Patent Description:
The present disclosure generally relates to shear pin tools and methods, more particularly self-retaining shear pin tools and methods, for connecting downhole tubulars in a wellbore.

Drilling, operating, and maintaining wells includes placing downhole tubulars within wellbores. Shear pins (e.g., shear pins or shear screws with partially threaded shanks) can be employed to connect downhole tubulars in the wellbore. Shear pins can serve as a "weak-link" in the connected downhole tubulars. Application of an increased axial load that exceeds a predefined threshold on the shear pins causes the pins to fail and the downhole tubulars to separate and move freely.

<CIT> describes a self-flaring rivet and the method of making the same. The end remote from the rivet head carries the swaging mechanism that is pulled outwardly to flare the end, inherently applying a tension force. This swaging mechanism also can be designed to remain in the rivet end or be pulled out completely.

<CIT> describes a shear pin assembly to be used in a blind radial hole on a rotor assembly stack. The blind radial hole is located at the interface between the disks that form the rotor stack and has a slot cut into one of the disks. The shear pin is disposed in the blind radial hole and includes, a cylindrical body, a cavity, and a cam pivotally disposed in said cavity. When the shear pin is installed, the cam is pivoted into the slot, locking the pin in the blind radial hole.

<CIT> describes a plurality of tubular rivets received on a reusable mandrel having a head and a stem, each rivet having a recess in its tail end which can accommodate a ring of metal separated by the mandrel head from the internal wall of the rivet set in a previous rivet-setting operation.

<CIT> describes an aircraft fastener element, as a collar or nut. The collar or nut has a bearing surface which abuts against the adjacent surface of the workpiece aperture in an initial predetermined area so that when the collar is swaged or the nut tightened and compressed the initial annular base is flattened to no more than approximately <NUM> D, with D being the internal diameter of the nut or collar.

<CIT> describes a shear pin connection for use in a difficult to access location has a bolt head to be positioned at an inner end of a bearing. A bushing is received between the bolt and an inner periphery of the bearing. A lock member is positioned between an inner end of the bushing and the bolt head. The lock member is radially expandable, and has a free radially outer dimension that is smaller than an inner dimension of the inner bore. The lock member is expandable to have an expanded radially outer dimension that is greater than the inner dimension of the inner bore. A nut is tightened on the outer end of the bolt. The nut causes the bushing to move relative to the bolt, and causes the lock member to expand radially.

<CIT> describes a quick release pin has an elongated body having an axial bore therethrough, a shaft extending at least partially through the axial bore for axial movement along the bore; a spindle separately mounted on a first end of the shaft; a button separately mounted on a second opposite end of the shaft; and a handle having a central passage through which the button extends, wherein the handle is mounted to the elongated body.

This specification describes self-retaining shear pin tools and methods to connect downhole tubulars in a wellbore. During operation, under high axial loading, the separated parts of the shear pin tool are retained which prevents them from falling into downhole equipment causing equipment malfunction.

These tools and methods provide an approach which allows separation of downhole tubulars and retention of portions of the self-retaining shear pin tool after shearing takes place. The tools can include a cap and a shear pin. The shear pin can include a body, and one or two swage dies. The self-retaining shear pin tool can be installed into an aperture with a recess of a tubular and a force is applied to the tool. Upon application of the force, the swage die causes the body portion of the shear pin to expand and to change dimension. The dimensional change of the body locks the shear pin into the aperture of the tubular so it is no longer free to move.

In some aspects, a self-retaining shear pin tool for connecting downhole tubulars in a wellbore includes a cap having an inner side and an outer side opposite the inner side, the cap defining a first recess formed in the inner side of the cap, the first recess of the cap having a cylindrical portion and a frustoconical portion extending from the cylindrical portion towards the outer side of the cap; and a shear pin disposed partially in the first recess of the cap and extending out of the first recess of the cap. The shear pin includes a body; a first recess extending inward from a first end of the body, the first recess having a cylindrical portion and a frustoconical portion between the cylindrical portion and the first end of the body; a second recess extending inward from a second end of the body, the second recess having a cylindrical portion and a frustoconical portion between the cylindrical portion of the second recess and the second end of the body; a first swage die disposed in the first recess of the body; and a second swage die disposed in the second recess of the body.

A self-retaining shear pin tool is defined in claim <NUM>.

Embodiments of the self-retaining shear pin tool for connecting downhole tubulars in a wellbore can include one or more of the following features.

In some embodiments, the body of the shear pin is a thread-less body.

In some embodiments, the body of the shear pin defines a channel extending between the first recess and the second recess of the shear pin.

In some embodiments, the first recess has diameter between <NUM> and <NUM>.

In some embodiments, the swage die includes a length between <NUM> and <NUM>, and an outer diameter between <NUM> and <NUM>.

In some embodiments, the body of the shear pin is a cylindrical body.

In some embodiments, the shear pin and the cap are attached by a press-fit.

In some embodiments, the shear pin includes materials with coefficients of thermal expansion that can achieve a self-tightening assembly when heated.

In some embodiments, the swage die has a transition or an interface fit with the body of the shear pin.

In some embodiments, the cap of the shear pin defines a second recess formed on the outer side of the cap. In some cases, the second recess comprises a hex recess.

In some cases, the shear pin is disposed partially in the first recess of the cap and extending out of the first recess of the cap.

In some embodiments, the body of the shear pin defines a channel extending from the recess of the body to the end of the shear pin.

A method for connecting downhole tubulars in a wellbore is defined in claim <NUM>.

Embodiments of the method for connecting downhole tubulars in a wellbore can include one or more of the following features.

In some embodiments, the method includes preventing pressure changes from exerting forces on the self-retaining shear pin tool by using a channel formed in the shear pin.

In some embodiments, the method includes forcing a swage die into a body of the shear pin and loading the shear pin to failure. In some cases, the method includes disconnecting the first tubular and the second tubular by applying an axial load that exceeds the mechanical capacity of the body of the shear pin. In some cases, the method includes forcing a swage die into a threadless body of the shear pin.

The retained portions of the shear pin cannot exit the aperture of the downhole tubular and fall or move freely within the wellbore. This limits challenges during operation such as debris entering downhole equipment that can cause equipment malfunction. The self-retaining shear pin reduces or eliminates the need for encapsulation of the tool or addition of retention mechanism to prevent parts of the shear pin tool from falling out of the component during operation.

Some other approaches retaining the parts of the shear pin tool include adding threads to a portion of the shear pin shank, installing a retention feature behind the shear pin (e.g., threaded cap, circlip, dowel pin, peened edge), gluing a portion of the shear pin in place, and an interface or press-fit to a portion of the shear pin. However, these approaches add design complexity, additional operation steps, and increased cost of parts inventory and assembly. In contrast, the described self-retaining shear pin tool includes a threadless body that reduces design complexity and the requirement for the components to match during manufacturing. The threadless body design can eliminate the need for high precision manufacturing of multiple parts where all threads need to accurately engage. The self-retaining shear pin tool can be installed in a single operation and all parts are retained. It does not require access for side pins or extra parts to be installed. The dimensional change is repeatable and can give a designer confidence that the mechanical properties (e.g., pull-out force, depth, or volume of engagement) are consistent.

The details of one or more embodiments of these systems and methods are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of these systems and methods will be apparent from the description and drawings, and from the claims.

This specification describes self-retaining shear pin tools and methods to connect downhole tubulars in a wellbore. During operation, under high axial loading, the separated parts of the shear pin tool are retained which prevents them from falling into a downhole equipment causing equipment malfunction. These tools and methods provide an approach which allows separation of downhole tubulars and retention of the portions of the self-retaining shear pin tool after shearing takes place. The tools can include a cap and a shear pin. The shear pin can include a body, and one or two swage dies. The self-retaining shear pin tool can be installed into an aperture with a recess of a tubular and a force is applied to the tool. Upon application of the force, the swage die causes the body portion of the shear pin to expand and to change dimension. The dimensional change of the body locks the shear pin into the aperture of the tubular so it is no longer free to move.

<FIG> is a schematic view of a wellsite <NUM> that includes a self-retaining shear pin tool <NUM> installed connecting two downhole tubulars 106a and 106b. As illustrated, the wellsite <NUM> includes a derrick <NUM> that supports downhole tubulars 106a and 106b within a wellbore <NUM>. The self-retaining shear pin tool <NUM> is configured as a single homogeneous component to connect the downhole tubulars 106a and 106b within the wellbore <NUM>. A single self-retaining shear pin tool <NUM> is shown for clarity, but multiple self-retaining shear pin tools may be installed. In this example, the self-retaining shear pin tool <NUM> includes two or more separate components. The design of the self-retaining shear pin tool <NUM> helps retain components of the tool upon axial loading to separate the tubulars and to prevent equipment malfunction during operation.

<FIG> is a cross-section of the self-retaining shear pin tool <NUM>. The tool <NUM> includes a cap <NUM> and a shear pin <NUM>. In some implementations, the cap <NUM> has an outer diameter between <NUM> and <NUM>, an inner diameter between <NUM> and <NUM>, and a thickness between <NUM> and <NUM>. In some implementations, the shear pin <NUM> has a cross-section between <NUM> and <NUM> based on the available space, shear load requirements, and the material. The length of the shear pin <NUM> is based on the radial space available within the tool or assembly. The cap <NUM> has an inner side <NUM> and an outer side <NUM> opposite of the inner side <NUM>. The cap <NUM> defines a first recess <NUM> defined by the inner side <NUM> of the cap <NUM>. The recess <NUM> of the cap <NUM> has a cylindrical portion <NUM> and a frustoconical portion <NUM> extending from the cylindrical portion <NUM> towards the outer side <NUM> of the cap <NUM>. The frustoconical portion <NUM> extends into the cross-sectional area of the tool <NUM> defined transverse to the axis of the first recess <NUM>. In this example, the cap <NUM> includes a second recess <NUM> (e.g., a hex recess, a slot, or a keyway) for a tool (e.g., Allen key) to be used during installation.

The shear pin <NUM> is disposed partially in the first recess <NUM> and extends out of the first recess <NUM> of the cap <NUM>. In this implementation, the shear pin <NUM> includes a body <NUM> that is threadless and two swage dies 137a, 137b. The body <NUM> is cylindrical. The body <NUM> defines a first recess 138a with a cylindrical portion and a frustoconical portion between the cylindrical portion of the first recess 138a and a first end 139a of the shear pin <NUM>. The body <NUM> also defines a second recess 138b with a cylindrical portion and a frustoconical portion between the cylindrical portion of the second recess 138b and a second end 139b of the shear pin <NUM>.

The body <NUM> also defines a channel <NUM> extending between the first recess 138a and the second recess 138b of the shear pin <NUM>. The presence of the channel <NUM> can prevent pressure changes from exerting forces on the tool <NUM> that can act upon the swage dies 137a, 137b. In this example, the channel <NUM> is a single axial thru-hole or a bypass method that can equalize the pressure between the cavity within the body <NUM> and the environment. The channel can include a radial hole, multiple holes, grooves, or combinations thereof. The first swage die 137a is disposed in the first recess 138a of the body <NUM>. The second swage die 137b is disposed in the second recess 138b of the body <NUM>. In other examples, the shear pin <NUM> can include only one swage die at one end of the body <NUM>. For example, in some embodiments, the cap <NUM> and the shear pin <NUM> are a single unitary component. The swage dies 137a, 137b have profiles that engage with the body <NUM>. The swage dies 137a, 137b can include the same or different material than the cap <NUM> and the body <NUM> of the shear pin <NUM>. The materials can include materials with coefficients of thermal expansion properties that will enable tightening of the shear pin <NUM> in hot environments. For example, brass has a thermal expansion coefficient between <NUM> and <NUM> × <NUM>-<NUM> m/m °C and carbon steel has a thermal expansion coefficient between <NUM> and <NUM> ×<NUM>-<NUM> m/m °C. The higher thermal expansion coefficient in brass allows clearances to tighten together when inserted. In some implementations, the swage die <NUM> can include a transition or interference fit with the body <NUM> such that the swage die <NUM> is retained when initially assembled. This allows a fully assembled tool to be stored as a single unit within a workshop or a storage environment. This design can retain the swage die during routine handling and storage while allowing the swage die to move during operation. In other shear pin tools, a light strength adhesive (e.g., loctite) is used to achieve the same design.

During installation of the shear pin tool <NUM>, the swage dies 137a, 137b are pressed into the first recess 138a and the second recess 138b of the body <NUM> of the shear pin <NUM>, respectively. The swage dies 137a, 137b cause the body <NUM> to expand, change shape, exceed the yield point of the material, and permanently deform.

The geometry and the material of the shear pin <NUM> can enable a designer to adjust the failure threshold of the tool <NUM>. For example, a body with an increased cross-section or a material that includes a high yield property can increase the load capacity that the shear pin tool <NUM> can withstand. This allows the shear pin tool assembly to withstand an increased loading before the separation of the tubulars takes place. In some implementations, the cap <NUM> and the shear pin <NUM> can include the same material. In this example, the cap <NUM> and the shear pin <NUM> include different material. For example, a shear pin <NUM> of the tool <NUM> can include soft materials (e.g., brass) and be press fitted or bonded with the cap <NUM>. In some implementations, the body <NUM> can be designed to not shear (e.g., serve as a self-locking fastener). For example, to fit parts together without external thru-holes. This type of fastener could be used to fit car or aircraft panels which are forcibly pressed together and are aesthetically pleasing once installed. The fasteners, which are installed in blind holes then swage out, permanently attaching the panels or parts together. From the front there would be no visible fasteners. This can also be advantageous for vandal resistant or tamper resistant applications (e.g., once the parts are pressed together there is no externally exposed fastener). Similarly this could be used on enclosures and devices assembled on production lines since the parts can be easily pressed together to give a smooth exterior appearance without screw holes. Once fitted could only be opened again by destructive means.

<FIG> illustrate the installation and the use of the self-retaining shear pin tool <NUM>. The self-retaining shear pin tool <NUM> is used to attach a first tubular 106a and a second tubular 106b together. In <FIG>, the installation includes placing the self-retaining shear pin tool <NUM> through an aperture <NUM> into the tubular 106a with a recess <NUM> formed in the second tubular 106b. The tubulars 106a, 106b are positioned with the aperture <NUM> in the tubular 106a aligned with the recess <NUM> in the tubular 106b.

As illustrated, the recess <NUM> of the downhole tubular 106b has a dovetail shape. The internal dovetail shape can be machined with a standard tooling. In some implementations, the aperture can include a circumferential groove, a discrete pocket, a tee slot, a trapezoidal slot, an oval slot, and a recess profile into which the self-retaining shear pin tool <NUM> can dimensionally change. In <FIG>, an axial load is applied on the self-retaining shear pin tool <NUM> and the tool <NUM> is pressed in the first tubular 106a and the second tubular 106b. The tool <NUM> is in direct contact with the end of the recess <NUM>. As illustrated, the cap <NUM> is not fully inserted yet and has space for more insertion (i.e., before contact between the cap <NUM> and the shoulder of the aperture <NUM>). The swage dies 137a, 137b are in contact with the aperture <NUM> and the cap <NUM> but not pushed fully into the body <NUM> of the shear pin <NUM>. In <FIG>, continuous load application on the tool <NUM> drives the swage dies137a, 137b into the body <NUM> of the shear pin <NUM>. This causes the axial load to exceed the yield load of the body <NUM> and the body <NUM> to change dimensionally. Dimensional changes of the body <NUM> provide the expanded ends. These ends lock the tool <NUM> into place so that it is unable to be withdrawn or fall out from the recess <NUM>.

The dimensional changes of the shear pin <NUM> can also provide an interference fit between the cap <NUM> and the sides of the aperture <NUM> in the tubular 106a. The interference fit prevents the cap <NUM> from slackening or loosening. This allows the tool <NUM> to be resistant to forces that can loosen the cap <NUM> (e.g., torque, vibration, or tension) without relying on additional retention methods (e.g., threadlock, wire, pinned, or peening). In some implementations, the cap <NUM> can be partially loose as the expanded ends prevent the cap <NUM> from being fully removed while the shear pin <NUM> is not under loading. This provides ease of tool installation and reduces the cost of additional retention methods. The user installing the tool <NUM> can note the tight connection once the tool <NUM> is fully inserted into the aperture <NUM>. It can be observed that the body <NUM>, where shear takes place, is spaced apart from the swage dies 137a, 137b. The body <NUM> in shear can mimic a traditional shear pin. In some examples, the body shape can differ from the ends where the swage dies 137a, 137b act. This allows shape flexibility of the tool for a designer.

In <FIG>, the axial load is applied to the self-retaining shear pin tool <NUM> exceeding the threshold value of the tool and the tool <NUM> fails. This allows the downhole tubulars 106a, 106b to disconnect and slide apart. Separation of the tool <NUM> takes place when the stress through the body <NUM> of the shear pin <NUM> exceeds the mechanical capacity of the body136. The cap <NUM> and part of the shear pin <NUM> are retained in the aperture <NUM> of the outer tubular 106a and part of the shear pin <NUM> is retained in the inner tubular 106b because the body <NUM> is dimensionally changed. The swage dies 137a, 137b are trapped in place and also retained. This prevents equipment malfunction during operation as the tool cannot fall in the downhole equipment.

The self-retaining shear pin tool can be assembled or operated in a variety of ways without departing from this disclosure. For example, the self-retaining shear pin tool can include blanking caps installed in place of the shear pin of the tool. This reuse of components reduces parts inventory and allows the number of pins installed in each tool to be adjusted based on the demand. In another example, the tool can include a threaded cap. The cap can be installed and retained by other installation approach. For example, an installation approach that can generate a clamping force on the pin and initiate dimensional changes in the body. The cap can be a press fit or interference fit and driven into place by a force. The act of driving the cap by force can force the swage dies into the body and the dimensional change of the body to lock the self-retaining tool in place. In another example, the cap and the shear pin can be installed in a separate operation during an assembly process.

The parts of the tool can be formed in variety of shapes that allow dimensional changes. For example, the body and the swage die can include serrations, raised bands, or combinations thereof. The geometry can prevent the swage die from being withdrawn once driven into place and the body from loosening. The imposed dimensional changes of the body can cause the body to mechanically lock into the serrations or similar features. This mechanical interference can provide more resistance to motion than friction. In another example, the outside surface of the body can be smooth, notched, include serrations, or bands to prevent the body from being withdrawn or moving within the aperture. In another example, the body can include pre-cut slots or geometric features to preferentially cause advantageous dimensional changes (e.g., longitudinal slots). In other example, the tool design can be planar and used as a flat snap connector. In some implementations, the aperture of the downhole tubulars can include circumferential bands, recess, cone, ribs, pocket, local dimple, conical protrusions, or geometric features that cause dimensional changes in the body.

<FIG> is a cross-section of a downhole tubular with a raised vee design aperture <NUM> on each side 248a, 248b. For installation, the self-retaining shear pin tool <NUM> can be forced into the raised vee apertures 248a, 248b and position the shear pin <NUM> at an angle to engage with the aperture. The tool <NUM> and the aperture <NUM> can include variety of designs that enable mechanical deformation of the shear pin <NUM> of the tool <NUM>. For example, if the recess or groove includes geometry to flare or otherwise expand the shear pin, the pin itself will not require the swage die since the geometry will expand the shear pin end. This makes the shear pin potentially less complex and economical to manufacture with fewer parts.

<FIG> is a model grid showing deformation <NUM> of the self-retaining shear pin tool <NUM> under axial load. A design of the self-retaining shear pin tool <NUM> was modelled using finite element simulation software (CDESP Quick Connect) to analyze tool deformation under loading. Initial contours of stress distribution along the simulated design of the tool <NUM> confirm that the body <NUM> of the tool <NUM> can be mechanically deformed under load. The load is imposed by the swage dies 137a, 137b.

The described tool can also be used in mass-manufacturing of parts that are permanently attached (e.g., car panels, aerospace assembly, or construction platforms). The described tool provides the rigid attachment without a use of traditional screw fasteners. Rather, the parts can be pressed together and achieve a permanent attachment. The tool can be applicable in assemblies where a fastener is positioned behind an inaccessible object. This type of fastener can be used where an object needs to be attached but the entry to the rear of the object is not accessible. The object can be pressed into place from the accessible side and the self-retaining shear pin tool will stay retained. The design is scalable and can be used for applications in small and large equipment. For example, it can be used in MEMS and micro devices. All components of the assembly are in direct contact and can be electrically conductive to provide mechanical connections in electrical equipment. For example, the tool can allow large diameter high current bus bar connections that are press fit for application in power generation, offshore and wind turbines, industrial machinery, and power distribution. The tool can be used as a mechanical puller if threads are added to the design. The design can be used as a removal tool and the previously connected components can be redressed and reused. It would also allow the sheared portion of the tool to be forcibly withdrawn from the cap and the cap to be refurbished and/or reused.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular implementations. Certain features that are described in this specification in the context of separate implementations can be implemented, in combination, in a single implementation. Conversely, various features that are described in the context of a single implementation can be implemented in multiple implementations, separately, or in any suitable sub-combination. Moreover, although previously described features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can, in some cases, be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

Claim 1:
A self-retaining shear pin tool (<NUM>) comprising:
a cap (<NUM>) having an inner side (<NUM>) and an outer side (<NUM>) opposite the inner side (<NUM>), wherein the cap defines a cap recess (<NUM>) formed in and defined by the inner side (<NUM>) of the cap, the cap recess (<NUM>) having a cylindrical portion (<NUM>) and a frustoconical portion (<NUM>) extending from the cylindrical portion towards the outer side (<NUM>) of the cap (<NUM>); and
a shear pin (<NUM>) configured to be disposed partially in the cap recess (<NUM>) and to extend from the inner side of the cap (<NUM>) out of the cap recess (<NUM>), the shear pin comprising:
a body (<NUM>) defining a body recess (<NUM>) with a cylindrical portion and a frustoconical portion between the cylindrical portion and an end (<NUM>) of the shear pin; and
a swage die (<NUM>) configured to be disposed in the body recess and cause the body (<NUM>) of the shear pin (<NUM>) to expand.