cross-sectional view) depicts the profile  46  as containing the single annular groove  50 . However, in accordance with other embodiments of the invention, the system  40  may include multiple grooves, which each groove housing a corresponding sealing element and setting ring. For example,  FIG. 5  depicts another profile  102 , which includes multiple grooves  50 . 
     The grooves  50  may have cross-sections other than square cross-sections in accordance with other embodiments of the invention. In this regard,  FIG. 6  depicts an alternative profile  104 , which includes multiple grooves  120 , that have beveled surfaces.  FIG. 7  depicts an alternative in an alternative profile  106  that includes dovetail-shaped grooves  124 . As yet other variations,  FIG. 8  depicts an alternative profile  108  that includes grooves  130  that have triangular cross-sections; and  FIG. 9  depicts an alternative profile  110  that includes grooves  134  that have rounded grooves  134 . Thus, many variations are contemplated and are within the scope of the appended claims. 
     In other embodiments of the invention, the above-described grooves may be replaced by recessed regions that do not individually extend completely around the longitudinal axis  100  in the inner surface of the casing string  22 . Each region may contain a sealing element and setting ring, for example. More specifically,  FIG. 10  depicts an arrangement in accordance with some embodiments of the invention in which the inner surface of the casing string section  22   a  includes square recesses  150  that are arranged in a particular pattern around the longitudinal axis  100 . As another variation,  FIG. 11  depicts a pattern  160  of pentagon-shaped slots in the casing section  22   a . As yet another variation,  FIG. 12  depicts a pattern  170  of triangular-shaped slots in a diamond pattern. Thus, many variations are possible and are within the scope of the appended claims. 
       FIG. 13  depicts a partial cross-sectional view of the anchoring and sealing system  40  and an associated service tool that is used to set the sealing element  60  in accordance with some embodiments of the invention. More specifically, for this example, the casing section  22   a  includes the annular groove  50 , which contains the setting ring  65  and the sealing element  60 . As shown in  FIG. 13 , the setting ring  65  includes ratchet teeth  204  that engage corresponding ratchet teeth  200  that are formed on the interior surface of the casing section  22   a  inside the slot  50 . Thus, the axial position of the setting ring  65  is maintained due to this ratchet mechanism. 
     For this example, the collet sleeve  74  of the service tool includes a radial extension  74   a  that extends in a radially outward direction to mate with a corresponding annular groove  65   a  of the setting ring  65 . When these two components engage, downward movement of the collet sleeve  74  causes corresponding downward movement of the setting ring  65  to set the sealing element  60 . As depicted in  FIG. 13 , the mandrel or sleeve  90  is connected to the collet sleeve  74  for purposes of actuating a downhole tool. 
     As another variation,  FIG. 14  depicts a partial cross-sectional view of the system  40  and a service/setting tool  260  according to another embodiment of the invention. In this arrangement, the casing string section  22   a  includes an annular recessed region  240  that receives the sealing element  60  and a setting ring  230 . As shown, the setting ring  230  is radially positioned to act on the sealing element  60  to push the sealing element  60  against a lower “no go,” or annular shoulder  242 . The setting ring  230  includes an annular groove  232  that receives a split lock ring  234  (such as a C-ring, for example). The service/setting tool  260  engages the top of the setting sleeve  250  and moves it downward. The setting sleeve  250  in turn engages the top of the setting ring  230  and moves it downwards to compress the sealing element  60  at the same time. Sealing element  60  when fully expanded seals against the outer surface of the sleeve  250 . At the same time, the split lock ring  234  aligns with a groove on the outer surface of the sleeve  250  and pops open to lock the sleeve  250  with the setting ring  230 . A ratchet (not shown in  FIG. 14 ) locks the position of the setting ring  230  and thus, maintains the position of the sealing element  60 . The sleeve  250  may be connected to a lower completion, in accordance with some embodiments of the invention. 
       FIG. 15  depicts a partial cross-sectional view of the system  40  and service tool in accordance with yet another embodiment of the invention. In this arrangement, the sealing element  60  resides inside an annularly recessed region  314  of the casing section  22   a . Downward movement of the sealing element  60  is limited by a “no go,” or lower, inner annular shoulder  302  of the casing section  22   a . The compression of the sealing element  60  is provided by a piston  310 , that has a position that is lockable by a ratchet mechanism  324  and  326 . 
     The system also includes a tubular member, such as a sleeve  340 , which actuates a lower completion, for example. The sleeve  340  is adjacent to the outer surface of the sealing element  60  and includes a passageway  373  for purposes of establishing fluid communication between the piston  310  and the inner passageway of the casing string  22 . In this regard, a plug  370  blocks communication between the interior of the sleeve  340  and the longitudinal passageway  373 . When a radial port  354  of a setting sleeve  350  of the service tool is generally aligned with the plug  370 , a sealed communication space  371  exists. Fluid communication pressure may then be applied through the tubing string that contains the service tool to exert fluid pressure on the plug  370  for purposes of removing the plug  370 . Upon this occurrence, fluid communication is established between the tubing string&#39;s central passageway and the piston  310  for purposes of producing a downward force on the piston  310  to set the sealing element  60 . 
     The plug  370  may take on numerous forms, depending on the particular embodiment of the invention. As examples, the plug  370  may be an e-trigger, a shearable plug, a burst disc, etc. As a more specific example,  FIG. 16  depicts an embodiment of the plug  370  in accordance with some embodiments of the invention. In this embodiment, the plug includes a sealing surface  392  that forms a barrier between the space  371  ( FIG. 15 ) and the central passageway of the tubing string. The plug  370  is generally formed, such as by way of an annular notch  394 , to rupture at a predetermined pressure threshold or shear by a predetermined mechanical force to establish fluid communication to drive the piston  310 . 
     As yet another variation,  FIG. 17  depicts an embodiment in which a deformable sleeve  410  is used to form a seal between an annular sealing element  404  that is disposed in an annular groove  400  inside the casing string section  22   a . In this regard, the sleeve  410  is disposed on the inner surface of the sealing element  404 . Referring also to  FIG. 18 , when a seal is to be formed between the sleeve  410  and the casing section  22   a , the sleeve  410  is deformed, which causes its radial expansion (as shown in  FIG. 18 ). As examples, the radial force on the sleeve  410  may be exerted by thermal expansion, magnetic fields, heat from a chemical reaction, etc., depending on the particular embodiment of the invention. 
     While the present invention has been described with respect to a limited number of embodiments, those skilled in the art, having the benefit of this disclosure, will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.