Abstract:
Disclosed is a workstring for use in a gravel packing system. The workstring includes a washpipe with at least one port and a selectively openable and closeable closure mechanism in operable communication with the at least one port. 
     Further disclosed is a collet having a collet base and a plurality of collet fingers extending from the collet base. At least one of the collet fingers includes retaining feature, the retaining feature being configured to yield under bending at a selected valve. 
     Yet further disclosed is a method for gravel packing. The method includes gravel packing a wellbore including opening one or more valves in a washpipe as pressure associated with the gravel packing climbs, the valves providing an escape path for a fluid component of the gravel pack to an inside dimension of the washpipe. The method further includes closing the one or more valves in the washpipe.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of an earlier filing date from U.S. Ser. No. 60/530,852 filed Dec. 18, 2003, the entire contents of which is incorporated herein by reference. 

   BACKGROUND 
   In the hydrocarbon recovery industry, gravel packs have longed been used to help prevent unconsolidated formations from collapsing and occluding a borehole therein while also filtering some of the granular material that would otherwise be entrained with the desired production fluid. As wellbore technology is developed, allowing for multilateral well systems, including highly deviated and even horizontal systems, the hydrocarbon industry has had increasing interest in creating horizontal gravel packs for similar reasons as their vertical predecessors were employed. In some cases, such horizontal gravel packs are extremely long. While the pack itself is still quite capable of performing as intended, an issue presents itself with respect to the formation. When an extremely long gravel pack is created, the fluid pressure developed and applied at surface that is required to continue the gravel packing operation as the pack gets longer and longer is continually higher. At a point, such pressure will be damaging to the formation, which is undesirable. Therefore, it has been discovered that it is desirable to create an auxiliary valve system which shortens the escape path of the gravel pack fluid thereby reducing the overall pressure required to complete the packing operation. A device and method to accomplish shortening of such path is disclosed in U.S. Pat. No. 6,311,772 to Myhre et al. and owned by the assignee hereof, Baker Hughes Incorporated, Houston, Tex. That device functions extraordinarily well for its intended purpose and does indeed reduce pressures substantially, and to well below levels associated with problems for the formation. Unfortunately, however, the device described in the &#39;772 patent also leaves a washpipe that is not capable of conveying fluids to the bottom of the well because it has in general, a plurality of now open valves over its length, those valves having been opened sequentially by pressure activation to shorten the escape path for the gravel pack slurry fluid. Since it is often desirable to provide to the downhole most end of the workstring a stimulation fluid and operator is required to pull the workstring and in another run provide a device capable of conveying the stimulation fluid to the desired location. As one of ordinary skill in the art is all too well aware, additional runs dramatically increase costs of an operation and therefore are to be avoided. A tool capable of providing for a stimulation operation while avoiding the secondary run after the gravel packing operation would certainly be well received by the art. 
   SUMMARY 
   Disclosed herein is a workstring for use in a gravel packing system. The workstring includes a washpipe with at least one port and a selectively openable and closeable closure mechanism in operable communication with the at least one port. 
   Further disclosed herein is a collet having a collet base and a plurality of collet fingers extending from the collet base. At least one of the collet fingers includes retaining feature, the retaining feature being configured to yield under bending at a selected value. 
   Yet further disclosed herein is a method for gravel packing. The method includes gravel packing a wellbore including opening one or more valves in a washpipe as pressure associated with the gravel packing climbs, the valves providing an escape path for a fluid component of the gravel pack to an inside dimension of the washpipe. The method further includes closing the one or more valves in the washpipe. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
       FIGS. 1A-1E  are an extended view in cross-section and quarter section of a workstring for a gravel packing operation, the workstring in a run-in position; 
       FIGS. 2A-2B  are an extended view of a portion of the workstring of  FIGS. 1A-1E  in a locating position; 
       FIGS. 3A-3B  are an extended view of a portion of the workstring of  FIG. 1A-1E  in a position for shifting a closing sleeve; 
       FIGS. 4A-4B  are an extended view of a portion of the workstring of  FIG. 1A-1E  in a partial closure operation; 
       FIGS. 5A-5B  are an extended view of a portion of the workstring of  FIG. 1A-1E  with ports closed and collet restricted; 
       FIGS. 6A-6C  are a family of depictions of the same components in progressive stages of activation; 
       FIG. 7  is a side view of a collet as described herein; 
       FIG. 8  is a side view of a ported mandrel divorced from other components; 
       FIG. 9  is a side view of a ported connector divorced from other components; 
       FIG. 10  is a side view of a closing sleeve divorced from other components; 
       FIG. 11  is a side view of a ported housing divorced from other components; 
       FIG. 12  is an enlarged view of a collet finger retaining feature in situ. 
   

   DETAILED DESCRIPTION 
   In the following detailed description applicants have elected to describe the interconnection of all of the various components of this tool prior to discussing its operation. It is believed that once the components are identified the operation of the tool will be much more easily understood by one of ordinary skill in the art. It is important to point out that in the drawings only one pressure actuated valve and one closure mechanism are illustrated as part of the tool. One or more of these valves and closure mechanisms are contemplated as desired or needed for particular applications. 
   For the identification portion of this application, reference to  FIGS. 1A-1E  will be sufficient. Additional reference to  FIGS. 7-11  may be helpful. The tool  10  comprises a top sub  12  which is connected to a ported mandrel  14  at thread  16  and is sealed thereto by o-ring or other suitable seal  18 . The ported mandrel includes ports  20  which are utilized to shorten the escape route of gravel slurry fluid as noted above. These ports are selectively used as will be discussed further hereinafter. Also connected to top sub  12  is a ported housing  22  having ports  24  which are aligned with mandrel ports  20  at all times during operation of this tool. Ported housing  22  is fixed connected to the top sub  12 . A collet spring  26  bears against top sub  12  and against collet which collet includes a plurality of fingers  30 , each of which has a plurality of features. More specifically, fingers  30  include a back angle  32  for engagement with the ported mandrel and recess  34  at the appropriate time. Further, fingers  30  include a pair of wings  36  functioning to allow passage at a certain time through other components of the tool and to maintain the tool in the locked position at other times during its operation. Finally, each finger  30  includes a closing feature  38  and a position retaining feature  40 . A ported connector  42  is slidably received adjacent collet  28  and ported mandrel  14  in a position radially outward of each of those components. The ported connector  42  includes ports having specific opening configurations to ensure appropriate movement of collet  28 . These ports include (see  FIGS. 6A ,  9  and  12 ) restrictive port  44  and opening port  46  where restricted port  44  is sized more narrowly than the outside dimension of wings  36  of collet fingers  30  and wherein opening port  46  is sufficiently large to allow passage of wings  36  through port  46 . The ported connector  42  is connected via threaded connection  48  to opening sleeve  50 . The opening sleeve  50  includes ports  52  and a plurality of o-ring seal grooves  54 . The opening sleeve  50  is shear screwed to piston stop  56  at shear screw  58 . Due to the proximity of the closing sleeve  60 , it is appropriate to mention it now. The closing sleeve is defeatably retained by such as a shear member e.g., shear screw  62  to the ported housing  22 . 
   At a downhole end of opening sleeve  50 , that sleeve is threadedly connected at thread  64  to a piston mandrel  66  which mandrel includes a port  68 . The mandrel further includes a way for a dog  70 , which will snap out of engagement with an upper mandrel  72  at recess  77 , to free a number of components to move downhole as will be described hereinafter. The dog  70  is initially maintained in contact with the upper mandrel  72  by a piston  74  which is pressure moveable against a piston spring  76 . It is noted that piston  74  includes seal grooves  78 . At a downhole end of piston mandrel  66 , the mandrel is threadedly connected at thread  80  to a cap  82 , which cap bounds spring  76  at an uphole end of piston mandrel  66  where it abuts opening spring  84  which is bounded at its uphole end by friction bearing  86 . Friction bearing  86  is maintained in position by upper housing  88  which is connected to the ported housing  22  at its respective uphole end. At the downhole end of the upper housing  88  is connected a piston housing  90 . At the downhole end of piston housing  90 , the housing is sealed to an adapter sub  92  at a seal  94 . At the downhole end of the adapter sub  92  that sub is connected via threaded connection  96  to a spacer seal sub  98  and further includes on the adapter sub, a bonded molded seal or other suitable seal  100 . Spacer seal sub  98  is also sealed to adapter sub by seal  102 . Previously mentioned upper mandrel  72  extends downhole to a threaded connection  104  and seal  106  with a lower mandrel  108  while spacer seal sub  98  includes at a downhole end thereof a bonded molded seal or other appropriate seal  110  and a threaded connection  112  and seal  114  which connects the spacer seal sub  98  to another spacer seal sub  116 . At the downhole end of the second spacer seal sub  116  is in another seal which may be a bonded molded seal as in seal  110 , that seal being identified by numeral  118 . Spacer seal sub  116  is threadedly connected by thread  120  to bottom cap  122 . Bottom cap  122  includes a port  125  open to annulus pressure. The port  125  is also in fluid communication with a passage  123  which extends uphole in the tool to a downhole end of piston  74 . The bottom cap  122  is threadedly connected at thread  124  to lower mandrel  108  which itself is connected at a downhole end via thread  126  to a bottom sub  128 . It is noted that a seal is provided at  130  between the lower mandrel  108  and the bottom sub  128 . 
   Operation 
   Each of the components of the device having been identified, the operation of this device will now be described with reference to all figures. It is noted that initial operation of this device is similar to that disclosed in the above-identified &#39;772 patent in that the first action of this tool is caused by a pressure rise due to the gravel packing operation. The pressure rise is “seen” at piston  74  at an uphole end thereof while a downhole end thereof “sees” pressure near the bottom of the tool through passage  123  and port  125 , the piston  74  is urged against the biasing force of spring  76  in a downhole direction. Upon sufficient movement of piston  74  in the downhole direction, piston  74  will uncover dog  70  which then due to its construction will expand radially outwardly thereby removing it from contact with upper mandrel  72  at recess  77 . 
   Once dog  70  has expanded out of contact with the groove in upper mandrel  72  there is nothing preventing the opening spring  84  from urging piston mandrel  66  downhole along with opening sleeve  50 , and ported connector  42  due to the impetus of opening spring  84 . This movement also allows collet spring  26  to urge the collet  28  downhole to drive the collet ramp  33  up ported mandrel incline  35  thereby driving each of the collet fingers  30  radially outwardly of their original position (note  FIGS. 1B and 2B ). It is noted that the relative position of the ported connector  42  and the collet fingers  30  is important to functionality of the tool due to the ports  44  and  46  as above described. In this condition, the ports  52  are now aligned (note distinction between FIGS.  1 B and  2 B- 5 B) with ports  20  from the ported mandrel  14  and  24  in the ported housing  22  thereby allowing fluid flow through the tool from an annular position proximate the gravel pack to the inside dimension of the tool  10 . This is the shortened escape path for the fluid portion of the gravel slurry discussed hereinbefore. When the gravel packing operation is complete, it will then be desirable to close the through port  24 ,  52 ,  20  to the inside dimension of the tool. This operation relies upon closing sleeve  60  and the position retaining feature  40  of collet fingers  30 . As is schematically illustrated in  FIG. 3B , the position retaining feature  40  is sufficiently outwardly displaced by ramp  33  that the outside dimension of position retaining feature  40  is too large to fit through the seal bore restriction  127 . Therefore, an uphole pull on tool  10  will move all components in the uphole direction that are not prevented from moving by position retaining feature  40 . Those components prevented from moving by position retaining feature  40  include collet  28  and closing sleeve  60 . Further pull in the uphole direction will cause the shear member, such as shear screw  62 , to shear (note  2 B and  3 B) thereby allowing the closing sleeve  60  to close the ports  24 ,  52  and  20 . While it is, in appearance, that the closing sleeve  60  is moving downhole in order to close these ports it is important to recognize that in fact the closing sleeve  60  is staying in position and the rest of the tool is moving uphole, the relative displacement of the items being identical. Before the full intended stroke in the uphole direction of the balance of the tool the downhole end of the closing sleeve  60  comes in contact with piston stop  56  (see  FIG. 4B ) and loads shear screw  58 . At a selected load the shear screw  58  will shear allowing piston stop to move (See  FIG. 5B ) relative to the tool along with closing sleeve  60  such that as the tool moves uphole closing sleeve  60  and piston stop  56  are stationary. The relative downhole movement of closing sleeve  60  relative to opening sleeve  50  allows seal  54  to come in sealing engagement with closing sleeve  60 , thus sealing closed ports  52 . Following piston stop  56  and closing sleeve  60  reaching a final position, the movement of the ported mandrel  14  will have been sufficient to locate recess  34  directly radially inwardly of collet  FIG. 30  allowing the collet fingers to snap back into an unactuated condition and to engage back angle  32  with the ported mandrel  14  (note distinction  FIGS. 4B and 5B ). This locked position enables two things, the first being that the closing sleeve  60  is locked closed and cannot be accidentally opened, and secondly that because the outside dimension of the collet fingers has now been retracted the workstring may be withdrawn from the wellbore. 
   It is important to note that the collet fingers  30  are designed specifically to yield in bending, stretching, breaking, shearing, etc. at a selected load greater than required for normal operation so that in the event debris becomes positioned radially inwardly of the fingers while they are expanded in their radial outward position the entirety of tool  10  will not be stuck in the hole requiring a major recovery effort. Rather, because the collet fingers are designed to yield as stated the workstring may be removed from the downhole environment even if the collet fingers do not snap back as they are intended to do. A pull from uphole will be sufficient to yield the collet fingers before damage to other components would result. 
   In the position in which the tool sits on conclusion of the foregoing discussion ( FIGS. 5A-5B ), it is ready to circulate a stimulation fluid to the bottom hole as all of the one or more flow ports that exists in the workstring are no longer open. One additional advantage of this system is that because the ports are all closed, the workstring does have pressure integrity and is therefore capable of inflating inflatables at the downhole end such as external casing packers, or any other function requiring applied hydraulic pressure, if desired. 
   While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.