Patent ID: 12247458

DETAILED DESCRIPTION

It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention.

A reference to U.S. application Ser. No. 17/275,509 filed Mar. 11, 2021, titled “Methods and Apparatus for providing a plug with a two-step expansion” can provide a detailed description of theFIGS.2to5. A quick background reference is done in this US application, as several embodiments are the same compared to the new US application as CIP with the improvement further described inFIGS.6to25.

FIG.2represents a cut view of an unset plug or run-in-hole plug, inside the tubing string1, along a tool axis12.FIG.2represents the unactuated or undeformed position for the plug and a retrievable setting tool, which allows traveling inside the tubing string1.

The plug may include the following components:an expandable continuous seal ring170,an expandable gripping ring161, which preferably includes anchoring devices74,a back-pushing ring160, including shear devices65which may be positioned on the inner diameter of the back-pushing ring160,a locking ring410, which includes a conical external shape matching the inner surface of the expandable gripping ring161and the inner surface of the expandable continuous seal ring170. The locking ring410may include a hemispherical inner surface419and a conical inner surface416, and,a hemispherical cup411.

The retrievable setting tool may include the following components:an external mandrel414, which may include a cylindrical pocket418. The pocket418may have a channel415linking the pocket418with the well fluid2present inside the tubing string1. In this representation, the external mandrel414may contact the locking ring410along the conical surface416. In addition, the external mandrel414may contact the hemispherical cup411along a conical surface417,a rod412which can move longitudinally within the external mandrel414. The rod412may provide a link to the shear devices65, securing the longitudinal position of the back-pushing ring160.

In addition, an untethered object413may be included inside the pocket418of the external mandrel414.

This embodiment may be referred to as ‘ball in place’, where the untethered object413may be a ball which is included in the retrievable setting tool. Other embodiments for the untethered object413may be a pill, a dart, a plunger, preferably at least a hemispherical or conical shape. Alternatively, the untethered objects413and313can be pumped or launched from surface inside the tubing string.

FIG.3represents a sequential step ofFIG.2. InFIG.3, the retrievable setting tool has been actuated, which induces the longitudinal movement indicated by arrow430of the rod412relative to the external mandrel414.

Through the connection of the shear devices65with the rod412, the movement of the rod412, indicated by arrow430, may induce the same longitudinal movement as the back-pushing ring160. The back-pushing ring may induce in turn an expansion movement to the expandable gripping ring161, which in turn induces an expansion movement through the deformation of the continuous expandable seal ring170. The expansion of the expandable gripping ring161and of the continuous expandable seal ring170occurs both longitudinally and radially over the conical external shape of the locking ring410. The locking ring is held longitudinally in position thanks to the contact416with the external mandrel414, as well as radially in position through the conical contact with the hemispherical cup411, itself held in position through the conical contact417with the external mandrel. To be noted during this expansion process, the hemispherical surface419of the locking ring410may not come in contact with the hemispherical surface421of the hemispherical cup411, keeping a longitudinal gap.

The expansion process of the expandable gripping ring may end when one of the anchoring devices74start penetrating inside the inner surface of the tubing string1, and a force equilibrium is established between the anchoring force or friction force created by the anchoring devices74with the shear devices65.

At this point, the expandable continuous seal ring170might not be in contact with the inner surface of the tubing string1. This can be due to possible stop of the expansion process of the expandable continuous seal ring170before reaching the inner surface contact with the tubing string1, and possible elastic restraint effect of the different parts after the setting process as described inFIG.3.

As depicted inFIG.3, the untethered object413may still remain inside the cylindrical pocket418of the external mandrel414.

The hemispherical cup411may stay in its longitudinal position thanks to the friction contact along its conical surface420in common with the inner conical surface of the locking ring410, or thanks to a clipping mechanism with the locking ring410.

FIG.4depicts a close-up view of a plug assembly, in a set position, with the caged untethered object landed on the hemispherical cup and pressing on the plug assembly using well fluid pressure.

As depicted inFIG.4, the untethered object413has landed on the hemispherical cup411and may contact the chamfer424.

A well fluid2may be pumped from uphole of the set plug, creating a flow restriction and in turn a local pressure uphole of the set plug and a force470on the uphole exposed plug components. The force470may act mainly on the untethered object413and the hemispherical cup411.

As depicted inFIG.4, the force470may induce a further longitudinal movement of the hemispherical cup411and the untethered object413. The longitudinal movement of the hemispherical cup may in turn create a radial deformation of the locking ring410through its inner conical surface420, which in turn may create a further radial deformation of the expandable continuous seal ring170.

The further longitudinal movement may continue up to surface contact of the hemispherical surface421of the hemispherical cup411together with the corresponding surface419on the locking ring410.

The force470is acting on the untethered object413and on the hemispherical cup411, with the two parts being in contact through a chamfer424and providing a force indicated by arrow480at this contact surface. The resultant force indicated by arrow481of these two parts may be directed perpendicular to the conical contact surface420with the locking ring410.

The expandable gripping ring161secured with the anchoring devices74inside the tubing string1and locked internally by the locking ring410, may not deform during the further expansion process of the expandable continuous ring170, and provide a radial sliding guide.

Having the hemispherical cup411in contact with the locking ring410, the resultant of the force470on the untethered object413and on the hemispherical cup411, may now directed towards forces483and484. Force483may compress the expandable continuous seal ring170further towards the tubing string, possibly enhancing the sealing feature of the plug. Force484may compress the expandable gripping ring161further towards the tubing string via the anchoring devices74, possibly enhancing the anchoring feature of the plug.

FIG.5represents a technique sequence100, which includes major steps depicted inFIG.2toFIG.4.

Step101corresponds to the deployment of a plug assembly (170,410,411,161,160) including a carried untethered object (413) into the tubing string (1) containing well fluid (2). During step102, the plug assembly with its expandable continuous seal ring (170) is deformed radially, and the expandable gripping ring (161) is expanded radially, both due to the action of a retrievable setting tool, over a locking ring (410) and hemispherical cup (411). During the same step102, the expandable gripping ring contacts at least one point of the inner surface of the tubing string (1), while the expandable continuous seal ring (170) is deformed to an outer diameter which may be less than the tubing string (1) inner diameter. Then, during step103, the retrievable setting tool, is retrieved. Further during step104, the carried untethered object (413), is released from the setting tool. Then, during step105, the untethered object (413) contacts radially the inner surface of the hemispherical cup (411). Then, during step106, the well fluid (2) pressure and flow restriction up-hole of the untethered object (413) and hemispherical cup (411) is used to act as a force to deform further the expandable continuous seal ring (170), up to its outer surface contact with the tubing string (1) inner surface, allowing further enhanced contact between all plug components from the untethered object (413) to the tubing string (1) passing through the hemispherical cup (411), the locking ring (410) and the expandable continuous seal ring (170). The same force may also enhance the anchoring action on the expandable gripping ring (161). This isolation state allows performing a downhole operation inside the well.

Thus, the disclosure describes a method comprising the step of providing a plug assembly. The plug assembly may include an expandable assembly, and a locking ring. The expandable assembly may comprise a continuous sealing portion and a gripping portion. The locking ring may include a flared outer surface and a stopping inner surface. The flared outer surface of the locking ring may be contacting the flared inner surface of the expandable assembly. The plug assembly may further include an inner surface. The method comprises the step of providing a cup. The cup may include an outer surface that is coupled to the inner surface of the plug assembly. The outer surface of the cup may be adapted to couple with the stopping inner surface of the locking ring. The method comprises the step of deploying the plug assembly and the cup into a tubing string containing well fluid. The method comprises the step of expanding the expandable assembly over the flared outer surface of the locking ring, whereby the expandable assembly may deform radially, for example, until the gripping portion of the expandable assembly contacts at least one point of an internal surface of the tubing string. Radially deforming the expandable assembly may occur through plastic deformation of metallic alloy. The method comprises the step of launching or releasing, such as from surface or from a setting tool, an untethered object inside the well fluid of the tubing string. The untethered object may include an outer surface adapted to couple with the cup. The method comprises the step of contacting the untethered object with the cup, after the expandable assembly is deformed radially. The method comprises the step of applying pressure on the untethered object using the well fluid whereby forces are applied to the cup. The force may cause one or more of a radial deformation of the continuous sealing portion of the expandable assembly, a contact of an internal surface of the tubing string with the continuous sealing portion of the expandable assembly, or a longitudinal movement of the cup while contacting the flared inner surface of the plug assembly, for example, until the cup contacts the stopping inner surface of the locking ring. The method comprises the step of penetrating the internal surface of the tubing string at the at least one point with the gripping portion of the expandable assembly.

In some embodiments, the method may comprise the step of diverting a portion of the well fluid outside the tubing string, or the step of sealing a portion of the well fluid inside the tubing string with the plug assembly. The method may comprise the step of dissolving at least one component of the plug assembly, the cup, or the untethered object.

FIGS.6to25depict an embodiment for a ball-in-place plug with an internal continuous expansion mechanism, including a cup and studs.

FIG.6represents a cross-section view of a ball-in-place plug in an unset position within a tubing string1and filled with well fluid2. The plug may comprise the following components:an expandable continuous sealing ring170an expandable gripping ring161, which may include one or more anchoring devices, represented as buttons74a locking ring310a hemispherical cup311a back-pushing ring160one or more studs312one or more load shearing device, represented as shear screws65one carried untethered object, represented as a ball313

The descriptions made in U.S. application Ser. No. 17/275,509 filed Mar. 11, 2021 for the continuous expandable seal ring170, the expandable gripping ring161, the anchoring devices74, the back-pushing ring160, can be taken as reference for this current CIP application.

All the plug components,170,161,74,160,310,311,312,65, including the untethered object313may be built out of dissolvable material. The dissolvable material may be a composite material or metallic alloy which may dissolve or decompose within the well fluid2. The dissolving or decomposition may include an oxidation-reduction or corrosion reaction with some components of the well fluid2.

The locking ring310, the hemispherical cup311, the studs312will be further detailed inFIGS.18to24.

The plug with the above listed components may typically be conveyed on a setting adapter. The setting adapter may include two components, namely an external mandrel322and an internal rod321. Both the external mandrel and internal rod may be part of the toolstring10, as globally depicted in the backgroundFIG.1. The toolstring10may be conveyed via a wireline cable, a coiled-tubing or flexible tubing, tractoring, or pumped down independently from surface inside the well fluid2. The toolstring10may include other measuring or actuating components, such as positioning or formation measurement devices, like CCL for Casing Collar Locator, GR for Gamma Ray, or any environment measurement such as pressure, temperature, resistivity, sonic, ultrasonic and any combination of the above. Typically, the toolstring10may also include perforating guns to create perforating channels, leading to fracturing channels7, as depicted inFIG.1. The toolstring10may also include an actuation tool which provide an actuation force, typically a longitudinal force, along axis12, with the purpose to displace longitudinally the external mandrel322relative to the internal rod321, or reversed. The actuation tool, not shown inFIG.6, may therefore be connected to the external mandrel322and to the internal rod321. The actuation tool may provide its longitudinal actuation force through different means, such as power charge, hydrostatic downhole pressure, electric motor, embedded explosive or any combination. The goal of the actuation tool may be to actuate or set the plug, such as the one depicted inFIG.6, by longitudinally displacing the external mandrel322relative to the internal rod321, after receiving a command to start the displacement. The command to start the displacement of the actuation tool may come from a wired signal to an addressable switch, a programmed signal internally inside the toolstring10based on a position or specific environment within the tubing string1, a wireless signal sent from another device within the tubing string1, a nearby tubing string or surface device communicating with the toolstring10.

FIG.7represents a sequential step following the step described inFIG.6.FIG.7depicts the same embodiment asFIG.6for a ball-in-place plug with an internal continuous expansion mechanism, with the plug in a set position. The actuation tool may have initiated a longitudinal movement between the internal rod321relative to the external mandrel322. This longitudinal movement associated with a pulling or pushing force is symbolized with arrow340. Note that the longitudinal movement or displacement is relative to two groups of parts and could be equally symbolized with an opposite movement of the external mandrel322relative to the internal rod321.

FIG.7represents a cross-sectional view of the plug at the end of the setting movement. The longitudinal displacement of the internal rod321relative to the external mandrel322may include a relative displacement in the range of 0.5 in to 12 in [12.7 mm to 305 mm]. Together with the internal rod321movement, the back-pushing ring160linked with pre-loaded shearing devices65may induce the same longitudinal displacement. Note that the pre-loaded shearing devices65are represented as shear screws, though other shearing devices such as ring or studs may be included between the internal rod321and the back-pushing ring160.

The longitudinal movement of the locking ring160may induce a longitudinal movement of the expandable gripping ring161relative to the locking ring310. Due to the flared external surface of the locking ring310and the corresponding flared inner surface of the expandable gripping ring161, the longitudinal movement of the expandable gripping ring161may include an induced radial expanding movement of the expandable gripping ring161.

The continuous expandable seal ring170may have a longitudinal contact with the expandable gripping ring161, as well as a flared inner surface corresponding to the external flared outer surface of the locking ring310. With the longitudinal movement of the internal rod321, the back-pushing ring160and the expandable gripping ring161, the continuous expandable sealing ring170may follow the same movement, namely a longitudinal displacement together with a radial expansion along the flared outer surface of the locking ring310.

The locking ring310may not follow the same longitudinal movement as parts321,160,161and170, as the locking ring310may be stopped longitudinally relative to the external mandrel322thanks to the one or more studs312. The studs312may include two stopping surfaces on each of its extremity. One stopping surface of the stud312is symbolized with arrow333and corresponds to a similar stopping surface334positioned within the locking ring310. Another stopping surface on the longitudinal opposite direction of the stud312is symbolized with arrow332and may correspond to a stopping surface331positioned within the external mandrel322. Therefore, when a relative longitudinal movement is initiated between the internal rod321relative to the external mandrel322, the items161and170may move longitudinally with the internal rod321. During the longitudinal movement of the rod321, the locking ring310may be stopped or blocked longitudinally relative to the rod and stay at the same longitudinal position compared to the external mandrel322, thanks to the one or more studs312, which ensure the longitudinal blocking movement of the locking ring310relative to the external mandrel322.

An untethered object313such as a ball, dart or pill may be placed in an internal pocket323within the external mandrel322. Depending on the position of the blocking surface331of the external mandrel322compared to the blocking surface332of the stud312, the untethered object313may play a similar blocking surface role as surface331, if one of the studs312is positioned at a corresponding rotational angle in front of the untethered object313.

The hemispherical cup311may include trough-orifices which may let the longitudinal movement of the studs312. During the plug actuation, the blocking surfaces331,332,333and334may not interfere with the longitudinal equilibrium of the hemispherical cup311, and therefore the hemispherical cup311may not be constraint or displaced longitudinally during the plug actuation process nor during the relative movement340of the internal rod321relative to the external mandrel322.

FIG.8is a sequential view ofFIG.7.FIG.8represents a cross-section view of a set plug within the tubing string1and depicts the position of the internal rod321after the shearing the pre-loaded shearing devices65.

Sequential fromFIG.7,FIG.8represents the plug in a set position, wherein at least one anchoring device74is contacting and possibly penetrating the tubing string1. At this point, the force and displacement induced by the relative movement of the internal rod321compared to the external mandrel322is stopped and the force is concentrated within the shearing devices65. After reaching a force in the range of 1,000 lbf to 60,000 lbf [4450 N to 267,000 N], the shearing devices may shear and is represented as item66after shear inFIG.8. The internal rod321may continue its longitudinal movement341relative to the external mandrel322without affecting or solicitating the other parts of the now set plug, such as items160,161,170,310,312and311.

FIG.9represents a subsequent step fromFIG.8.FIG.9depicts a cross-sectional view of a set plug within a tubing string1, and the releasing of the toolstring including the setting adapter with the internal rod321and external mandrel322, movement symbolized with arrows342. The releasing of the setting adapter may occur after a pulling action from surface with the device connecting the toolstring, such as a cable, a coiled-tubing or tubing conveyance. The releasing of the setting adapter may also occur from a pumping back of well fluid2, or due to the movement self-capacity of the toolstring, such as with a tractor or turbine.

While the releasing of the setting adapter including the internal rod321and external mandrel322, the untethered object313may be free to be released inside the well fluid2. A flow channel315may contribute to the release of the untethered object313from the internal pocket323within the external mandrel322. Other devices such as a spring may contribute to the releasing of the untethered object313inside the well fluid2and towards the set plug. The set plug with all its components, such as the back-pushing ring160, the sheared shearing devices66, the expandable gripping ring161and its anchoring devices74, the expandable continuous sealing ring170, the locking ring310, the hemispherical cup311and the studs312, may stay set within the tubing string1and not move longitudinally within the tubing string1.

FIG.10represents a subsequent step ofFIG.9.FIG.10depicts a cross-section view of the set plug within the tubing string1, with the untethered object313now landed on the set plug. The untethered object313may follow a displacement from the internal pocket323of the external mandrel322towards a seat within the hemispherical cup311. The arrow343may symbolize a fluid flow of well fluid2contributing to the displacement of the untethered object313from the external mandrel322towards the hemispherical cup311. The fluid flow343may partially flow through the internal channel315of the external mandrel322. The fluid flow343may occur through the internal movement of well fluid2within the tubing string1, or through the pumping of well fluid2from surface.

FIG.11represents a subsequent step ofFIG.10.FIG.11depicts a cross-sectional view of the set plug inside the tubing string1with the untethered object313landed on the hemispherical cup311of the plug.FIG.11shows the retrieval of the toolstring including the setting adapter which may comprise the internal rod321and external mandrel322, previously depicted inFIG.10. InFIG.11the toolstring retrieval is symbolized with arrow344. The toolstring may perform other operation uphole of the set plug within the tubing string1and inside the well fluid2, such as fluid, formation or tubing measurement, tubing perforation, communication to another device within the same tubing string1or another tubing string, or back to surface.

With the landing of the untethered object313on the hemispherical cup311, the plug may provide a full or partial well fluid isolation, uphole to the set plug relative to downhole of the set plug. Further pumping of well fluid2, symbolized with arrows345, through the set plug, may be performed from surface or an internal well fluid2movement within the tubing string1.

FIG.12represents a subsequent step ofFIG.11.FIG.12depicts a cross-sectional view of the set plug inside the tubing string1with the untethered object313landed on the hemispherical cup311of the plug and the flowing or pumping of well fluid2, represented with arrows345, as inFIG.11.FIG.12shows the resultant of the flowing345of well fluid2through the set plug which is resulting in a local longitudinal force346due to the restricted flow of fluid within a limited flow-through area, creating a fluid pressure uphole of the restriction. The local created fluid pressure P may induce a force F on all exposed surface S, following the formula F=P/S, which is sometimes designated as a Venturi effect.

The local longitudinal force346may act on all surfaces exposed to the well fluid2, uphole of the set plug. Through the geometry of the plug components which will further be detailed inFIG.13, the force346may act longitudinally in particular on the untethered object313and the hemispherical cup311. The studs312may also be exposed to the local longitudinal force346, though may not be able to move longitudinally through the common contact of the blocking surface333on the studs312relative to the blocking surface334on the locking ring310. The local longitudinal force346on the untethered object131and on the hemispherical cup311may include a longitudinal movement of the two parts. The longitudinal movement of the hemispherical cup311may deform further radially a thin section of the locking ring310and in turn further deform radially the expandable continuous sealing ring170. Further details will be descripted inFIG.13.

FIG.13represents two detailed close-up views of cross-section of the set plug. The left view ofFIG.13represents a detailed close-up section ofFIG.11, while the right view ofFIG.13represents a detailed close-up section ofFIG.12. Both views show about the upper half cross-section of the set plug between the center line12and the tubing string1.

Left view ofFIG.13represent the plug set inside the tubing string1, with the expandable gripping ring161expanded including anchoring devices74in contact with the inner surface of the tubing string1. The untethered object313has just landed on the dedicated opening within the hemispherical cup311. The flowing of the well fluid2is represented with arrows345as onFIG.11.

Right view ofFIG.13represents the subsequent step of the left view ofFIG.13, after the well fluid flow345has been converted to a longitudinal force346on the surfaces exposed to well fluid uphole of the set plug. As explained in the description ofFIG.12, the studs312are prevented to move further longitudinally with the local longitudinal force346due to the blocking surface333on the stud312and corresponding blocking surface334on the locking ring310.

A longitudinal gap386is represented in the left view ofFIG.13. The longitudinal gap386is further described inFIG.24including the different geometrical surfaces involved for its presence. The longitudinal gap386may be a gap between the outer surface of the hemispherical cup311and the inner surface of the locking ring310. The longitudinal gap386may be retained during the plug actuation and set as depicted inFIGS.7-8, due to presence of the studs316blocking the relative movement of the locking ring310relative to the external mandrel322and therefore keeping the hemispherical cup311free of acting forces during the actuation process. At the time of the untethered object313landing on the hemispherical cup311, the longitudinal gap386may still be present, before the local longitudinal force346is acting on the hemispherical cup311together with the untethered object313. On the right view ofFIG.13, the longitudinal gap386has been closed with the longitudinal displacement of the hemispherical cup311relative to the locking ring310. The locking ring310may not move longitudinally due to the local longitudinal force346, as the locking ring may be stopped longitudinally by the contact with the expandable gripping ring161which itself may be stopped longitudinally due to the anchoring devices74contacting and penetrating the tubing string1.

The closing of the longitudinal gap386, as shown on the right view of theFIG.13, may be possible with the radial deformation of a thin section of the locking ring310. Therefore, the longitudinal movement of the hemispherical cup310may be possible through the action of the local longitudinal force346up to the closing of the longitudinal gap386while at the same time a radial deformation, symbolized with arrow351occurs through the thin section of the locking ring310. The radial deformation351may occur through the flared outer surface of the hemispherical cup311and corresponding flared thin section of the locking ring310, The radial deformation354may be transmitted to the expandable continuous sealing ring350which may have the possibility to deform further radially towards the inner surface of the tubing string and consequently may allow a better sealing of the outer surface of the expandable continuous sealing ring170with the inner surface of the tubing string1. The further radial expansion of the sealing ring170is symbolized with arrow350. The further radial expansion350may be beneficial to improve the sealing of the plug with the tubing string1, specially for example in situation where the sealing ring170is built only with a metallic alloy, resulting in a metal-to-metal sealing feature, or if the inner surface of the tubing string1includes some surface irregularities such as scratches or scale build-up, or also if some small particles are present inside the well fluid, such as grains of sand.

After reaching the point where the longitudinal gap386is closed, and further force346is applied on the hemispherical cup311and untethered object313, the further force346may be finally transmitted towards the expandable gripping ring161and further enhance the further penetration of the anchoring devices74inside the inner surface of the tubing string1. The further penetration of the anchoring devices74is symbolized with arrow352. The further penetration352may be beneficial for the stability of the expandable gripping ring161and therefore of the whole plug while being solicitated with the local longitudinal force346which may further be completed with further greater longitudinal force due to pressure differential created from the pumping of well fluid2inside the tubing string1, in order to perform an operation inside the wellbore or formation, such as fracturing, acid pumping, treating fluid pumping. Typical pressure differential uphole compared to downhole of the plug may be in the range of 1,000 to 20,000 psi [6.9 MPa to 138 MPa].

FIG.14represents an isometric view of a plug in an unset position, such as the one depicted in cross-section view inFIG.6. The untethered object313as well the adapter kit with the internal rod321and external mandrel322are not represented in this view ofFIG.14. Visible are the hemispherical cup311, with four studs312. Note that other quantity of studs312within the hemispherical cup311may be possible, typically from one to twelve, and keeping the same function described inFIGS.6-13. Also visible is the outer flared surface of the locking ring310, the expandable continuous sealing ring170, the expandable gripping ring161represented with a plurality of segments, typically a quantity between 4 and 16 segments, and included anchoring devices74, typically between one and ten anchoring devices74within each segment of the expandable gripping ring161. A back-pushing ring160is represented as well, the back-pushing ring160may be linked to pre-loaded shearing device not visible in this view. The plug may include several axisymmetric features along the axis12. The plug may be placed in a well fluid2. Any or all components of the plug, including the untethered object further shown inFIG.15, may be built out of dissolving material reacting with the well fluid2.

FIG.15represents an isometric view of a plug in a set position, such as the one depicted in cross-section view inFIG.10, after the landing of the untethered object313. The continuous expandable sealing ring170is now expanded over the locking ring310. The expandable gripping ring161is expanded with the separation of the plurality of segments depicted inFIG.14. The back-pushing ring160may be present at the back of the set plug. The studs312and hemispherical cup311may have not moved longitudinally relative to the locking ring310and may be in the same position as depicted inFIG.14.

FIG.16represents an isometric view of a plug in a set position, such as the one depicted in cross-section view inFIG.12, after the action of the local longitudinal force346over the hemispherical cup311and the untethered object313, as described inFIG.12. Compared toFIG.15, the hemispherical cup311and untethered object313may have move longitudinally relative to the locking ring310. A further expansion of the expandable continuous sealing ring170may have occurred as described in the right view ofFIG.13. The other components of the plug may have not noticeably moved compared to the view ofFIG.15.

FIG.17represents an isometric view of an unset plug such as inFIG.14, though from another direction view and including the setting adapter with the internal rod321and the external mandrel322.

FIG.18represents an isolated isometric view of the hemispherical cup311, over the center axis12. Noticeable are four orifices or through-holes363dedicated to fit four studs312. Another orifice or through-hole positioned along the center axis12is a passage to let the internal rod321pass through. On the uphole side of the through-hole364, a chamfer or seating feature may be added to fit the profile of the untethered object313. On the downhole external face, two surfaces may be present. A first flared cup outer surface361may include a flared profile or angle corresponding to a first flared locking ring inner surface381of the locking ring310, as further described inFIGS.22-24. A second flared cup outer surface362may have a hemispherical profile corresponding to a similar second flared locking ring inner surface382on the locking ring310, as further described inFIGS.22-24.

FIG.18represents an isolated isometric view of the stud312, over the center axis12. The stud312may have the shape of a rod with an external surface373corresponding to the orifice or through-hole363of the hemispherical cup311. The stud312may include a seal372such as an O-ring to improve the sealing under pressure between the surface373of the stud312and the surface363of the hemispherical cup311, while ensuring a possible relative longitudinal sliding of the two parts. Two end surfaces371and374may represent the end surfaces of the rod shape and may correspond to the blocking surfaces332and333as described inFIGS.7,12and13. The end surfaces371and374may typically be flat and perpendicular to the center axis12, though may also include a small angle or orientation features to provide an alignment and force transmission guide with the corresponding surface on the external mandrel322, for surface371, and with the corresponding surface383on the locking ring310, for surface374. Possible and not represented would be to include a collet or shoulder feature on either side or both sides of the two end surfaces371and374. The collet feature may be added to limit the longitudinal span of longitudinal movement of the stud312relative to the hemispherical cup311, in either or both directions.

FIG.20represents an isometric view of the combination of the hemispherical cup311with four studs312. The represented position of the studs312relative to the hemispherical cup311may be the one of the unset plug as represented inFIG.6orFIG.14.

FIG.21represents an isometric view of the combination of the hemispherical cup311with four studs312, towards another view point direction compared toFIG.20.

FIG.22represents an isolated isometric view of the locking ring310, over the center line12. The locking ring310may include the first flared locking ring inner surface381. The first flared locking ring inner surface381may be conical or hemispherical, and may have a corresponding profile as the first flared cup outer surface361of the hemispherical cup311. Further downhole, the second flared locking ring inner surface382may be in the continuity of the first flared locking ring inner surface381. The second flared locking ring inner surface382may be hemispherical or conical, with a leading angle or curvature which may be tighter or further closing compared to the leading angle of curvature of the first flared locking ring inner surface381. A flared locking ring outer surface384of the locking ring310may have a flared profile such as conical or hemispherical. The profile of the flared locking ring outer surface384may correspond to the inner profile of the expandable continuous sealing ring170and to the inner profile of the expandable gripping ring161. The design of the locking ring310may include a thin section378, as further displayed inFIG.23, between the first flared locking ring inner surface381and the flared locking ring outer surface384, which may be in the range of 0.01 inch to 0.5 inch [0.2 mm to 12.7 mm], allowing a potential radial deformation as described in the details ofFIGS.12and13. The radial expansion diameter may be in the order of 1% to 30% expansion compared to the initial diameter of the thin surface.

The locking ring310may include one or several locking surfaces383, which may correspond to the end surface374of the studs312. A through hole385may be present around the center axis12of the locking ring310, in order for example to keep space for the passage for the rod321.

FIG.23represents an isolated isometric cross-section view of the locking ring310, over the center line12. The same features as the ones described inFIG.22are visible. In particular, the first flared locking ring inner surface381, the second flared locking ring inner surface382, the flared locking ring outer surface384. The thin section378between the first flared locking ring inner surface381and the flared locking ring outer surface384is represented inFIG.23. Also visible is the one or several locking surfaces383and the trough hole385.

FIG.24represents an isometric cross-section view of the combination of the locking ring310, the hemispherical cup311and the studs312, over the center line12.

FIG.24represents the configuration of the locking ring310the hemispherical cup311and the studs312, as those parts would be interfering in an unset plug or just set plug configuration, as would previously be shown inFIGS.6-10orFIGS.14-15. In this configuration, a longitudinal gap386may be present and not yet closed as would be the case inFIG.12orFIG.16. The longitudinal gap386may be present between the second flared cup outer surface362of the hemispherical cup311and the second flared locking ring inner surface382of the locking ring310. The studs312may be inserted inside the through-holes of the hemispherical cup311, and inner surface363may be at the proximity of the outer surface373of the studs312. The seal372may enhance the sealing capacity between those surfaces363and373and therefore potentially provide some pressure tightness, for fluid or gas, between the hemispherical cup310and the one or more studs312. In this position, the end surface374of the studs312may be in contact with the stopping surface383of the locking ring310, preventing a relative longitudinal movement towards each other parts.

The first flared cup outer surface361of the hemispherical cup311may match geometrically the conical lead angle, or the hemispherical lead profile of the first flared locking ring inner surface381of the locking ring310. Also visible is the flared locking ring outer surface384of the locking ring310, the through-hole365of the hemispherical cup311and the through-hole385of the locking ring310. The end surface371of the studs312may be even or slightly prominent with the external front surface of the hemispherical cup311. The position of the end surface371may allow the studs312to be in contact with the external mandrel322during the plug conveyance and setting as displayed inFIGS.6to8.

FIG.25represents a technique sequence390, which includes major steps described inFIG.6toFIG.12.

Step391corresponds to the deployment of a plug assembly, as depicted inFIG.6, over a retrievable setting tool, which may include an external mandrel322and an internal rod321. The plug assembly includes a carried untethered object313and a longitudinal stopping mechanism, such as studs312, as depicted inFIG.6toFIG.24. The deployment of the plug assembly is occurring into a tubing string1, which contains well fluid2.

Step392corresponds of the setting of the plug assembly, using the action of the retrievable setting tool which includes parts322and321. In particular step392includes the radial deformation of the expandable continuous seal ring170to an outer diameter which is less than the inner diameter of the tubing string1. Step392also include the expansion of the expandable gripping ring161over the locking ring310and the hemispherical cup311. During the expansion of the gripping ring161and the deformation of the expandable continuous seal ring170, the longitudinal stopping mechanism, materialized with studs312, is stopping the relative displacement of the locking ring relative to the retrievable setting tool and in particular relative to the external mandrel322.

Step393corresponds to the retrieval of the retrievable setting tool, including parts322and321.

Step394corresponds to the release of the carried untethered object313from the retrievable setting tool, typically from the external mandrel322. Alternatively, the untethered object313may be released or launched from surface inside the tubing string.

Step395corresponds to the contact of the untethered object313with the receiving inner surface of the hemispherical cup311.

Step396corresponds to the fluid further actuation of the set plug within the tubing string1and using well fluid2. The pressure and flow restriction of the well fluid2may press on the hemispherical cup311and on the untethered object313, which induces a longitudinal displacement and force of the two parts311and313, towards the downhole direction, and relative to the locking ring310. Further, the longitudinal displacement and force of the hemispherical cup311may induce the radial deformation of the locking ring310, in particular the thin section378between surfaces381and384as depicted inFIG.24. The radial deformation of the locking ring310induces in turn the radial deformation of the continuous expandable sealing ring170, potentially to improve the outer surface contact of the continuous expandable sealing ring170with the inner surface of the tubing string1, as well as enhance the anchoring action the contact and deformation of the expandable gripping ring161. Further, a downhole operation may be performed.