Abstract:
A shifting tool having a release mechanism of predictable deforming radial character. The tool may be utilized for activating any of a variety of different types of downhole actuators. Once more, due to the controlled and predictable manner of deformation employed in the release mechanism, load pulls directed at the actuator may be significant without undue concern over unintended or uncontrolled tool breakage. So, for example, a stuck actuator arm engaged with the shifting tool may be safely pulled at substantially greater loads thereby increasing the odds of dislodging. Thus, the occurrences of added follow-on interventional applications addressing stuck actuator arms may be reduced, resulting in tremendous time and cost savings.

Description:
PRIORITY CLAIM/CROSS REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This Patent Document claims priority under 35 U.S.C. §119 to U.S. Provisional App. Ser. No. 61/495,711, filed on Jun. 10, 2011, and entitled, “Collet Based Shifting Tool”, incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. In recognition of these expenses, added emphasis has been placed on efficiencies associated with well completions and maintenance over the life of the well. By the same token, offshore wells along with those of ever increasing depths and sophisticated architecture have emerged. Thus, added levels of complexity in terms of completions and maintenance have become fairly commonplace. 
         [0003]    In terms of basic architecture, the terminal end of a cased well often extends into an open-hole lateral leg section. Such architecture may enhance access to the reservoir. At the same time, however, this basic architecture presents certain challenges when it comes to their completions and maintenance. For example, a variety of hardware may be installed near and above the lateral leg before production through the leg is commenced. Additionally, perforating, fracturing, gravel packing and a host of other applications may be directed at the leg in advance of production. 
         [0004]    In order to carry out the different completions tasks, a formation isolation valve may be present at the juncture between the noted leg and cased regions thereabove. This valve may help to ensure a separation between completion and production fluids. More specifically, comparatively heavier fluids utilized during completions may be prone to adversely affect the formation if allowed to freely flow to the production region of the leg. By the same token, production of lighter high pressure fluids into the main bore during hardware installations may adversely affect such operations. By way of a more specific example, the leg may be outfitted with a formation isolation valve that is opened for gravel packing and other early stage leg applications. However, such a valve may be subsequently closed to isolate the open-hole portion of the leg as other completions tasks are carried out uphole of the leg. 
         [0005]    As indicated, closing the valve may avoid fluid loss during completions operations and also maintain well control in the sense of avoiding premature production of well fluids. This closure may be achieved in conjunction with removal of application tools from the open-hole region of the leg. So, for example, following a gravel packing application in a lateral leg, a shifting device incorporated into the gravel packing wash pipe may be used to close off the valve as the assembly is removed from the area. Thus, completion of the application and retrieval of the tool involved may be sufficient to close the formation isolation valve. 
         [0006]    Unfortunately, in certain circumstances, the valve may become stuck, thus, preventing retrieval of the tool and assembly as described above. Thus, continued pull on the assembly could potentially result in a breakage that might lead to a host of complications ranging from tool damage to expenses and delays associated with follow-on retrieval operations. Therefore, to avoid such complications, the shifting tool is generally configured with emergency release capacity as noted below. 
         [0007]    The valve shifting tool works to shift open the formation isolation valve by interlocking engagement with a matching profile of the valve. More specifically, the tool engages a mandrel of the valve such that upon removal of the assembly, the mandrel is pulled uphole so as to close the valve. However, the engagement portion of the tool is configured for emergency release as noted above for circumstances where the valve has become stuck. So, for example, once a predetermined amount of uphole force has been exerted, and yet the mandrel remains stuck in place, the engagement portion of the tool may deflect out of engagement with the mandrel. More specifically, where 2,000 lbs. to 5,000 lbs. of force has been exceeded without mandrel shifting, the noted deflection will occur and the assembly will be safely removed from the well. In this manner, the tool may be retrieved from the valve and visually assessed at surface for any damage during the emergency release. However, as detailed further below, no such visual inspection or quick remedy is available for assessment and/or repair of the valve which is disposed far downhole. 
         [0008]    As indicated, the described deflection and removal of the assembly avoids complications that might otherwise result from a broken tool. Unfortunately, however, this deflection and removal of the assembly still leaves an open formation isolation valve at the junction of the cased and open-hole well regions. Thus, for all intents and purposes the valve fails to achieve its intended use in terms of isolation. Further, as the typical emergency release process is likely to result in damage to the valve, it must be assumed that the valve is damaged such that typical work over remedies (e.g. flushing or circulating fluid to remove debris) will be ineffective in remedying the valve state. As a result, this means that another set of complications is now introduced. Namely, costly delays and expenses associated with the introduction of alternate interventions directed at the valve or new isolation techniques to compensate for valve failure will now likely be introduced. 
         [0009]    Once more, even though the tool, in theory, may be constructed of materials capable of withstanding load pull far in excess of 5,000 lbs., deflection is generally set to take place at such relatively low thresholds. This is due to the fact that the engagement between the tool and the mandrel is of a multi-member or ‘collet’ variety which can result in a substantially uneven distribution of radial forces during the singularly upward pull. Therefore, as a practical matter, lower thresholds are presently required to prevent breakage of any individual collet member where such a deflection technique is employed for the emergency release. Therefore, as a practical matter, lower thresholds are presently required to prevent breakage or significant damage of any individual tool collet member where such a deflection technique is employed for the emergency release. This is particularly the case in light of added concerns over the effect such breakage may have on the valve as well. 
       SUMMARY 
       [0010]    A shifting tool is detailed for releasable engagement with an actuator. The tool includes a collet element with engagement and base portions having substantially greater thicknesses than that of a central region disposed therebetween. Thus, a predictable deformation of the region may ensue upon exposure to a given load. Of course, this summary is provided to introduce a selection of concepts that are further described below and is not intended as an aid in limiting the scope of the claimed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a side view of an embodiment of a controllably releasable shifting tool. 
           [0012]      FIG. 2  is a side overview of a subsea oilfield with a riser and well assembly accommodating hardware with the shifting tool of  FIG. 1  disposed therein. 
           [0013]      FIG. 3A  is a side sectional view of the tool engaged with a valve of the hardware of  FIG. 2 . 
           [0014]      FIG. 3B  is a side sectional view of the valve of  FIG. 3A  upon uphole disengagement and closure by removal of the tool. 
           [0015]      FIGS. 4A-4D  are sequential cross sectional views of an actuator mandrel of the valve and a deforming collet element of the tool upon alternate uphole emergency disengagement. 
           [0016]      FIG. 5A  is a front sectional view of an embodiment of the shifting tool and initial diameter prior to the emergency disengagement sequence of  FIGS. 4A-4D . 
           [0017]      FIG. 5B  is a front sectional view of the tool of  FIG. 5A  with a reduced diameter following the emergency disengagement sequence of  FIGS. 4A-4D . 
           [0018]      FIG. 6  is a perspective view of an alternate embodiment of a single collet element of the tool. 
           [0019]      FIG. 7  is a flow-chart summarizing an embodiment of utilizing a controllably releasable shifting tool in a downhole environment. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Embodiments are described with reference to certain downhole assemblies that make use of a valve and valve actuator. In particular, production assemblies that are configured for disposal across cased and open-hole regions at various well locations are detailed. More specifically, subsea completions employing formation isolation valves are depicted. However, embodiments of a controllably releasable shifting tool as detailed herein may be directed at a variety of different actuator types. For example, actuators for triggering different types of valves, sliding sleeves, packer setting tools and other substantially permanent downhole devices may be configured for engagement with a shifting tool as described herein-below. Similarly, the oilfield environment need not be subsea as depicted. Regardless, however, the shilling tool is particularly configured to allow for controlled or ‘emergency’ release in a predictable and reliable manner heretofore unseen. 
         [0021]    Referring now to  FIG. 1 , a side view of an embodiment of a controllably releasable shifting tool  100  is shown. The tool  100  includes collet elements  130  which are each outfitted with an engagement portion  175  configured to engage an actuator of a downhole tool, for example to shift a valve  360  closed as shown in  FIGS. 3A and 3B . Additionally, each element  130  is also configured to allow for controlled emergency release or disengagement in a predictable manner. So, for example, in certain circumstances the noted valve  360  may be stuck open such that even several thousand pounds of load pull imparted on the tool  100  is insufficient to initiate actuator function (e.g. 2.000 lbs.-5,000 lbs.). Therefore, rather than allow the tool  100  or actuator features to damage or break, a controlled disengagement may be achieved. That is, disengagement may be achieved in a substantially damage-free manner relative each element  130  as well as features of the actuator and valve  360  as detailed below. Thus, future operation of the valve  360  is unlikely to be compromised even upon failure of actuator shifting. 
         [0022]    Unlike conventional emergency release techniques, the above noted disengagement of the tool  100  is achieved in a manner of enhanced controllability. More specifically, each collet element  130  is equipped with a central deformable region  150 . This region  150  is of a thickness that is substantially below that of the noted engagement portion  175 . Similarly its thickness is substantially below that of a base portion  125  which is structurally secured to a delivery tool  110 , in this case wash pipe. Thus, the central deformable region  150  is located between portions  125 ,  175  of substantially greater resistance to deformation upon imparting of a load on the tool  100 . Ultimately, this may lead to a controlled deformation that provides a predictable release where appropriate. 
         [0023]    As to specific potential differences in thickness between the central region  150  and the adjacent base  125  and engagement  175  portions, a wide range of options may be utilized. For example, for most embodiments, the difference in thickness may be anywhere between about 25% to about 90%. More specifically, in one embodiment a difference of between about 40-70% is employed with the deformable region  150  being of between about 75 to 125 thousandths of an inch thick compared to adjacent portions  125 ,  175  of between about 145-185 thousandths of an inch thick. 
         [0024]    Of course, there is no particular requirement that the base  125  and engagement  175  portions be of identical thicknesses on a given collet element  130 . However, in certain embodiments, each portion  125 ,  175  of a given collet element  130  is of substantially similar thickness. Further, to ensure predictability in the noted deformation, each central deformable region  150  of each collet element  130  is substantially similar in thickness. Indeed, by the same token, each base portion  125  of all collet elements  130  is substantially similar in thickness as is each engagement portion  175  relative one another. Once more, while each engagement portion  175  is of a keyed or changing profile, a transition location  127  of the portion  175  is provided which displays a consistency of thickness. Thus, as a matter of measured comparison for a given collet element  130 , this location  127  of the engagement portion  175  is of substantially similar thickness to the base portion  125  in the preferred embodiment noted above. 
         [0025]    Continuing with reference to  FIG. 1 , the tool  100  is configured for deployment via a wash pipe delivery tool  110 . Such may be provided as part of a larger overall gravel packing or other assembly, depending on the nature and stage of downhole operations. To this end, the overall tool  100  depicted includes a central flow thru channel  185  terminating at a conventional bull nose region  180 . However, a variety of different tool configurations may be utilized, generally ranging between about 2-4 inches in diameter. In fact, due to the generally thinner nature of the above detailed central deformable region  150 , the diameter of the channel  185  may be at the larger end of the spectrum and the overall length of the tool  100  reduced as compared to conventional shifting tool. For example, in one embodiment, the channel  185  may be over about 3 inches and the length of the tool  100  below about 90 inches, thereby enhancing flow capacity and reducing overall tool weight and size for sake of transport. 
         [0026]    Referring now to  FIG. 2 , with added reference to  FIGS. 3A and 3B , a side overview of a subsea oilfield  200  is shown whereat a riser  225  and adjoining well  280  are located. As shown in  FIG. 2 , hardware  260 ,  265  of the well  280  is depicted with the shifting tool  100  of  FIG. 1  disposed therein. More specifically, the hardware includes a packer  260  for isolating a largely open-hole leg  285  running through a formation  290  along with a valve housing  265  for containing a formation isolation valve  360  as referenced above and detailed further below. Thus, fluid communication as between production tubing  250  within the riser  225  and the interior of the leg  285  may be regulated. 
         [0027]    Continuing with added reference to  FIGS. 3A and 3B , the valve  360  may be in an open position with the tool  100  disposed through the housing  265  and into the leg  285 . As such, applications directed at the leg  285  may proceed. So, for example, an application such as gravel packing may be directed through a control unit  277  and other surface equipment  275  disposed at a rig platform  279 . By the same token, however, at the completion of such applications in the leg  285 , the shifting tool  100  may be withdrawn back up through the housing  265  and tubing  250 . This may be done in a manner that simultaneously closes the valve  360  as described below. As such, other applications, such as the installation of additional hardware above the packer  260 , may proceed in a manner that is safely isolated from any production fluid influx from the leg. Similarly, the closed valve  360  may also prevent heavier uphole application fluids from undesirably leaking into the leg  285 . 
         [0028]    Continuing with reference to  FIG. 2 , with added reference to  FIG. 1 , the shifting tool  100  is with collet elements  130  that include a central deformable region  150  of comparatively reduced thickness. Thus, as indicated above, the size of the tool  100  as well as the footprint of associated delivery equipment may be similarly reduced. So, for example, easier transport to the rig floor  279  may result along with added space thereat, both of which may be particularly beneficial in the case of offshore operations as depicted. 
         [0029]    Referring now to  FIGS. 3A and 3B , side sectional views of the shifting tool  100  are shown disposed within the valve housing  265 . More specifically,  FIG. 3A  reveals the tool  100  engaged with an actuator mandrel  365  for the open formation isolation valve  360 .  FIG. 3B , on the other hand shows this ball valve  360  in a closed position in conjunction with the upward pull and disengagement of the tool  100  from the mandrel  365 . 
         [0030]    With specific reference to  FIG. 3A , the shifting tool  100  is shown upon initiation of its uphole removal through the valve housing  265  and production tubing  250 . Thus, the engagement portion  175  of the tool  100  engages with the actuator mandrel  365  of the formation isolation valve  360 . As such, continued upward pull results in an upward shift of the mandrel  365  thereby rotatably closing off the valve passage  375  relative the otherwise open interior  300  of the housing  265  (see  FIG. 3B ). Thus, the uphole interior  350  of the hardware is now fluidly isolated from the noted housing interior  300 . With added reference to  FIG. 2 , isolation of riser  225 , production  250  and other uphole tubular disposed hardware is now achieved relative the leg  285  below the packer  260  and housing  265 . Therefore, completions and other uphole applications may proceed in a fluidly isolated manner relative the leg  285  as detailed above. 
         [0031]    Additionally, in circumstances where the upward pull on the actuator mandrel  365  is compromised and stuck, the shifting tool  100  is outfitted with collet elements  130  that are configured to avoid pull induced tool breakage. That is, upon exceeding a load pull in excess of a predetermined amount, the tool  100  will ultimately disengage from the mandrel  365  regardless of whether or not a completed valve closure has been achieved. More specifically, in one embodiment, a load in excess of 50,000 lbs. will result in disengagement of the engagement portion  175  relative a recess  367  of the mandrel  365 , provided certain sequential movement occurs as detailed further below. Having such substantial loads available without undue concern over damage to the tool  100  and/or mandrel  365  also increases the likelihood that a stuck actuator may be dislodged and unstuck prior to disengagement and release. Further, the substantial load may be applied for longer time than previously possible. That is, the more time spent applying the load, the more time the force is transmitted and propagated through the system. Thus, the likelihood is increased of overcoming obstacles such as debris or corrosion that may impede valve functionality. 
         [0032]    With added reference to  FIGS. 4A-4D , this release may be achieved through the controlled deformation of the central region  150  of the collet element  130 . As such, a reduced diameter (D) of the tool  100  may be achieved so as to allow an emergency release thereof where appropriate (see also  FIGS. 5A and 5B ). As detailed hereinabove, this controlled deformation of the central region  150  may be a result of substantially thicker base  125 , transition  127  and/or engagement  175  portions of each element  130  immediately adjacent the noted region  150 . By the same token, however, the central region  150  may also be of sufficient thickness to achieve shifting of the mandrel  365  without any notable deformation in circumstances where no sticking thereof is involved (as depicted in  FIG. 3B ). 
         [0033]    With more specific reference now to  FIGS. 4A-4D , cross sectional views of the actuator mandrel  365  being pulled upward (arrow  480 ) by the engaged collet element  130 . More specifically, increasing sequential deforming of the central region  150  of the element  130  is apparent as the load pull progresses. That is, with the actuator mandrel  365  stuck in place and incapable of shifting upward (arrow  480 ), the pull imparted through the underlying support mandrel  140  is translated into a predictable deformation. Indeed, with added reference to  FIG. 1 , this deformation may be substantially uniformly displayed throughout each collet element  130  of the tool  100  such that a controlled or ‘emergency’ disengagement from the stuck mandrel  365  is achieved. 
         [0034]    Continuing with reference to  FIG. 4A , in one embodiment, a load of between about 10,000 lbs. and about 25,000 lbs. is sufficient to initiate the deformation of the central region  150  as noted at  401 . This deformation is responsive to the immobility of the actuator mandrel  365  as noted above. Further, the central region  150  is comparatively thinner than the adjacent portions  125 ,  175 . The engagement portion  175  in particular includes a thicker transition  127  as well as a profile for engagement with the recess  367  of the actuator mandrel  365 . 
         [0035]    With added reference to  FIGS. 4B-4D , the nature of the engagement between the matching profile of the engagement portion  175  and the recess  367  begins to change with continued upward pull (arrow  480 ). That is, an interface  475  at this location begins to take on an increasing angular orientation of the engagement portion  175  relative the recess  367 . Similarly, the continued pull results in ever increasing but predictable plastic deformation of the comparatively thinner central region  150  as noted at  402 ,  403  and  404 . 
         [0036]    In one embodiment, the initial deformation at  401  is achieved by application of loads upwards of 25,000 lbs. as noted above. The continued increase in load may result in additional discrete deformations  402 ,  403  of  FIGS. 4B and 4C  at loads of between about 40,000 lbs. and about 45,000 lbs. Further, continued increase in load pull to in excess of about 100,000 lbs. may result in the deformation  404  depicted in  FIG. 4D . However, such values are only exemplary and alternate collet element  130  embodiments may be tailored for different types and increments of deformation based on material choices, overall dimensions and other factors. Additionally, the imparting of such loads need not be on a sustained continuous basis. Rather, as described further below, cycles of load, perhaps of lower values, may be utilized in attaining the depicted deformation. 
         [0037]    Continuing with reference to  FIGS. 4A-4D  and with added reference to  FIG. 1 , the compressive accordion-like responsiveness of the noted deforming region  150  is repeated for each element  130  of the shifting tool  100 . Thus, from a radial perspective, the tool  100  may be set to take on a slightly reduced overall diameter (D′) relative its profiled engagement portions  175  (see  FIG. 5B ). By the same token, however, the engagement portions  175  may remain locked into engagement with the recess  367  and associated tooth-like features. Therefore, an initial larger overall diameter (D) may persist. 
         [0038]    With added reference to  FIGS. 5A and 5B , a reduction a diameter reduction for the tool  100  may be achieved following the controlled deformation as noted above. Namely, the work string, including the tool  100  and each support mandrel  140  and element  130  thereof may be shifted in a downhole direction (see arrow  490 ). This may be directed through conventional surface equipment  275  as depicted in  FIG. 2 . Thus, a release of the engagement portion  175  from the recess  367  may be achieved, at which time, the overall diameter of the tool  100  may naturally reduce (from D to D′). Once more, as described further below, this alternating of upward (arrow  480 ) and downward (arrow  490 ) motion may be employed without allowing for release but rather as an alternate technique for enhanced control over the deformation. 
         [0039]    Referring now to  FIG. 6 , a perspective view of another embodiment of collet element  630  is depicted. Similar to the element  130  of  FIG. 1 , the element  630  of  FIG. 6  is equipped with an engagement portion  675  for interfacing downhole features as described hereinabove. Further, the central region  650  may again be of a lesser thickness (T″) as compared to the thicknesses (T′″, T′) of the adjacent portion  625  and location  627 . However, in addition to such thickness variations, the element  630  may be configured with a host of other dimensional characteristics tailored for control over deformation as detailed above. 
         [0040]    Continuing with reference to  FIG. 6 , additional dimensional characteristic variations are apparent. For example, the element  630  may be of lesser width (w″) at the central region  650  as compared to widths (w′″, w′) at the adjacent portion  625  and location  627 . Similarly, the length (L″) may differ substantially from that of the adjacent portion  625  (see L′″) and location  627  (see L′). Further, with reference to a central axis  600  of the overall tool  100 , the radius (r′″, r″, r′) may vary relative different positions ( 625 ,  650 ,  627 ). More specifically, in the embodiment shown, the central region  650  is located at a position reflecting a radius (r″) that is between the radiuses (r′″, r′) of the portion  625  and the location  627 . In some embodiments, the particular radiuses (r′, r″, r′″), widths (w′, w″, w′″), lengths (L′, L″, L′″) and thicknesses (T′, T″, T′″) may all be a matter of tailored design choice, with specific values selected based on loads, material choices and other variables affecting the controlled deformation. 
         [0041]    Referring now to  FIG. 7 , a flow-chart summarizing an embodiment of utilizing a controllably releasable shifting tool in a downhole environment is depicted. As with embodiments described above, the shifting tool may be provided along with a delivery tool that is utilized in any of a variety of downhole applications (see  705 ). For example, the shifting tool may be utilized following gravel packing in a generally open-hole section of a well. Regardless, following the interventional application, the shifting tool may be brought into engagement with an actuator as indicated at  720 . For embodiments depicted above, the actuator is utilized in conjunction with a formation isolation valve. Although in other embodiments, different types of valves and other devices may be triggered by an actuator as described herein. 
         [0042]    Once in place, the shilling tool may be utilized for activating the actuator as indicated at  735 . So, in the example of the valve noted above, the valve may be closed by such activation. However, in circumstances where the activation fails due to a stuck actuator arm or mandrel, collet element regions of the shifting tool may be controllably deformed as noted at  765 . This is achieved through the use of comparatively thin central regions of each collet element. Thus, unpredictable collet breakage and/or unduly low load pull tolerances (e.g. below about 10,000 lbs.) may be avoided. In fact, even in circumstances where load pull is sought to remain below a given amount, say about 50,000 lbs., multiple cycles of load pull may be utilized as indicated at  780 . As such, the controlled deformation may be achieved without application of a continuous pull of substantially greater amounts. 
         [0043]    Regardless, with either the actuator shifted or the controlled collapse achieved, the shifting tool may be released from engagement as indicated at  750 . Thus, as noted at  795 , the delivery and shifting tools may be safely removed from the well. 
         [0044]    Embodiments described hereinabove include tools and techniques for allowing emergency release of a shifting tool in a controlled and reliable manner. Once more, the controlled release is reliable enough that release need not be set at a load of less than 10,000 lbs. In fact, application of load pull in excess of 50,000 to 100,000 lbs. or more may be safely utilized without undue concern over shifting tool breakage in a downhole location. As a result, stuck actuator arms may be more frequently dislodged or unstuck with the shifting tool already in place. Thus, downhole operations may proceed in a more streamlined fashion with less frequent need for separate interventions to address stuck actuator arms. 
         [0045]    The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. Regardless, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.