Patent Publication Number: US-9422792-B2

Title: Washpipe isolation valve and associated systems and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. application Ser. No. 13/474,571 filed on 17 May 2012. The entire disclosure of this prior application is incorporated herein by this reference. 
    
    
     BACKGROUND 
     This disclosure relates generally to equipment utilized and operations performed in conjunction with a subterranean well and, in an example described below, more particularly provides a washpipe isolation valve system and method. 
     Washpipes are used in well screens to deflect and direct fluid which flows inward through the well screens during, for example, gravel packing and fracturing operations. A washpipe can typically be manipulated, or pressure can be applied to operate a valve, so that flow into the well screens is prevented (e.g., in fracturing or other stimulation operations), in order to force the flow into an earth formation surrounding a well screen. 
     Therefore, it will be appreciated that improvements are continually needed in the art of constructing and operating washpipe systems. 
     SUMMARY 
     In the disclosure below, systems and methods are provided which bring improvements to the art. One example is described below in which a valve is interconnected between opposite ends of a washpipe. Another example is described below in which the valve is operated by picking up on a service tool string, thereby closing the valve and configuring the service tool string for a squeeze operation. 
     A method described below can comprise closing a valve interconnected between sections of a washpipe of a service tool string by displacing the service tool string relative to a completion string, thereby preventing flow through the washpipe. 
     In one example, a well system can comprise a service tool string reciprocably received in a completion string. The service tool string may include a washpipe received in a well screen, and a valve which selectively permits and prevents flow through the washpipe. The completion string can include a structure which closes the valve in response to displacement of the service tool string relative to the completion string. Once closed, the valve cannot be reopened in the system. 
     In another example, a method described below can comprise closing first and second valves by partially withdrawing a service tool string from a completion string, thereby preventing flow through a washpipe of the service tool string; and then opening the second valve, but not the first valve, by inserting the service tool string further into the completion string. 
     These and other features, advantages and benefits will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative examples below and the accompanying drawings, in which similar elements are indicated in the various figures using the same reference numbers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 &amp; 2  are representative partially cross-sectional views of a system for use with a well, and steps of an associated method, which system and method can embody principles of this disclosure. 
         FIG. 3  is an enlarged scale representative cross-sectional view of a portion of a completion string and a service tool string which may be used in the system and method of  FIGS. 1 &amp; 2 . 
         FIG. 4  is a representative partially cross-sectional view of the system, wherein a valve depicted in  FIG. 3  is shifted closed. 
         FIG. 5  is an enlarged scale representative cross-sectional view of the completion string and the service tool string, with the valve in its closed position. 
         FIGS. 6 &amp; 7  are representative partially cross-sectional views of the system in squeeze and reversing configurations thereof. 
     
    
    
     DETAILED DESCRIPTION 
     Representatively illustrated in  FIG. 1  is a system  10  for use with a subterranean well, and an associated method, which system and method can embody principles of this disclosure. However, it should be clearly understood that the system  10  and method are merely one example of an application of the principles of this disclosure in practice, and a wide variety of other examples are possible. Therefore, the scope of this disclosure is not limited at all to the details of the system  10  and method described herein and/or depicted in the drawings. 
     In the  FIG. 1  example, a generally tubular completion string  12  is positioned in a wellbore  14  lined with casing  16 . The casing  16  is preferably cemented, although the cement is not shown in  FIG. 1 . In other examples, the casing  16  may not be cemented (e.g., the casing could be expanded or formed in situ, etc.), or may not be used (e.g., the wellbore  14  could be uncased or open hole). 
     The completion string  12  includes a special gravel pack packer  18 , which seals off an annulus  20 . The packer  18  isolates the annulus  20  below the packer (the annulus below the packer being formed radially between the completion string  12  and the wellbore  14 ) from the annulus above the packer (the annulus above the packer being formed radially between a generally tubular service tool string  22  and the wellbore). 
     The completion string  12  also includes a closing sleeve  24  which selectively permits and prevents flow through a side wall of the completion string, one or more well screen  26  which filter fluid flowing into the completion string, and a seal stinger  30  which is sealingly received in a sump packer  32 . The packers  18 ,  32  isolate a section of the annulus  20  between them. 
     The service tool string  22  is used to convey the completion string  12  into the wellbore  14 , to set the packer  18 , and to selectively engage the completion string so that various operations can be performed. Eventually, the service tool string  22  is completely withdrawn from the completion string  12  and retrieved from the wellbore  14 , and a production tubing string (not shown) is stabbed into the packer  18  for production of fluids from the well. 
     The service tool string  22  includes a multi-position service tool  36 , a crossover  38 , a valve  40  and a washpipe  42 . The multi-position service tool  36  is of a type well known to those skilled in the art, and is used for setting the packer  18  and controlling flow between the service tool string  22  and the annulus  20  above and/or below the packer. 
     The crossover  38  directs flow between an interior of the service tool string  22  above the crossover and an exterior of the completion string  12 , and directs flow between the interior of the service tool string below the crossover and the annulus  20  above the packer  18  (via the service tool  36 ). These flows are segregated from each other in the crossover  38 , with one being generally radially directed and the other being generally longitudinally directed in the crossover. 
     The valve  40  selectively permits and prevents flow between the interior of the washpipe  42  and the crossover  38 . A suitable valve for use as the valve  40  is the ROC™ Reverse-Out Check Tool marketed by Halliburton Energy Services, Inc. of Houston, Tex. USA. 
     The valve  40  is initially open as depicted in  FIG. 1 . To close the valve  40 , the service tool string  22  can be raised sufficiently for an engagement structure  28  (such as collets, etc.) on the valve to engage an internal profile  34  in the completion string  12 . Of course, other types of valves, and other techniques for operating those valves, may be used within the scope of this disclosure. 
     The washpipe  42  receives fluid that passes inward through the well screen  26 . The washpipe  42  includes a valve  44  interconnected in the washpipe between its opposite ends. As viewed in  FIG. 1 , the valve  44  is positioned somewhat above the well screen  26 , but in other examples the valve could be positioned within the well screen or in another position. The valve  44  is used to selectively permit and prevent flow through the washpipe  42 , as described more fully below. 
     A slurry  48  (which may comprise gravel, proppant, etc.) is pumped from the surface, through the interior of the service tool string  22 , outward through the crossover  38  and closing sleeve  24 , and into the annulus  20  about the well screen  26 . The valves  40 ,  44  are both open at this point. 
     A fluid  50  portion of the slurry  48  flows from the annulus  20  inward through the screen  26 , into the washpipe  42  (with the valve  44  being open), through the open valve  40 , crossover  38  and service tool  36  to the annulus  20  above the packer  18  for circulation to the surface. In this manner, gravel  52  is deposited in the annulus  20  about the screen  26 . 
     The  FIG. 1  position of the service tool string  22  may be referred to as a “circulate” position, since the fluid  50  is allowed to circulate downward through the service tool string as part of the slurry  48 , and then back upward through the annulus  20  via the screen  26 , crossover  38 , etc. If sufficient pressure is applied, fractures  60  (see  FIG. 6 ) could be formed into the formation  58 , although the forming of fractures is not necessary in keeping with the scope of this disclosure. 
     In  FIG. 2 , the service tool string  22  has been raised relative to the completion string  12 , so that the engagement structure  28  passes upwardly through the internal profile  34 , thereby closing the valve  40 . In addition, this raised “reverse” position of the service tool string  22  exposes the crossover  38  ports to the annulus  20  above the packer  18 . 
     Relatively clean fluid  45  can now be flowed down the annulus  20  from the surface, inward through the crossover  38 , and then upward through the service tool string  22  to the surface, in order to flush any excess proppant, gravel, etc. from the system  10 . The closed valve  40  prevents the fluid  45  from being pumped down into the washpipe  42  (via the longitudinal passages in the crossover  38 ) and outward through the screen  26  into a formation  58  surrounding the wellbore  14 . 
     Referring additionally now to  FIG. 3 , a more detailed cross-sectional view of the valve  44  is representatively illustrated. The valve  44  is depicted in an open configuration in  FIG. 3 . 
     A flow passage  62  extends longitudinally through the valve  44 , but the passage is partially blocked by a bulkhead  64 . In the  FIG. 3  configuration, flow can bypass the bulkhead via openings  66  on opposite sides of the bulkhead, and an annular space  68  surrounding the bulkhead and in communication with the openings. Thus, fluid  50  can flow through the passage  62  from a lower section  42   b  of the washpipe  42 , outward through the openings  66  below the bulkhead  64 , through the annular space  68 , inward through the openings  66  above the bulkhead, and through the passage to an upper section  42   a  of the washpipe. 
     The annular space  68  is formed as an internal radially enlarged portion of an outer sleeve  70  reciprocably disposed on a mandrel  72  having the bulkhead  64  formed therein. The sleeve  70  has resilient collets  74  formed thereon, with each collet having a radially enlarged engagement structure  76  formed thereon. Other types of releasable engagement devices may be used, if desired. 
     In the  FIG. 3  example, the structures  76  are dimensioned appropriately for engagement with a structure  56  in the completion string  12 . For example, with the collet fingers  74  not biased inwardly or outwardly, the structures  76  can have an outer radius or lateral dimension which is greater than an inner radius or lateral dimension of the structure  56 . 
     In this manner, when the valve  44  is displaced upward through the structure  56  (e.g., when displacing the service tool string  22  from the  FIG. 2  reverse position to the  FIG. 4  shift position described below), the structures  76  will engage the structure  56 , thereby applying a downward biasing force to the sleeve  70 . Shear pins (not shown), or another releasable securing means, may be used to resist downward displacement of the sleeve  70  relative to the mandrel  72 , until a predetermined force level is reached, in order to prevent inadvertent displacement of the sleeve. 
     In  FIG. 4 , the system  10  is representatively illustrated with the service tool string  22  having been raised again somewhat relative to the completion string  12 . Due to this further withdrawing of the service tool string  22  from the completion string  12 , the valve  44  engages and passes through the structure  56  (such as a radially reduced profile, etc.) in the completion string, thereby closing the valve. In this configuration, flow through the washpipe  42  is prevented and, thus, flow of fluid  50  into the screen  26  is also prevented. 
     Referring additionally now to  FIG. 5 , the valve  44  is depicted after it has been displaced upwardly past the structure  56 . Note that the sleeve  70  has displaced downward relative to the mandrel  72 , due to the sleeve being biased downward by the engagement between the structures  56 ,  76  while the valve  44  displaced upward. 
     A snap ring  78  carried in the sleeve  70  can engage a groove  80  on the mandrel  72  to prevent subsequent upward displacement of the sleeve relative to the mandrel. Any other type of locking device (e.g., a body lock ring, etc.) may be used, as desired. 
     In the  FIG. 5  position of the sleeve  70 , flow through the passage  62  is prevented. The annular space  68  no longer provides for fluid communication between the openings  66  on either side of the bulkhead  64 . The valve  44  is in this closed configuration in the  FIG. 6  squeeze configuration, and in the  FIG. 7  reversing configuration, which are described more fully below. 
     In  FIG. 6 , the system  10  is depicted after the service tool string  22  has been lowered again from its  FIG. 4  shift position to its  FIG. 1  circulate position relative to the completion string  12 . In the  FIG. 6  configuration, the valve  44  has been closed. The valve  40 , however, is reopened when the engagement structure  28  thereon passes downwardly through the profile  34  when the service tool string  22  is displaced from the  FIG. 4  shift position to the  FIG. 1  circulate position. 
     The  FIG. 6  squeeze configuration allows the slurry  48  (which may comprise proppant) to be flowed outward into the formation  58  surrounding the wellbore  14 . Sufficient pressure may be applied to form fractures  60  into the formation  58 , although the forming of fractures is not necessary in keeping with the scope of this disclosure. 
     If desired, the service tool string  22  can be displaced to the  FIG. 4  shift position, and then to the  FIG. 6  squeeze position after a mini-frac test, and prior to pumping a gravel slurry into the annulus  20  about the screen  26 . A mini-frac test is an injection-falloff diagnostic test performed without proppant, before a main fracture stimulation treatment. 
     The intent, typically, is to break down the formation to create a short fracture during the injection period, and then to observe closure of the fracture system during the ensuing falloff period. Historically, these tests are performed immediately prior to the main fracture treatment to obtain design parameters (e.g., fracture closure pressure, fracture gradient, fluid leak-off coefficient, fluid efficiency, formation permeability and reservoir pressure). 
     In  FIG. 7 , The service tool string  22  is raised again relative to the completion string  12 , so that fluid communication between the interior of the service tool string above the packer  18  and the annulus  20  above the packer is permitted via the crossover  38 . Clean fluid  82  can now be reverse circulated through the annulus  20  and the interior of the tool string  22  via the crossover  38 , to thereby remove any proppant, gravel, sand, debris, etc. therein prior to retrieving the tool string to the surface. 
     The  FIG. 7  reverse position of the service tool string  22  is essentially the same as the  FIG. 2  reverse position, but in  FIG. 7  the valve  44  in the washpipe  42  is closed. However, the valve  40  is also closed in the  FIG. 7  reverse position of the service tool string  22 . In other examples, only one of the valves  40 ,  44  (or another valve) may be closed in a reversing configuration. 
     Note that the service tool string  22  can be displaced to a reversing configuration from any of the other  FIG. 1  circulate or  FIG. 6  squeeze configurations. 
     It can now be fully appreciated that significant advancements are provided to the art by the above disclosure. Note that the circulating, squeezing and reversing operations depicted in  FIGS. 1, 2, 6 &amp; 7  can be performed with minimal displacement of the service tool string  22  relative to the completion string  12 . This helps to reduce the overall length of the service tool and completion strings  22 ,  12 , which reduces costs, reduces installation time, and enhances the convenience and reliability of operations. 
     Furthermore, it is not necessary for the service tool string  22  to be inserted further into the completion string  12  when converting from the circulating configuration to the squeeze configuration, and then partially withdrawn from the completion string when converting from the squeeze configuration to the reversing configuration. Instead, the service tool string  22  is merely withdrawn somewhat from the completion string  12  to the  FIG. 4  position, and then lowered back to the circulate position (now the squeeze position), when converting from the circulating configuration to the squeeze configuration. 
     The above disclosure provides to the art a method which, in one example, can include closing a valve  44  interconnected between sections  42   a,b  of a washpipe  42  of a service tool string  22  by displacing the service tool string  22  relative to a completion string  12 , thereby preventing flow through the washpipe  42 . 
     The method can also include placing gravel  52  in an annulus  20  surrounding a well screen  26  of the completion string  12 , after closing the valve  44 . 
     Closing the valve  44  may include engaging a structure  56  of the completion string  12 . The structure  56  may comprise a radially reduced profile in the completion string  12 . 
     The displacing can include partially withdrawing the service tool string  22  from the completion string  12 . 
     The service tool string  22  may include a crossover  38  which directs flow outward from the service tool string  22 , and one of the sections  42   a,b  of the washpipe  42  can be interconnected between the crossover  38  and the valve  44 . 
     The method can include positioning the valve  44  within a well screen  26  of the completion string  12 . This positioning may be performed prior to the closing of the valve  44 . 
     The method may include closing a second valve  40  interconnected between the crossover  38  and the washpipe  42 . The second valve  40  can close in response to partially withdrawing the service tool string  22  from the completion string  12 . The second valve  40  may open in response to inserting the service tool string  22  further into the completion string  12 . 
     Also described above is a well system  10 . In one example, the system  10  can include a service tool string  22  reciprocably received in a completion string  12 , the service tool string  22  including a washpipe  42  received in a well screen  26 , and a valve  44  which selectively permits and prevents flow through the washpipe  42 . 
     The completion string  12  can include a structure  56  which operates the valve  44  in response to displacement of the service tool string  22  relative to the completion string  12 . Once closed, the valve  44  cannot be reopened in the system  10 . 
     The valve  44  may be interconnected between sections  42   a,b  of the washpipe  42 . The displacement can comprise partial withdrawal of the service tool string  22  from the completion string  12 . 
     Another method can comprise closing first and second valves  44 ,  40  by partially withdrawing a service tool string  22  from a completion string  12 , thereby preventing flow through a washpipe  42  of the service tool string  22 , then opening the second valve  40 , but not the first valve  44 , by inserting the service tool string  22  further into the completion string  12 . 
     The method can also include placing gravel  52  in an annulus  20  surrounding a well screen  26  of the completion string  12 , after closing the first valve  44 . 
     Also described above is a method of treating a subterranean well. The method can comprise: positioning a service tool string  22  in a circulate position relative to a completion string  12 , whereby a fluid  50  (e.g., included in the slurry  48 ) can be circulated from the service tool string  22  to an annulus  20  formed radially between the service tool string  22  and a wellbore  14 ; and then positioning the service tool string  22  in a squeeze position relative to the completion string  12 , whereby the fluid  50  can flow via the service tool string  22  to a portion of the annulus  20  surrounding the completion string  12 , but the fluid  50  cannot flow to a portion of the annulus  20  above the completion string  12  (e.g., above the packer  18 ). The service tool string  22  is not further inserted into the completion string  12  beyond the circulate position between the step of positioning the service tool string  22  in the circulate position and the step of positioning the service tool string  22  in the squeeze position. 
     The method can include positioning the service tool string  22  in a reverse position relative to the completion string  12 , whereby a clean fluid  45 ,  82  can be flowed from the annulus  20  into the service tool string  22 . 
     The circulate position is, in one example, at a same longitudinal position of the service tool string  22  relative to the completion string  12  as the squeeze position. 
     The service tool string  22  may be partially withdrawn from the completion string  12 , between the step of positioning the service tool string  22  in the circulate position and the step of positioning the service tool string  22  in the reverse position. 
     The method may include further withdrawing the service tool string  22  from the completion string  12  beyond the reverse position, thereby closing a valve  44  and preventing flow through a washpipe  42  of the service tool string  22 . 
     The step of positioning the service tool string  22  in the squeeze position can be performed after the step of closing the valve  44 . The service tool string  22  may be inserted further into the completion string  12 , between the step of closing the valve  44  and the step of positioning the service tool string  22  in the squeeze position. 
     The service tool string  22  may be partially withdrawn from the completion string  12 , between the step of positioning the service tool string  22  in the squeeze position and the step of positioning the service tool string  22  in the reverse position. 
     Although various examples have been described above, with each example having certain features, it should be understood that it is not necessary for a particular feature of one example to be used exclusively with that example. Instead, any of the features described above and/or depicted in the drawings can be combined with any of the examples, in addition to or in substitution for any of the other features of those examples. One example&#39;s features are not mutually exclusive to another example&#39;s features. Instead, the scope of this disclosure encompasses any combination of any of the features. 
     Although each example described above includes a certain combination of features, it should be understood that it is not necessary for all features of an example to be used. Instead, any of the features described above can be used, without any other particular feature or features also being used. 
     It should be understood that the various embodiments 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 this disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments. 
     In the above description of the representative examples, directional terms (such as “above,” “below,” “upper,” “lower,” etc.) are used for convenience in referring to the accompanying drawings. However, it should be clearly understood that the scope of this disclosure is not limited to any particular directions described herein. 
     The terms “including,” “includes,” “comprising,” “comprises,” and similar terms are used in a non-limiting sense in this specification. For example, if a system, method, apparatus, device, etc., is described as “including” a certain feature or element, the system, method, apparatus, device, etc., can include that feature or element, and can also include other features or elements. Similarly, the term “comprises” is considered to mean “comprises, but is not limited to.” 
     Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of this disclosure. For example, structures disclosed as being separately formed can, in other examples, be integrally formed and vice versa. 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 invention being limited solely by the appended claims and their equivalents.