OA12087A - Lock assembly. - Google Patents

Abstract

A lock assembly (1) for locking an outer tubular element to an inner tubular element extending through the outer tubular element, the assembly comprising a lock mandrel (5) connected to one of said tubular elements and being provided with a recess facing the other one of said tubular elements, the recess (10) having at least one inwardly diverging side surface (12, 14), a lock member (34) arranged between the first and second tubular elements in a locking relationship with the other one of the tubular elements, the lock member extending into said recess and being operable between a retracted mode in which the lock member is movable relative to the recess and an expanded mode in which the lock member is expanded against the inwardly diverging side surface, the assembly further comprising an actuator means for expanding the lock member in said recess against said diverging side surface.

Description

1 2087

The présent invention relates to a lock assembly forlocking an outer tubular element to an inner tubularelement extending through the outer tubular element. Suchlock assemblies are, for example, applied in a wellborefor the production of hydrocarbon fluid from an earthformation. In such application the outer tubular elementcan be connected to (or integrally formed with) thewellbore casing or a wellbore production tubing, and theinner tubular element is adapted to receive a wellboredevice (e.g. a valve). A problem with such applications cornes to light whenthe lock assembly is subjected to longitudinal forces.

For example, when the inner element is subjected to alongitudinal force due to fluid pressure of producedhydrocarbon fluid, such force can lead to relativemovement between the two éléments leading to loosening ofthe lock connection. Furthermore, such relative movementprevents adéquate transmission of signais, e.g. acousticor electric signais, between the inner and outer tubularéléments. A further problem occurs with applicationsinvolving conventional dog and lock shoulders whereby theinner tubular element is subjected to radially inwardforces upon application of a pulling force, thusrequiring an increased wall thickness of the innertubular element.

Accordingly it is an object of the invention toprovide an improved lock assembly which overcomes theproblems of the conventional lock assemblies.

In accordance with the invention there is provided alock assembly for locking an outer tubular element to aninner tubular element extending through the outer tubular 1 2087 element, the assembly comprising a lock mandrel connectedto one of said tubular éléments and being provided with arecess facing the other one of said tubular éléments, therecess having at least one inwardly diverging side 5 surface, a lock member arranged between the first and second tubular éléments in a locking relationship withthe other one of the tubular éléments, the lock memberextending into said recess and being opérable between aretracted mode in which the lock member is movable 10 relative to the recess and an expanded mode in which the lock member is expanded against the inwardly divergingside surface, the assembly further comprising an actuatormeans for expanding the lock member in said recessagainst said diverging side surface. 15 It is thereby achieved that when the lock member is in the expanded mode, a load applied to the lockassembly, e.g. a longitudinal pulling force, induces thelock member to become even more firmly locked in therecess due to the inwardly diverging side surface of the 20 recess. Thereby the locking action of the assembly is enhanced. Furthermore, it is thereby ensured that theinner and outer éléments are in firm contact with eachother allowing adéquate transmission of electric oracoustic signais. 25 The invention will be described hereinafter in more detail with reference to the accompanying drawings inwhich:

Fig. 1 schematically shows a first embodiment of awellbore assembly according to the invention; 30 Fig. 2 shows detail A of Fig. 1 in a first mode of operation;

Fig. 3 shows detail A of Fig. 1 in a second mode ofoperation;

Fig. 4 schematically shows a lock member for use in 35 the first and second embodiments; 3 1 2087

Fig. 5 shows the lock member of Fig. 4 in anothermode of operation; and

Fig. 6 schematically shows a second embodiment of awellbore assembly according to the invention;

In the detailed description below like reference -Mte. t numerals relate to like components.

Referring to Fig. 1 there is shown a lock assembly 1extending in a wellbore (not shown) formed in an earthformation, the assembly 1 having a central longitudinalaxis 2 substantially coinciding with the with thelongitudinal axis of the wellbore. The lock assembly issymmetrical with respect to axis 2, therefore only onehalf of the lock assembly is shown in Fig. 1. The lockassembly includes an outer tubular element in the form ofa wellbore casing 3 arranged in the wellbore. A lockmandrel 5 is connected to the casing 3 by welds 7, 8 soas to form an intégral part of the casing 3.

Referring in more detail to Fig. 2, an annularrecesses 10 is formed in the casing 3 at the innersurface thereof, the recess 10 having outwardly divergingside surfaces 12, 14 arranged opposite each other and anend surface 15 extending parallel to the longitudinalaxis 2.

An inner tubular element 16 is concentricallyarranged within the casing 3, the inner tubularelement 16 including a first actuating member 18, asecond actuating member 20, and a rotatable sleeve 22 inco-operating arrangement with the first actuating memberby means of a left hand threaded connection 24 and in co-operating arrangement with the second actuating member 20by means of a right hand threaded connection 26. As shownmore clearly in Fig. 2, an annular space 28 of variablelength is thereby defined between the actuatingmembers 18, 20. Thus upon rotation of the sleeve 22, theactuating members 18, 20 move relative to each other in (2 087 longitudinal direction between an extended mode in whichthe space 28 is relatively long and a retracted mode inwhich the space 28 is relatively short. The location ofthe inner tubular element 16 relative to the recess 10 issuch that the centre of space 28 is located opposite thecentre of recess 10. The ends of the actuatingmembers 18, 20 facing the space 28 hâve end surfaces 30,32 diverging in outward direction.

Two or more lock members 34 (only one of which isshown) are arranged in the annular space 28, the lockmembers 34 being interconnected by one or more circularsprings 35 acting as retracting springs keeping the lockmembers in place against actuating members 18, 20.

As shown in more detail in Figs. 4 and 5, each lockmember 34 includes a first part 36 and a second part 38,the parts 36, 38 being mutually rotatable about a rod 40extending in circumferential direction. The rod 40 can bean intégral part of one of the lock members 34. Part 36has an outer surface 41a, an outer side surface 41b, andan inner side surface 41c. Part 38 has an outersurface 42a, an outer side surface 42b, and an inner sidesurface 42c.

The parts are held together by a leaf spring 44biasing the parts 36, 38 to a retracted position in whichthe outer surfaces 41a, 42a extend at an angle so as toform a concave radially outer end of the lock member 34.The dimensions of the lock member 34 are such that thelock member is capable of passing into the recess 10 whenthe parts 36, 38 are in the retracted position.

Referring to Fig. 3, the orientation of the outerside surfaces 41b, 42b is such that when the parts 36, 38are rotated to an expanded position (shown in Fig. 5) inwhich the outer surfaces 41a, 42a are aligned, the lockmember 34 fits in the recess 10 whereby the outersurfaces 41a, 42a are in contact with the radially outer 5 1 2087 surface 15 of the recess, and wherein the outer sidesurfaces 41b, 42b are in contact with the respective sidesurfaces 12, 14 of the recess 10. Furthermore, theorientation of the inner side surfaces 41c, 42c is suchthat when the parts 36, 38 are rotated to the expandedposition the inner side surfaces 41c, 42c are in contactwith the respective end surfaces 30, 32 of the actuatingmembers 18, 20.

The second actuating member 20 is provided with anorienting/holding slot 50 (Fig. 1) for orienting andholding an actuator (not shown) in the inner tubularelement 16. A wellbore tool (not shown), for example adownhole production valve or a downhole safety valve, isconnected to the actuating member 18. The first actuatingmember 18 is internally provided with a set of primaryslots 54 and the sleeve 22 is provided with a set ofsecondary slots 56. The actuator is adapted to engage theslot 50 and includes two parts rotatable relative to eachother, each part having a set of fingers capable ofgripping into the respective sets of slots 54, 56.

During normal operation the inner tubular element 16is lowered into the wellbore casing 3 with the actuatorattached thereto, and whereby the actuating members 18, 20 are in the extended mode thereby allowing the leafspring 44 of each lock member 34 to retract the lockmember parts 36, 38 to their retracted position. Loweringis stopped when the lock members 34 are positionedopposite the annular recess 10, as shown in Fig. 2. Theactuator is then activated whereby the sets of fingers ofthe actuator grip into the respective sets of slots 54,56. The two actuator parts are then rotated relative toeach other so as to rotate the sleeve 22 in a directionthat the first and second actuating members 18, 20 moverelative to each other to the retracted mode. As a resuitthe diverging end surfaces 30, 32 of the actuating 6 1 2 087 members push each lock member 34 into the recess 10whereby the outer surfaces 41a, 42a of the respectivelock member parts 36, 38 contact the end surface 15 ofthe recess 10. Upon further rotation of the sleeve 22the parts 36, 38 rotate relative to each other around therod 40 until the lock member 34 becomes in the expandedposition in which the outer surfaces 41a, 42a are alignedand in full contact with the end surface 15, and theouter side surfaces 41b, 42b are in full contact with therespective side surfaces 12, 14 of the recess 10. In thisposition the lock members 34 are locked into therecess 10.

It is thus achieved that a form fit connectionbetween the inner tubular 16 and the casing 3 is created,which provides an excellent acoustic or electrical link.In case the wellbore tool or the inner tubular element 16are subjected to a longitudinal force, for example due topressure of hydrocarbon fluid flowing through thewellbore, the lock members 34 become even more firmlylocked into the recess 10 due to the outwardly divergingshape of the recess 10 and lock member 34. It is therebyprevented that the connection between inner tubularelement 16 and casing becomes loose or that the innertubular element 16 collapses due to inward movement ofthe lock members. Furthermore, the tight connectionensures that acoustic signais for wellbore control orinformation transfer are adequately transferred betweenthe inner tubular element 16 and the casing 3.

Reference is further made to the second embodiment ofthe lock assembly according to the invention, as shown inFig. 6. The lock assembly is symmetrical with respect tolongitudinal axis 58, therefore only one half of the lockassembly is shown in Fig. 6. The second embodiment islargely similar to the first embodiment, except that thesleeve for moving the actuating members 18, 20 relative 7 1 2087 to each other has been replaced by a set of shaped memoryalloy actuators 60 (hereinafter referred to as SMAactuators), whereby one end of each SMA actuator 60 isfixedly connected to actuating member 18 by fasteners 62,and the other end of the SMA actuator is fixedlyconnected to actuating member 20 by fasteners 64. EachSMA actuator 60 has a transition température above whichthe SMA actuator has an increased length, and below whichthe SMA actuator has a reduced length. The sets ofslots 54, 56 of the first embodiment are absent in thesecond embodiment.

Normal operation of the second embodiment is similarto normal operation of the first embodiment, except thatinstead of using the actuator tool to move the actuatingmembers 18, 20 relative to each other, such movement isinduced by contraction of the SMA actuators. This isachieved by installing a heater (not shown) in the innertubular element 16 and opérâting the heater duringlowering of the inner tubular element 16 into the casingso that the température of the SMA actuators is above thetransition température. Thereafter the heater is turnedoff so that the température of the SMA actuators dropsbelow the transition température whereby the SMAactuators contract and thereby move the actuatingmembers 18, 20 to their retracted mode.

Claims (12)

1. 8 1 2087

   1. A lock assembly for locking an outer tubular elementto an inner tubular element extending through the outertubular element, the assembly comprising a lock mandrelconnected to one of said tubular éléments and beingprovided with a recess facing the other one of saidtubular éléments, the recess having at least one inwardlydiverging side surface, a lock member arranged betweenthe first and second tubular éléments in a lockingrelationship with the other one of the tubular éléments,the lock member extending into said recess and beingopérable between a retracted mode in which the lockmember is movable relative to the recess and an expandedmode in which the lock member is expanded against theinwardly diverging side surface, the assembly furthercomprising an actuator means for expanding the lockmember in said recess against said diverging sidesurface.
2. 2. The lock assembly of claim 1, wherein the lockmandrel is connected to the outer tubular element.
3. 3. The lock assembly of claim 1 or 2, wherein saiddiverging side surface extends in circumferentialdirection of the lock mandrel.
4. 4. The lock assembly of claim 3, wherein the recess hastwo said inwardly diverging side surfaces arrangedopposite each other.
5. 5. The lock assembly of claim 3 or 4, wherein the lockmember includes a first part and a second part rotatablerelative to the first part about an axis extendingsubstantially in circumferential direction, and whereinthe lock member is opérable between the retracted mode 9 1 2087 and the expanded mode by rotating said parts relative toeach other.
6. 6. The lock assembly of claim 5, further comprisingspring means biasing said parts to the retracted mode.
7. 7. The lock assembly of claim 5 or 6, wherein theactuator means comprises a first actuator member and asecond actuator member, the actuator members beingmovable relative to each other in longitudinal directionof the tubular éléments and being arranged so as torotate said parts relative to each other upon saidrelative movement of the actuator members, and a controldevice for controlling said relative movement of theactuator members.
8. 8. The lock assembly of claim 7, wherein the firstactuator member is in contact with said first part at aprimary contact surface, and the second actuator memberis in contact with said second part at a secondarycontact surface, said contact surfaces diverging inradial direction towards said recess.
9. 9. The lock assembly of claim 7 or 8, wherein thecontrol device comprises a rotatable sleeve in co-operating arrangement with the first actuator member bymeans of a left hand thread connection and in co-operating arrangement with the second actuator member bymeans of a right hand thread connection.
10. 10. The lock assembly of any one of daims 7-9, whereinthe actuator means comprises a memory métal elementinterconnecting the first and second actuator members andbeing opérable between a longitudinally retracted modeand a longitudinally extended mode.
11. 11. The lock assembly of any one of daims 1-10, whereinsaid tubular éléments are arranged in a wellbore formedin an earth formation. 10 1 2087
12. 12. The lock assembly substantially as describedhereinbefore with reference to the accompanying drawings