Release Tool

This application is a continuation of U.S. non-provisional patent application Ser. No. 18/229,091 filed Aug. 1, 2023, entitled “Release Tool”, which claims benefit of U.S. provisional patent application No. 63/394,137 filed Aug. 1, 2022, entitled “Release Tool”, both of which are hereby incorporated herein by reference in their entirety for all purposes.

Not applicable.

Subterranean wellbores are drilled into hydrocarbon bearing, earthen formations in the interest of producing hydrocarbons from the wellbore. During completion operations for subterranean wellbores, it is conventional practice to install a tubular casing string or simply “casing” in the wellbore and then perforate the casing string with perforating guns located within a central passage of the casing string to provide many paths for formation fluids (e.g., hydrocarbons) to flow into a central passage of the casing string. The perforating guns are typically positioned along a toolstring that is conveyed into the wellbore via a wireline or other suitable workstring. The toolstring deployed into the wellbore may include, along with the perforating guns, various other components and equipment to assist with positioning the toolstring at a desired location within the casing string, and for sealing or plugging the casing string at the desired location. Following plugging and perforating of the casing string, the toolstring, including the fired perforating guns, are typically retrieved to the surface.

In some instances, the toolstring may become stuck deep within the wellbore before the toolstring has been retrieved to the surface, making the expensive and risky endeavor of creating a hydrocarbon producing wellbore significantly more expensive as completion of the wellbore is delayed for potentially weeks as operators attempt to retrieve the stuck toolstring. One circumstance where toolstrings may become stuck in a wellbore is in response to the violent detonation of the perforating guns of the toolstring. Particularly, the violence of the detonation may damage the perforating guns, making the guns vulnerable to becoming hung in a casing joint or other irregularity in the casing string.

As described above, while such perforating operations are often performed at the end of a wireline which is able to pull on stuck tools with considerable tension, it is not entirely uncommon for tools to become stuck deep within the wellbore such that the tension applicable by the wireline is insufficient for releasing the stuck toolstring. In such a scenario, the approach is typically to disconnect an uphole portion of the toolstring from the stuck tool and retrieve the uphole portion of the toolstring from the casing string leaving the stuck tool therein. Subsequently, it may be arranged for a fishing rig to visit the well site for either grabbing the stuck tools and wrestling them out of the wellbore (with substantially greater pulling force than that provided by the wireline) or for breaking the tools up within the wellbore such that the remains may be flushed from the casing string.

A particularly problematic scenario occurs when, in an attempt to extract the toolstring from the casing string, tension applied to the wireline results in the wireline failing or snapping such that an extended run of the wireline lies loosely on the stuck tool occupying hundreds of feet of the wellbore. To eliminate the risk of a snapped wireline, it is typical practice to include a ballistic release tool in the toolstring at an uphole end thereof that is appended to the end of the wireline. The ballistic release tool may be remotely triggered by an operator at the surface to disconnect the wireline from the toolstring. Although ballistic release tools are typically not activated on a given run into a wellbore, the insurance provided by the ballistic release tool is relied on and utilized by the operators of the toolstring as the toolstring is deployed through the wellbore, permitting the operators to complete the perforating operation as quickly as possible. Unfortunately, failures of ballistic release tools are not unknown either.

Particularly, there are generally three basic failures for ballistic release tools. First, the ballistic release tool must reliably carry electric signals and power from the wireline to the toolstring extending downhole from the release tool. Second, the ballistic release tool must not release unless it is given the appropriate signal from the surface. Third, the ballistic release tool must release the toolstring from the wireline when the appropriate signal is received by the release tool. All three failure types are typically driven by both (1) the substantial and recurring bending forces endured by the toolstring at the surface as the toolstring is hoisted from the ground up into the air above the wellbore prior to being inserted into the wellbore, and (2) the substantial and recurring tension endured by the toolstring when the toolstring is pulled uphole through the casing string after most or all of the perforating guns of the toolstring have been fired and physical contact between the remains of the fired perforating guns and the casing string results in the application of considerable frictional drag on the wireline.

What is needed and desired by the industry is a more robust and more reliable release tool that may be reused over and over with confidence.

This disclosure more particularly relates to release tools for securing downhole tools to a workstring and optionally releasing the downhole tool in a wellbore extending through a subterranean earthen formation where the release tool includes a downhole housing and an uphole assembly. The downhole housing has an uphole end and a downhole end opposite the uphole end for connecting to the downhole tool. The uphole assembly includes an uphole housing with an uphole end and a downhole end. The uphole end of the uphole assembly couples to the workstring and the downhole end of the uphole assembly couples to the downhole housing. In some embodiments, the release tool includes a lock ring to secure the uphole housing to the downhole housing when in a locked state where the lock ring is pressed outwardly towards a locking groove prevented from deflecting inwardly. The lock ring additionally includes an unlocked state in which the lock ring is allowed to deflect inwardly away from the locking groove such that the uphole housing is permitted by the lock ring to disconnect from the downhole housing. Additionally, in some embodiments, the release tool includes a movable wedge having a first position to prevent the lock ring from deflecting inwardly and a second position that permits the lock ring to deflect inwardly. The movable wedge is movable from the first position to the second position while downhole. Further, in certain embodiments, the release tool includes a combustion element to propel the movable wedge from the first position to the second position thereby enabling the disconnect and release of the downhole housing from the uphole housing in response the uphole assembly receiving a release signal, such as a release signal communicated from the surface.

This disclosure also relates to a release tool for securing a downhole tool to a a workstring within a wellbore and optionally releasing the downhole tool in that wellbore. In some embodiments, the release tool includes an uphole housing and a downhole housing connected to the uphole housing when the release tool is in a locked-in state and disconnected from the uphole housing when the release tool is in an a separate unlocked state. In some embodiments, the release tool includes a moveable wedge attached to both the uphole housing and the downhole housing, and a lock ring disposed in the downhole housing. The lock ring has a locked state in which the lock ring is restricted from compression toward a reduced radius by the moveable wedge to lock the downhole housing to the uphole housing, and an unlocked state in which the lock ring may be compressed toward a reduced radius enabling the downhole housing to be released from the uphole housing. In certain embodiments, the release tool includes an actuation module configured to move the moveable wedge relative to the lock ring to permit a radius reduction of the lock ring thereby shifting the lock ring from the locked state to the unlocked state in response to receiving a release signal, such as a release signal communicated from the surface.

In another aspect of this disclosure, a release tool is provided for securing a downhole tool to a workstring system such as a wireline system within a wellbore and optionally releasing the downhole tool within the wellbore. In some embodiments, the release tool comprises an uphole housing and a downhole housing attached end-to-end by a lock ring (e.g., a c-ring) nested into an inner locking groove formed on the inside of one of or both of the uphole housing and the downhole housing. In certain embodiments, the release tool includes a load shoulder arranged to press against a lower end of the c-ring in response to the application of a tensile load on the uphole and downhole housings. In certain embodiments, the release tool includes a wedging device having a locked state that prevents the c-ring from lifting out of the inner locking groove and an unlocked state that permits the c-ring to rise out of the locking groove. In certain embodiments, the release tool includes a combustion element configured to transition the wedging device from the locked state to an unlocked state.

And in a further aspect, this disclosure relates to a release tool for securing a downhole tool to a workstring system such as a wireline system into a wellbore and optionally releasing the downhole tool in that wellbore where the release tool comprises an uphole housing and a downhole housing connected end-to-end with a low explosive combustion element configured to selectably disconnect the uphole and downhole housings from one another.

In an embodiment, a release tool is disclosed for releasably securing a workstring to a downhole tool deployable into a wellbore extending through a subterranean earthen formation. The release tool includes a downhole housing having a downhole end for connecting to the downhole tool and an uphole end opposite the downhole end, and an uphole assembly. The uphole assembly includes an uphole housing having an uphole end connectable to the workstring and a downhole end connectable to the downhole housing, and a lock ring configured to releasably secure the uphole housing to the downhole housing, wherein the lock ring has a locked state in which the lock ring is pressed outwardly towards a locking groove of the downhole housing whereby the lock ring is prevented from deflecting radially inwards, and an unlocked state in which the lock ring is allowed to deflect radially inwards away from the locking groove whereby the uphole housing may disconnect from the downhole housing. The uphole assembly additionally includes a movable wedge moveable between a first position preventing the lock ring from transitioning from the locked state to the unlocked state and a second position permitting the lock ring to transition from the locked state to the unlocked state, and a combustion element configured to propel the movable wedge from the first position to the second position to release the downhole housing from the uphole housing in response the release tool receiving a release signal.

In an embodiment, a release tool is disclosed for releasably securing a workstring to a downhole tool deployable into a wellbore extending through a subterranean earthen formation. The release tool includes an uphole housing connectable to the workstring, a downhole housing connected to the uphole housing when the release tool is in a locked state and disconnected from the uphole housing when the release tool is in a released state, and a moveable wedge coupled to the uphole housing and positioned in the downhole housing. The release tool additionally includes a lock ring disposed in the downhole housing and having a locked state in which the lock ring is restricted from radially contracting by the moveable wedge to lock the downhole housing to the uphole housing, and an unlocked state in which the lock ring is permitted to radially contract thereby permitting the downhole housing to be released from the uphole housing, and an actuation module configured to move, in response to receiving a release signal, the moveable wedge relative to the lock ring to transition the lock ring from the locked state to the unlocked state.

In an embodiment, a release tool is disclosed for releasably securing a workstring to a downhole tool deployable into a wellbore extending through a subterranean earthen formation. The release tool includes a downhole housing having an uphole end, and a downhole end connectable to the downhole tool, and an uphole assembly including an uphole housing having an uphole end connectable to the workstring and a downhole end connectable to the downhole housing, and a lock ring secured to the uphole housing and disposed within the downhole housing when the release tool is in a locked state, wherein the lock ring has a locked state in which the lock ring locks the uphole housing to the downhole housing, and an unlocked state in which the lock ring is unlocked from at least one of the uphole housing and the downhole housing such that the downhole housing is permitted to move relative to the uphole housing along a central axis of the release tool. In addition, the uphole assembly includes a piston having a first position that maintains the lock ring in the locked state and a second position that permits the lock ring to transition from the locked state to the unlocked state, and a combustion element configured to shift, in response to the uphole assembly receiving a release signal, the piston from the first position to the second position and thereby transition the release tool from the locked state to a released state in which the downhole housing is released from the uphole housing.

In an embodiment, a release tool is disclosed for releasably securing a workstring to a downhole tool deployable into a wellbore extending through a subterranean earthen formation. The release tool includes an uphole housing and a downhole housing, wherein the uphole housing is connected to the downhole housing in a locked state of the release tool, and the uphole housing is released from the downhole housing in a released state of the release tool, an inner locking groove formed on a radially inner surface of one of the uphole housing and the downhole housing with a lock ring nested into the inner locking groove, and a load shoulder configured to press against a downhole end of the lock ring in response to the application of tension against the uphole housing and the downhole housing. In addition, the release tool includes a wedge that, in a locked state, prevents the lock ring from escaping the inner locking groove and, in an unlocked state, permits the lock ring to escape from the locking groove, and a combustion element configured to transition the wedge from the locked state to the unlocked state.

In an embodiment, a release tool is disclosed for releasably securing a workstring to a downhole tool deployable into a wellbore extending through a subterranean earthen formation. The release tool includes an uphole housing and a downhole housing, wherein the uphole housing is connected to the downhole housing in a locked state of the release tool, and the uphole housing is released from the downhole housing in a released state of the release tool, and a low explosive combustion element configured to transition the release tool from the locked state to the released state in response to the release tool receiving a release signal.

In an embodiment, a release tool is disclosed for releasably securing a workstring to a downhole tool deployable into a wellbore extending through a subterranean earthen formation. The release tool includes a downhole housing having a downhole end for connecting to the downhole tool and an uphole end opposite the downhole end, and an uphole assembly including an uphole housing having an uphole end connectable to the workstring and a downhole end connectable to the downhole housing, and a lock ring configured to releasably secure the uphole housing to the downhole housing, wherein the lock ring has a locked state in which the lock ring is pressed outwardly towards a locking groove of the downhole housing whereby the lock ring is prevented from deflecting radially inwards, and an unlocked state in which the lock ring is allowed to deflect radially inwards away from the locking groove whereby the uphole housing may disconnect from the downhole housing. In addition, the uphole assembly includes a movable wedge moveable between a first position preventing the lock ring from transitioning from the locked state to the unlocked state and a second position permitting the lock ring to transition from the locked state to the unlocked state, and at least one push off lug axially translatable from a recessed position to an extended position, wherein an uphole face of the at least one push off lug faces a downhole face of the moveable wedge and a downhole face of the at least one push off lug faces the downhole housing such that the at least one push-off lug translates from the recessed position to the extended position as the moveable wedge translates from the first position to the second position whereby an axially directed downhole force is applied to the downhole housing by the downhole face of the at least one push off lug in the extended position. Further, the release tool includes a combustion element configured to propel the movable wedge from the first position to the second position to release the downhole housing from the uphole housing in response the release tool receiving a release signal.

The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment. Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis. Any reference to up or down in the description and the claims is made for purposes of clarity, with “up”, “upper”, “upwardly”, “uphole”, or “upstream” meaning toward the surface of the borehole and with “down”, “lower”, “downwardly”, “downhole”, or “downstream” meaning toward the terminal end of the borehole, regardless of the borehole orientation. Further, the term “fluid,” as used herein, is intended to encompass both fluids and gasses.

Referring initially to, a workstring or wireline systemis shown for deploying a toolstringinto a cased wellborefor performing a perforating operation such as, for example, a plug and perforating (“plug-and-perf”) operation. While embodiments of release tools described herein may typically be used in conjunction with wireline systems (e.g., wireline system) as part of a plug-and-perf operation, it may be understood that release tools described herein may be quite useful with most any type of downhole workstring system including, for example, coiled tubing, a threaded tubular string comprising a plurality of tubular joints connected end-to-end, a threaded rod string, and other conceivable systems useful for conducting work downhole within a wellbore and with whatever downhole tools may be used for the establishment of a hydrocarbon producing wellbore or maintenance or repair of the same.

As described above, wellborecomprises a cased wellbore in which casing (commonly called a casing string) is installed. Cased wellboreextends from the surface far into the Earth and into an extended generally horizontal run within a hydrocarbon bearing formationdeep in the ground. It may be understood that prior to inserting toolstringinto cased wellbore, a crane (not shown in) positioned adjacent the cased wellboremay be utilized for vertically lifting the toolstringabove a surface assembly(only partially shown inand including, e.g., a wellhead, a valve tree) whereby toolstringmay be vertically lowered and run through the surface assemblysuch that toolstringmay be inserted into the cased wellbore.

The toolstringof wireline systemincludes a number of tools that are selected by an operator of the cased wellborefor facilitating the performance of the plug-and-perf operation. In this exemplary embodiment, toolstringincludes, among other components, a plugat a downhole end thereof, one or more perforating gunspositioned uphole from the plug, and a release toollocated at an uphole end thereof. It may be understood that toolstringmay include additional components such as, for example, tools for providing pressure isolation and/or electrical communication across the toolstring, as well as a setting tool for setting the plugwithin the cased wellbore(e.g., actuating the plugfrom a run-in configuration to a set configuration in which the plugsealingly anchors to the cased wellbore).

As will be described further herein, release toolof toolstringattaches to a workstring or wireline. Particularly, the wirelineextends from a wireline truck of the surface assembly, and is typically quite long to permit the toolstringto run potentially miles down into and through the cased wellbore. It may be generally understood that wellbores, including cased wellbore, extend vertically downwards from the surface along a vertical section thereof and then curve towards a generally horizontal path or section that is typically a great length (e.g., a mile or more) horizontally through a hydrocarbon bearing zone (e.g., formationshown in).

As shown in, toolstringis lowered and typically pumped downhole through the cased wellboreto a generally horizontal section thereof where the wellboreextends a significant distance along within a hydrocarbon bearing formation. At a desired location in the cased wellbore, the plugof toolstringis set or deployed to both seal and anchor against the inside of the casing (not shown in) to isolate an uphole portion of the cased wellbore(the portion of cased wellboreextending uphole from the set plug) from a downhole portion (the portion of cased wellboreextending downhole from the set plug) of cased wellbore. The plug, once set, prevents fluid that will be pumped downhole from surface assemblyintended to frack newly created perforations in the cased wellborefrom escaping downhole past the set plugand into previously formed perforations and preventing the needed build in fluid pressure to frack the newly created perforations. It may be understood that significant hydraulic pressure is required to enlarge and extend new perforations so plug-and-perf operations typically begin bt plugging off the downhole existing perforations (e.g., previously fracked perforations), separating the set plugfrom the remainder of the toolstringso that new perforations may be created in the cased wellboreuphole from the set plug. Once the plugis disconnected from toolstring, the toolstringmay lay on a vertical bottom (relative to the direction of gravity) of the horizontal section of the cased wellbore. With the toolstringlocated on the vertical bottom of the cased wellbore, toolstringmay be pulled uphole toward the surface while each of a number of perforating gunsof toolstringare detonated at predetermined positions to shoot or discharge shaped explosive charges puncturing the cased wellbore(e.g., perforations formed in the casing of the cased wellbore) thereby creating a new perforation therein.

As described above, in some instances the toolstringmay become stuck in the cased wellborebefore being retrieved to the surface. For example, the remains of the fired perforating guns, still attached to the toolstring, may catch against or hang onto a casing joint positioned along the cased wellbore. As just one example, a piece of shrapnel of one of the fired perforating gunsmay catch into a groove formed in a casing joint of the casing of the cased wellbore, causing the remains of the fired perforating gunto become stuck against the casing joint thereby preventing further uphole travel of the now stuck toolstring. While it is generally preferable to retrieve toolstringintact from the cased wellbore, in at least some instances, it may be necessary to activate the release toolto separate the toolstringfrom the wireline, permitting the wirelineto be conveniently and quickly retrieved to the surface without the stuck toolstring. Later, at least a portion of the stuck toolstringmay be drilled out or otherwise broken up into flow-transportable debris that may be washed or flushed from the cased wellbore(e.g., returned to the surface assembly). In this manner, operators of wireline systemmay avoid the undesirable need of calling in a fishing rig in an attempt to fish the stuck toolstring(along with the severed portion of the wireline) from the cased wellbore, an unpredictable process which may take days or weeks before the stuck toolstringmay be successfully retrieved from the cased wellbore. The extended downtime caused by the stuck toolstringmay substantially increase the overall costs associated with placing the cased wellboreinto production.

Turning now to, an embodiment of the release toolis shown. As described above, the release toolmay be used in wireline-deployed toolstrings such as a plug and perf toolstrings (e.g., the toolstringshown in) that are run downhole deep into a wellbore (e.g., cased wellboreshown in) where the possibility exists of the toolstring becoming stuck (e.g., irretrievable via a wireline connected therewith) in the wellbore. In this exemplary embodiment, release toolgenerally includes a first or uphole housingcoupled end-to-end to a second or downhole housing. As will be described further herein, release toolhas a locked state in which the uphole housingis connected to the downhole housingand a released state in which the downhole housingis disconnected from the uphole housingsuch that the uphole housingmay be separated from the downhole housing(e.g., retrieved to the surface leaving the downhole housingwithin the wellbore).

In addition to housingsand, release toolincludes a top subcoupled (e.g., screwed into) to the uphole end of the uphole housing. The uphole end of top subis configured for connecting to a wireline (e.g. wirelineshown in) or other deployment tool. Further, release toolincludes a bottom subcoupled (e.g., screwed into) to the downhole end of the downhole housingfor connecting to the bulk of the toolstring, especially the portion of the toolstring including the perforating guns (e.g., perforating gunsshown in) which are subject to substantial damage and deformation in response to their firing within the wellbore. If the toolstring becomes irretrievably (e.g., via the wireline or other deployment tool) stuck in the wellbore, the release toolmay be activated to separate the uphole housingfrom the downhole housing(e.g., transition release toolfrom the locked state to the released state) where the downhole housingmay be left with the bulk of the toolstring in the wellbore.

In this exemplary embodiment, many of the internal components and operating elements of the release toolreside within and stay with (e.g., are not separated from) the uphole housingfollowing the transition of release toolto the released state. In this way, the bulk of release toolmay be successfully retrieved to the surface by the wireline (or other deployment tool) along with the uphole housinginstead of remaining in the wellbore with the remainder of the toolstring. As such, the uphole housingcomprises a component of an integrated uphole assembly indicated by arrowin.

In the present disclosure, embodiments of release tools disclosed herein, including the release tool, are powered by an energetic element that may generally be characterized as a low explosive producing high pressure combustion gasses configured to drive and move a locking mechanism of the release toolfrom a locked state to an unlocked state. In comparison, prior art ballistic release tools typically detonate high explosive energetics to explosively break apart one or more components of a locking mechanism of the conventional release tool. The detonation of a high explosive produces particularly destructive power generally characterized by a shock wave driven by the high velocity propagation of a detonation front of the explosion exceeding the speed of sound. In such conventional ballistic release tools, the destructive power of a high explosive is intended to break apart ballistically some critical connective structure of the conventional release tool to transition ballistically the conventional release tool to a released state. In comparison, embodiments of release tools disclosed herein, including release tool, are designed not for ballistic destruction via a shockwave, but for disconnection via fluidic pressure. Particularly, embodiments of release tools disclosed herein utilize high pressure gas as a medium to drive the locking mechanism which, since it is not sacrificial as with the locking mechanisms of conventional ballistic release tools (which are intentionally destroyed by the detonation of a high explosive) and may thus be designed robustly such that at least an uphole assembly thereof (e.g., uphole assembly) may be reused for a considerable number of deployments into multiple wellbores.

Providing an overview of the operating elements of release tool, and as shown particularly in, a top or uphole end of the uphole housingaccommodates an actuation moduleof release toolthat is located just below the top sub. Coupled or screwed into the uphole housingbelow the actuation moduleis a mandrelof the release toolwhich extends in a downhole direction from the uphole housingand into the downhole housing. In this exemplary embodiment, mandrelincludes an axially extending passage with an electric communication barof the release tooldisposed centrally therein for carrying electrical power and/or signals between the wireline connected to the uphole end of release tooland the toolstring coupled to the downhole end of release tool.

In this exemplary embodiment, a bottom collar or catch sleeveof release toolis coupled or screwed onto a radially outer surface of mandrelat a downhole end thereof, thereby substantially filling the inner diameter of the downhole housing. Additionally, a tubular pistonof release toolis configured to be carried on the radially outer surface of the mandreland which is configured to seal against the radially outer surface of the mandrelalong with the a radially inner surface (e.g., defining the inner diameter of uphole housing) of the uphole housing. However, the tubular pistonis also free to slide or translate axially (albeit with considerable frictional resistance) with respect to both the uphole housingand mandrel. Securing the upper assemblyto the downhole housingis a locking mechanism or ringof release toolhaving peripheral (radially outer) circumferential ridges or dogs(indicated in) configured to press or settle into a corresponding circumferential inner locking grooveformed along a radially inner surface (e.g., defining an inner diameter of the downhole housing) of the downhole housing(two grooves are shown, but a profile including a single groove or multiple grooves are within the scope of the present disclosure) when the lock ringis in a locked state. Once received in the inner locking grooveof downhole housing, the circumferential ridgesof lock ringare held within the inner locking grooveby a wedging action of a moveable wedgeof the release toolpositioned along the periphery or radially outer surface of tubular piston.

As shown particularly in, in this exemplary embodiment, the mandrelis coupled or screwed into the uphole housingat a location where uphole housinghas a relatively greater radial wall thickness. Similarly, in this exemplary embodiment, the mandrelis coupled or screwed into a bulky section of the catch sleevehaving an enlarged radial thickness. The shape of catch sleeveaccommodates the tubular pistonwhereby the pistonis permitted to move axially downhole a considerable length thereof while also having a ring or load shoulderat an uphole end thereof positioned a similar distance back uphole toward the uphole housingand located proximal the downhole end of the lock ring. In this exemplary embodiment, the load shoulderof catch sleevehas a blunt configuration to press against the lock ringto dislodge the same from the circumferential inner locking grooveof the downhole housingas release tooltransitions from the locked state to the released state. In this manner, catch sleevemay carry the lock ringback to the surface following the separation of release tool.

As shown particularly in, to explain how the lock ringis supported for locking the mandrelto the downhole housing, it should be understood that the volume of the downhole housingwithin the lock ringis substantially occupied by the mandrel, electric communication barand tubular pistonas shown in. In this configuration (corresponding to the locked state of release tool), there is no available space for the lock ringto deform and slip from the circumferential inner locking groove.

In comparison,shows the tubular pistondisplaced further (to the right in) into the downhole housingwhereby a circumferential relief grooveformed on the periphery of the tubular pistonis positioned radially between inner dimension of the lock ringand the mandrelcreating an annular void space (the movable wedgebeing axially offset from lock ringin this arrangement) for the lock ringto flex into or settle in as the load shoulderof catch sleevepresses the lock ringuphole and out of the downhole housing. In this exemplary embodiment, frangible shear members or screwsandof release tool(which hold toolin the locked state until it is desired to transition toolto the released state) are shown having been sheared in the process of the tubular pistonmoving axially downhole into the downhole housing. The circumferential inner locking groovemay have a sloped or inclined surface in the upward or uphole direction that serves, along with an appropriate ridge profile on the outer periphery of the lock ring, as a ramp-like profile to press the lock ringinto a compressed form (shown in) as it is pressed out of the inner locking groove. And although the lock ringis shown to have a reduced diameter, it may be preferred in some instances for the lock ringto have a resting or unstressed configuration (shown in) such that the ridge profile tends to press outwardly and fully into the inner locking groovefor ease of assembly and for reducing friction against the tubular piston.

Referring to, details of the lock ringare shown. It may be noted that in this exemplary embodiment, lock ringincludes the circumferential ridgesformed along a radially inner surface or diameter of lock ringand which are designed to lock into the two corresponding circumferential inner locking grooveswith an inclined slope that enables the lock ringto slide out of the circumferential inner locking groovewhen under an axial load imposed by the load shoulder. The lock ringis also shown into have a “C” shape in this exemplary embodiment (e.g., lock ringcomprises a C-ring in this exemplary embodiment). Particularly, in, lock ringis shown is in an expanded state with a notable gap between the opposed ends of the “C”. Lock ringis shown in a contracted state inin which lock ringis released from the circumferential inner locking groove. It may be observed that an outer diameter of the lock ringis greater when in the expanded state than when in the contracted state such that opposed arcuate ends of lock ringare positioned closer together when the lock ringis in the contracted state, the state lock ringtakes when being pressed out of the circumferential inner locking groovein the outer housing. Additionally, in this exemplary embodiment, stress cutsare arranged along the radially inner surface of lock ringto lead lock ringto maintain a more circular shape as it expands and contracts in diameter. In at least some applications, it is desired that the lock ringnot develop stress concentrations along its circumference making it deform in a less of a uniformly circular configuration and bend more in a “V” shaped configuration.

Turning now to, it is noted that the release toolis generally configured to be deployed many times into one or more subterranean wellbores before ever needing to be activated (e.g., transitioned from the locked state to the released state) t in order to leave a stuck toolstring (e.g., toolstring) in a wellbore. Thus, the mechanical components of the release toolare generally engineered to withstand a great number of deployment cycles in which tension is applied to the release tool(e.g., from wireline) resulting from mangled perforating guns being dragged uphole through the cased wellbore. However, the electrical and combustible elements of release toolare generally not as reliable as the mechanical components and thus may not be as trustworthy over a similarly great number of deployment cycles. As such, the electrical and combustible elements of release toolmay, in some applications, be routinely inspected, redressed, and/or replaced. To make this convenient and simple for such inspection and redressing, access to the electrical and combustible components of release toolis provided to an operator of the release toolat the top or uphole end of the release tooljust under the top sub. It is likely that such inspections and any redressing may be done in the field by personnel that may only open a respective release toola few times per year rather than in a manufacturing setting where such personnel would open many such devices as part of their daily routine. So, in comparison, release toolis generally configured such that access to the electrical and combustible components thereof is generally more convenient compared to accessing and disassembling the mechanical (e.g., the locking and releasing components such as, for example, lock ring) components of the release tool.

Referring collectively to, the electrical and combustible components of release toolare carried in an actuation moduleof the release toolin this exemplary embodiment that is sized and fitted to be disposed within the open, uphole end of the uphole housingin one orientation, primarily due to an orienting pinprojecting off-axis from the downhole end of the actuation module. When properly oriented, the orienting pinslips into a corresponding alignment pocketformed in the uphole housing. Unless the orienting pinis received down into the alignment pocket, the actuation modulewill not settle fully into its position for the top subto be screwed to the uphole housing.

Actuation moduleis generally configured to actuate the release toolfrom the locked state to the released state in response to the actuation modulereceiving a predefined release signal, such as a release signal communicated from the surface assembly(e.g., via a signal generator of the surface assembly) via wireline. Particularly, actuation moduleis configured to displace axially the movable wedgeof the pistonin response to receiving the release signal whereby the lock ringof release toolis permitted to deflect or compress itself from the locked state (in which lock ringis secured to the downhole housing) to the unlocked state in which the uphole housingmay be pulled axially by the wirelinefrom the stuck downhole housingand separated from the toolstring.

In, a switch compartmentof actuation moduleis shown for receiving an electronic switch(e.g., a digitally addressable electronic switch) which is electrically connected to an electric contact pin(shown in). In this exemplary embodiment, the circuit formed from electronic switchand contact pinis completed by a radially oriented ground springof the actuation module. Switchmay be a digital switch including one or more processors, memory devices, and input/output (I/O) devices. Alternatively, switchmay be an analog electronic switch. Switchis connected to equipment at the surface (e.g., a surface controller of surface assembly) through a circuit including wirelineand is further connected to an energetic or combustion elementof the actuation modulein a manner that initiates combustion of a combustible portion of combustion elementand thereby begins the process of separating the uphole and downhole housingsandvia the fluid pressure generated by the ignited combustion element. Particularly, combustion elementis configured to generate sufficient fluid pressure (e.g., from pressurized gas emitted by combustion elementfollowing ignition) to transition release toolfrom the locked state to the without needing to ballistically break apart the lock ring(e.g., via the propagation of a shockwave).

In this exemplary embodiment, switchis insulated within the switch compartmentfrom the heat present in the downhole environment to reduce thermal degradation of the switchnoting that it is expected for the switchto be exposed to a number of thermal cycles over many deployment cycles of release toolin one or more separate wellbores. Referring to, switchis insulated by a pocket, pouch, cozy or other arrangement. Specifically, in the embodiment shown in, the switchis slipped into a pouchprior to installation in the actuation module. In an alternative embodiment shown in, a shaped insulation pouchof actuation moduleincludes a pocket for the switch to be inserted. The exemplary insulation pouchesandshown in, respectively, are made of a thermally insulating material and may comprise a multi-layer insulating material which may be rigid but preferably pliable to better fit into the compartmentfor the cover to set down securely for insertion of the moduleinto the top end of the uphole housing.

Referring again to, in this exemplary embodiment, combustion element, as generally described above, comprises a low or low-order explosive (LE) (e.g., black powder and/or other materials) configured, in response to ignition resulting from the actuation modulereceiving an appropriate release signal, to produce combustion gasses which acts as a propellant for applying an axially directed pressure force against the piston. Generally, the LE comprising combustion elementis not configured to produce a shockwave in response to ignition. In contrast, a high-order explosive (HE) often used in conventional release tools is characterized as producing a shockwave in response to detonation which would likely damage, destroy, or otherwise jeopardize the physical integrity and reliability of the upper housingin which the actuation moduleis positioned. However, the release toolrelies on the fluid (e.g., gaseous) pressure generated by the ignition of combustion elementto drive or propel, in a controlled manner (e.g., without destroying the internal components of release tool), the axial displacement of the pistonthrough the downhole housingto initiate the release of the downhole housingfrom the upper assembly. In other embodiments, combustion elementmay comprise other types of materials configured to selectably generate fluid pressure without also generating a shockwave which may jeopardize the physical integrity of upper assembly. For example, in other embodiments, combustion elementmay comprise pressurized gas contained within a sealed chamber that is selectably released to apply an axially directed pressure force against the piston. Additionally, in some embodiments, combustion elementcomprises a unitized ignitor and power cartridge.

It should be understood that an initiator may be useful as part of a combustion process or low explosive akin to a propellant to create a fluidic (e.g., gaseous) actuating force as compared to destruction explosive force associated with a detonator or with detonation associated with a high explosive. In this exemplary embodiment, the combustion elementis in a combustion compartmentof actuation moduleopposite from the switch compartmentand aligned to vent combustion gasses along a module flowpath (indicated by arrowin) formed in the actuation module. The combustion gasses produced by combustion element, once vented from the actuation modulealong module flowpath, continue travelling through a housing flowpathin fluid communication with module flowpathand which extends through the uphole housing.

In this exemplary embodiment, the combustion element, the module flowpathand the housing flowpathare aligned with the uphole end of the tubular pistonsuch that flowpathsandcollectively form a combustion flowpathfor conveying combustion gasses created by initiating of the combustion elementto flow to drive the tubular pistondownwardly. In other words, combustion gasses are permitted to travel along housing flowpath, thereby encountering the uphole end of tubular pistonwhereby the combustion gasses may apply a downhole axially directed pressure force against the uphole end of tubular piston. Referring to, tubular pistonis shown as having moved axially downhole (to the right in) in response to the application of the pressure force thereto, revealing an expansion chamberformed in uphole housingwhich increases in volume as the tubular pistonstrokes axially downhole. As described above, axial movement downhole of the tubular pistonrelieves the lock ringso that the circumferential ridgesof lock ringmay travel radially inwards from the circumferential inner locking grooveplacing lock ringthereby unlocking the lock ringfrom the downhole housing. It should be noted that at least a portion of the expansion chamberis part of the housing flow path.

Once fully stroked, one or more ventsof uphole housingallow the combustion gasses to escape from the release tooland into the surrounding environment (e.g., a subterranean wellbore environment) so as to depressurize the release tool, avoiding the hazard of an operator opening the toolin a pressurized state (which may release pressure unexpectedly) at the surface following deployment of the toolinto a wellbore. Also, as a precaution to unintentional stroking of the tubular piston, shear screwsand(shown in) are used to prevent relative axial movement of the piston(when in an unsheared state) until sufficient and considerable axial force is imposed by the combustion gasses through the module flowpathto the top of the tubular piston.

Referring again to, in this exemplary embodiment, the mandrelof release toolincludes a primary shear slotshown on a top side of the mandreland in which the shear screwis received, and a secondary shear slotcircumferentially spaced from primary shear slotand in which the shear screwis received. Shear screwmay be referred to herein as primary shear screwwhile shear screwmay be referred to herein as secondary shear screw. The principle difference between the primary shear slotand the secondary shear slotin this exemplary embodiment is that the primary shear slothas a shorter axial length (extending radially within the release tool) than the secondary shear slotwhere, in this exemplary embodiment, the difference in axial length between slotsandis greater than the thickness of the primary shear screw. By this arrangement, the primary shear screwmay absorb forces applied to the release toolprior to an activation of the toolfrom the locked state to the released state. For example, primary shear screwmay absorb vibratory forces incurred, for example, during shipping of the release tool, during multiple deployment cycles into one or more wellbores with various prior toolstrings, etc. However, in other embodiments, the relative axial lengths of shear screwsandmay vary from that disclosed herein. In still other embodiments, release toolmay include only one shear screw (e.g., primary shear screw).

By absorbing these forces prior to the activation of release tool, primary shear screw, which may be damaged to some degree by the forces applied thereto, protects the secondary shear screwfrom damage (e.g., accruing from the forces that are instead applied to primary shear screw) thereby preserving its full rated strength. As such, the combustion gasses produced by combustion elementdrives the tubular pistondownhole shearing off the primary shear screwwith its end extending into the primary shear slotwhether the primary shear screwis fully intact or compromised by age and vibration in response to the intentional activation of release toolto separate and thereby release the downhole housingfrom the upper assembly.

Additionally, as the tubular pistonprogresses slightly further downhole following the shearing of primary shear screw(before the wide circumferential relief grooveon the periphery of the tubular pistonenters radially inside the lock ring), the secondary shear screwmust first be sheared by the mandrel(placing the shear screwinto a sheared state) before the tubular pistoncan fully stroke as shown particularly in(with shear screwsandeach sheared into their respective sheared states). It may be understood that when the combustion elementis ignited, there is more than sufficient energy to shear off both of the shear screwsand, and the shear screws are only installed to prevent inadvertent stroking of the tubular pistondue to other causes that may not fully stroke and enable a full and certain transition of the release toolinto the released state. As shown particularly in, the shear screwsandmay be used in pairs (e.g., a pair of primary shear screwsand a pair of secondary shear screws) where the primary shear screwand primary shear slotare circumferentially spaced approximately 180 degrees opposite one another and the secondary shear screwand secondary shear slotare circumferentially spaced approximately 90 degrees from each of the primary shear screwsand primary shear slots, but approximately 180 degrees from one another.

After the shear screwsandare sheared and the tubular pistonfully strokes bringing the wide circumferential relief grooveinto an axially overlapping alignment with the lock ring(releasing the wedging structure that had prevented the circumferential ridgeson the periphery of the lock ringfrom releasing from the circumferential inner locking grooveon the inside of the downhole housing), a relief area is provided for the lock ring to recess into as the lock ringsqueezes itself out of the circumferential inner locking groove. The tension on the upper assemblyimposed from the wireline (not shown) forces the load shoulderaxially against the lower, blunt end of the lock ring, thereby pressing the lock ringinto the contracted state as shown inand freeing the upper assemblyfrom the downhole housing.

Referring to,particularly shows the upper assemblyin its complete form now free of the downhole housing. Additionally, it may be noted thatshows the lock ringassuming a preferred shape (e.g., the contracted state) while the lock ringremains captured by the load shoulderand lifted to the surface assembly.illustrates the downhole housingwhich is connected to the remainder of the toolstring through bottom sub. The open tubular shape of the uphole end of the downhole housingis a familiar shape for fishing systems that are deployed to well sites to recover tools and equipment that are stuck downhole.