OA11798A

OA11798A - Wellbore system including a conduit and an expandable device.

Info

Publication number: OA11798A
Application number: OA1200100109A
Authority: OA
Inventors: Wilhelmus Hubertus P M Heijnen
Original assignee: Shell Int Research
Priority date: 1998-11-04
Filing date: 1999-11-01
Publication date: 2005-08-10
Also published as: ID29483A; AU757221B2; GC0000080A; EP1133617B1; CA2349188A1; DE69920261T2; EG22610A; BR9915064A; CN1258635C; WO2000026501A1; CN1325478A; NO20012189D0; EA200100495A1; NO320696B1; AU1382800A; CA2349188C; EP1133617A1; NO20012189L; DE69920261D1; EA003241B1

Abstract

A system is provided including a conduit having a longitudinal axis, and a device (30) which is radially expandable relative to the conduit from a retracted mode whereby the device is radially spaced from the conduit, to an expanded mode whereby the device is radially expanded against the conduit. The device includes a shape memory metal element transformable from a first shape to a second shape upon reaching a selected temperature, the shape memory metal element being arranged to expand the device from the retracted mode to the expanded mode upon transformation of the memory metal element from the first shape to the second shape.

Description

1

WELLBORE SYSTEM INCLUDING A CONDUIT AND AN EXPANDABLE DEVICE

The présent invention relates to a System including aconduit having a longitudinal axis, and a device which isradially expandable relative to the conduit from aretracted mode whereby the device is radially spaced from 5 the conduit, to an expanded mode whereby the device is radially expanded against the conduit. Systems of thiskind are used, for example, in the industry ofhydrocarbon production from the earth formation wherebyexpandable devices such as expandable packers or

10 expandable anchors are applied in wellbore tubulars. A problem frequently occurring in such applications relatesto the generally contradicting operational requirementsfor the expandable devices. Namely, in the retracted modethe device must be freely movable relative to the conduit 15 in order to install the device at the desired location, and in the expanded mode the device must providesufficient axial holding power (for e.g. wellborepackers) or sealing capacity (for wellbore seals). Theproblem is even more pronounced for applications in which 20 the device is to be installed at remote locations.

It is an object of the invention to provide animproved expandable System which can be adequately radially expanded from a retracted mode to an expandedmode relative to a conduit, even at remote locations, and 25 which provides adéquate axial holding power and/or sealing capacity for high pressure applications.

In accordance with the invention there is provided a

System including a conduit having a longitudinal axis, and a device which is radially expandable relative to the 30 conduit from a retracted mode whereby the device is radially spaced from the conduit, to an expanded mode 2 117 9 8 whereby the device is radially expanded against theconduit, wherein the device includes a shape memory métalelement transformable from a first shape to a secondshape upon reaching a selected température, the shapememory métal element being arranged to expand the devicefrom the retracted mode to the expanded mode upontransformation of the memory métal element from the firstshape to the second shape.

When the device is in the retracted mode, the spacingbetween the device and the conduit allows axial movementof the device relative to the conduit during installationof the device. By subsequently heating or cooling of thememory métal element so that the température of thememory métal element reaches the selected température,the memory métal element transforms from the first shapeto the second shape and thereby expands the device fromthe retracted mode to the expanded mode. Furthermore, nocomplicated remote controlled expansion equipment isneeded to expand the device, only a heating or coolingsource is applied. The memory métal element is capable ofproviding a large force upon transformation so thatadéquate holding power can be achieved and/or, when thedevice and the conduit are made of métal, a reliablemetal-to-metal seal is achieved by the expansion of thedevice against the conduit.

Suitably said conduit is one of an outer conduit andan inner conduit extending coaxially into the outerconduit whereby an annular space is defined between theouter conduit and the inner conduit, and wherein theexpandable device forms a sealing device arranged in saidannular space, which sealing device in the radiallyexpanded mode thereof is expanded against said innerconduit and against said outer conduit.

In an attractive embodiment the System further includes a branched wellbore System formed in an earth 3 117 9 8 formation, the branched wellbore System comprising a mainwellbore provided with a main casing, a branch wellboreprovided with a branch casing, and a casing junctionmember having a main bore and a branch bore in fluidcommunication with the main bore, the main bore being anextension of the main casing, the branch bore being anextension of the branch casing, and wherein said innerconduit is formed by the branch casing and the outerconduit is formed by the branch bore. This embodiment isparticularly attractive as it provides an adéquatesolution to the problem of sealing of wellbore junctionsof multilatéral wellbore Systems. US patent No. 5,318,122 discloses a Y-shaped casingjunction member which connects a casing of a mainwellbore to a liner installed in a branch wellbore, thecasing junction member having a branch member into whichan end part of the liner extends with a seal between saidend part and the branch member. However a problem of theknown System is that a reliable seal which is capable ofwithstanding the high wellbore pressures generallyencountered, is not available. Therefore the known casingjunction has to be positioned relatively deep in the mainwellbore, i.e. in the réservoir zone or in the cap rockoverlaying the réservoir zone, where the fluid pressuredifférence between the interior and the exterior of thecasing is relatively low and where leaks are unimportant.In this respect it is noted that the cap rock layer hassufficient low permeability to prevent migration offluids from the réservoir zone to the overburden layerabove the cap rock.

In contrast thereto the system according to theinvention allows the casing junction member to bepositioned anywhere, and preferably relatively high inthe main wellbore, i.e. in the overburden layer. This isadvantageous because the branch wellbore then starts 117 9 8 deviating from the main wellbore relatively high in theearth formation so that, for a given maximum curvature ofthe branch wellbore, the lower end of the branch wellborecan be drilled to a larger horizontal distance from themain wellbore than in a conventional situation where thejunction between the main wellbore and the branchwellbore is located in the réservoir zone or the cap rocklayer. Thus, by virtue of the large sealing capacityachieved with the System according to the invention thejunction between the main wellbore and the branchwellbore can be positioned in the overburden layer wherethe différence between the pore pressure in the overburden layer and the pressure of hydrocarbon fluidflowing through the wellbore System, is high.

It is preferred that the sealing device in theexpanded position thereof provides a metal-to-metal seal.

In another attractive embodiment, the device is ananchoring device arranged within the conduit and adaptedto be anchored to the inner surface of the conduit whenin the radially expanded mode.

The invention will be described hereinafter by way ofexample in more detail with reference to the accompanyingdrawings in which:

Fig. 1 schematically shows an embodiment of awellbore System according to the invention;

Fig. 2 schematically shows a casing junction memberof the System of Fig. 1;

Fig. 2A schematically shows transverse cross-sectionalong line 2A-2A of Fig. 2;

Fig. 2B schematically shows transverse cross-sectionalong line 2B-2B of Fig. 2;

Fig. 3 schematically shows the casing junction memberof Fig. 2 in a sealed mode;

Fig. 4 schematically shows detail A of Fig. 3; and 5 117 9 8

Fig. 5 schematically shows a further embodiment ofthe wellbore System according to the invention.

Referring to Fig. 1 there is shown a wellboreSystem 1 including a main wellbore 3 extending from awellhead 5 at the earth surface 7 through an overburdenlayer 9 and a cap rock layer 11 to a réservoir zone 14which contains a hydrocarbon fluid. The cap rock layer 11is relatively tight and prevents migration of the highpressure hydrocarbon fluid from the réservoir zone 14 tothe overburden layer 9.

The main wellbore 3 is provided with a tubular Steelmain casing 16 which is fixed and sealed into the mainwellbore 3 by a layer of cernent 17 and which has an openlower end. A branch wellbore 18 extends from a wellborejunction 19 located in the overburden layer 9, throughthe overburden layer 9 and the cap rock layer 11, intothe réservoir zone 14. The branch wellbore 18 is providedwith a branch casing 20 having an open lower end andbeing connected to the main casing 16 by a casingjunction member 22 in a sealing relationship therewith asdescribed below. The casing junction member 22 is locatedat the wellbore junction 19, i.e. in the overburdenlayer 9. The branch casing 20 is sealed into the branchwellbore 18 by a layer of cernent 24. Alternatively thebranch casing can be sealed in the branch wellbore by anysuitable means such as by sealing packers.

Referring further to Figs. 2, 2A, 2B and 3, thecasing junction member 22 has a tubular main bore 24having longitudinal axis 24a, the main bore 24 beingaligned with the main casing 16, and a tubular branchbore 26 having longitudinal axis 26a. The branchcasing 20 extends into the branch bore 26 with an annularspace 28 therebetween. An annular sealing device 30 isarranged in the space 28, which sealing device 30 ismovable between a radially retracted mode and a radially 6 117 9 8 expanded mode. In the retracted mode the sealing deviceis radially spaced from the branch bore 26 and from thebranch casing 20 as shown in Fig. 2. In the expanded modethe sealing device 30 is expanded against the branch bore26 and the branch casing 20 as shown in Fig. 3.

The casing junction member 22 is a monolithicstructure and has a generally circular transversecross-section, as shown in Figs. 2A and 2B, Suchstructure and shape provide adéquate collapse résistanceto the casing junction member 22, which should not beless than the collapse résistance of the main casing 16,

In Fig. 4 is shown detail A of Fig. 3. The sealingdevice 30 includes a métal annular body 34 having twosealing rings 36a, 36b and an annular wedge 38 which isarranged between the sealing rings 36a, 36b and is inoperative relationship therewith so as to radially presssealing ring 36a against the branch bore 26 and sealingring 36b against the branch casing 20 upon axial movementof the wedge 38 into the annular· body 34. The contactsurfaces between the wedge 38 and the sealing rings 36a,36 b are serrated so that the wedge becomes locked to thesealing rings once such inward axial movement hasoccurred. A number of circumferentially spaced rods 40extend through corresponding holes 41 provided in thewedge 38, each rod having a threaded end 40a connectingthe rod to the annular body 34 and a T-shaped head 40b atthe other end. The rods 40 are made'of shape memory métaland assume an axially extended shape below a selectedtransition température and an axially retracted shapeabove the transition température. In the axially extendedshape, the wedge 38 is in an initial position wherebysealing ring 36a is radially spaced from the surface ofthe branch bore 26 and sealing ring 36b is radiallyspaced from the outer surface of the branch casing 20. Inthe axially retracted shape of the rods 40, the wedge 38 117 9 8 is pulled by the rods between the sealing rings 36a, 36bwhereby sealing ring 36a becomes pressed against thesurface of the branch bore 26 and ring 36b against outersurface of the branch casing 20 so as to form a metal-to-metal seal between the branch bore 26 and the branchcasing 20. Annular body 34 is connected to a lock nut 42by a bearing 44 which allows rotation of the lock nut 42relative to the body 34 about longitudinal axis 26a. Locknut 42 is connected to the branch casing 20 by screwconnection 46.

Fig. 4 furthermore shows a locking and centralisingassembly 48 arranged between the branch bore 26 and thebranch casing 20, the assembly 48 including a self-expanding lock ring 50 which is supported on a shapememory métal actuator ring 52 which in turn is supportedon a tapered landing ring 54. The landing ring 54 restsagainst an annular shoulder 55 provided at branchcasing 20 and has an outer annular groove 56 in which asplit actuator ring 58 of shape memory métal is arranged.The assembly 48 is retained between an annular retainingring 60 and an annular shoulder 62 provided at the outersurface of the branch casing 20. The retaining ring 60can be shrink fitted, screwed, snap fitted or welded tothe branch casing 20. The actuator ring 52 assumes anaxially retracted shape below a selected transitiontempérature and an axially extended shape above thetransition température. The split actuator ring 58assumes a radially retracted shape below the selectedtransition température and a radially extended shapeabove the transition température. An annular groove 64 isprovided in the branch bore 26, into which theassembly 48 fits with some axial and radial clearance ifthe actuator rings 52, 58 are below their transitiontempérature. If the actuator rings 52, 58 are above theirtransition température the lock ring 50 is pressed 8 117 9 8 against shoulder 62 by the axially expanded actuatorring 52, and the landing ring 54 is centralised in thebranch bore 26 by the radially expanded actuator ring 58.The transition température of the actuator rings 52, 58is selected slightly below the transition température ofthe rods 40.

During normal operation of the wellbore System 1, themain wellbore 3 is drilled and the main casing 16 withthe casing junction member 22 incorporated therein islowered and cemented into the main wellbore 3. During theinstallation and cementing procedure the branch bore 26is at the lower end thereof closed by a plug (not shown)which can be drilled out. A whipstock (not shown) is thenpositioned in the main casing 16 and casing junctionmember 22 so as to direct a drill string (not shown) intothe branch bore 26. A removable wear bushing (not shown)is temporarily arranged in the branch bore 26 to preventcontact of the drill string with the surface of thebranch bore 26. The drill string is then lowered throughthe main casing 16 and guided by the whipstock into thebranch bore 26. The drill string is rotated to drill outthe plug and to drill the branch wellbore 18. Aftercompleting the drilling operation the wear bushing isremoved from branch bore 26 and the branch casing 20 islowered through the main casing 16 and guided by thewhipstock (or by any other suitable guiding means) intothe branch wellbore 18 until the self-expanding lock ring50 latches into annular groove 64. The branch casing issupported by landing ring 54 and shoulder 55.

The sealing device 30 is lowered through the maincasing 16 and guided into branch bore 26 whereby theannular body 34 enters the annular space 28 until locknut 42 arrives at the upper end of the branch casing 20.The lock nut 42 is then screwed to the branch casingusing a suitable setting tool (not shown) whereby the 9 11798 ’ bearing 44 allows the annuler body 34 to be non-rotatingwhile the lock nut is rotated. By virtue of the design ofthe sealing device 30, the wedge 38 and sealing rings 36a, 36b are accurately positioned in the annularspace 28. Reversai of the above procedure using thesetting tool allows the sealing device 30 to be withdrawnfrom the annular space 28, for example to install a newseal. A heating device (not shown) is lowered through themain casing 16 and guided into branch bore 26. Heat istransferred from the heating device to the shape memorymétal éléments 52, 58 and 40. Upon reaching theirrespective transition température actuator ring 52expands axially and actuator ring 58 expands radiallythereby axially locking and centralising branch casing 20in branch bore 26. The rods 40 axially retract uponreaching their respective transition température andthereby pull wedge 38 between the sealing rings 36a, 36bwhereby ring 36a becomes pressed against the surface ofthe branch bore 26 and ring 36b against the outer surfaceof the branch casing 20 so as to form a metal-to-metalseal between the branch bore 26 and the branch casing 20.The wedge 38 becomes locked to the rings 36a, 36b byvirtue of the serrated contact surfaces between thewedge 38 and the rings 36a, 36b. As the heating device isturned off and the température of the rods 40 drops belowthe transition température thereof, the rods axiallyexpand through the respective holes 41 of wedge 38 whilethe wedge remains locked to the sealing rings. Cernent ispumped between the branch casing 20 and the branchborehole 18 to form cernent layer 24 which seals thebranch casing in the branch borehole 18.

After completion of wellbore System 1, production of hydrocarbon fluid, e.g. high pressure natural gas, from the réservoir zone 14 is commenced. The fluid flows from 10 117 9 8 the réservoir zone 14 into the main casing 16 and thebranch casing 20 and through these casings to thewellhead 5 from where the fluid is further transported toa suitable processing facility (not shown). The metal-to-metal-seal provided by sealing device 30 prevents leakageof fluids through annular space 28 to the overburdenlayer 9. Cernent layers 17 and 24 seal the main casing 16and the branch casing 20 in their respective wellbores sothat leakage of gas from the réservoir zone 14 along thecasings 16, 20 to the overburden layer 9 also isprevented. In this manner it is achieved that gas isproduced through the casings 16, 20 without the need forconventional production tubings, and without the risk ofgas leaking from the réservoir zone 14 to the overburdenlayer 9.

Another advantage of the System of the invention isthe option of including a secondary conduit extendingfrom the wellhead (which is provided with a blow outpreventer) through the main casing and into the branchbore of the casing junction member in a sealingrelationship with said branch bore. The secondary conduitcan be, for example, a hydrocarbon fluid productionconduit for separate production of hydrocarbon fluid fromthe branch wellbore and main wellbore e.g. in case of ahigh fluid pressure différence between the main wellboreand the branch wellbore. Alternatively, the secondaryconduit can be a service Tiner for guiding a wellboretool from the earth surface into the branch wellbore,such as a drill string for further drilling of the branchwellbore. An advantage of the application of such serviceliner is that fluid production through the main wellboreis continued while wellbore operations in the branchwellbore are carried through the service liner whichisolâtes such operations from the remainder of the mainwellbore and any other branch wellbores thereof. The 11 117 9 8 secondary conduit is preferably provided with a latchingmechanism which latches into the branch bore.

Optionally the branch casing can be provided in itsupper end part with a flow control valve which isretrievable to surface by wireline or coiled tubing. Theflow control valve Controls the flow of hydrocarbon fluidthrough the branch casing and is operated by telemetry orby a selected property of the fluid under control.

Furthermore, a safety valve can be installed in thefar end part of the branch casing which opérâtes bytelemetry or by a property of the fluid under control,for example a selected fluid pressure différence acrossthe safety valve.

The flow control valve and the safety valve each hâvea reverse flow bypass which permits the reverse flow offluids upon the occurrence of a selected reverse fluidpressure différence across the valve.

Referring to Fig. 5 there is shown an anchoringdevice 68 arranged within a conduit 70 arranged in awellbore (not shown) and having longitudinal axis 71. Theanchoring device is radially expandable relative to theconduit 70 from a retracted mode whereby the device 68 isradially spaced from the conduit 70, to an expanded modewhereby the device 68 is radially expanded against theconduit 70. The anchoring device 68 includes acylindrical body 72 which fits longitudinally in theconduit 70 and radially déformable annular anchors 74, 76which are arranged at opposite ends of the cylindricalbody 72. A wedge-shaped annular expander ring 78 fitswithin anchor 74 and a similar wedge-shaped expanderring 80 fits within anchor 76. The expander rings 78, 80are interconnected by a plurality of circumferentiallyspaced rods 82 made of shape memory métal. Each rod 82extends through a corresponding bore 84 provided inexpander 78 and has a T-shaped head 86 at the outer end 12 117 9 8 of the bore 84, and is connected to expander 80 by ascrew connection 88. The contact surface between theexpander ring 78 and the anchor 74, and the contactsurface between the expander ring 80 and the anchor 76are serrated so as to lock the expander rings 78, 80 tothe respective anchors 74, 76 upon inward axial movementof the expander rings 78, 80. The rods 82 aretransformable from an extended shape below a selectedtransition température to an retracted shape above theselected température. In the extended shape of the rods82, the expander rings 78, 80 are at an initial axialdistance whereby the anchors 74, 76 are radially spacedfrom the inner surface of the conduit 70. Upon trans-formation of the rods 82 to the retracted shape, the rods82 axially pull the expander rings 78, 80 towards eachother thereby radially deforming the anchors 74, 76against the inner surface of the conduit 70 which therebybecome locked against the conduit 70.

During normal operation a heater is lowered in thecylindrical body 72 and operated so as to raise thetempérature of the rods 82 to the transition températurewhereupon the rods retract so as to pull the expanderrings 78, 80 towards each other and thereby radiallyexpand the anchors 74, 76 against the inner surface ofthe conduit 70. The expander rings 78, 80 become lockedto the respective anchors 74, 76 by virtue of theserrated contact surfaces. The rods 82 can expand freelythrough bores 84 when the température of the rods dropsagain below the transition température.

Referring to Figs 1-5, instead of the main wellboreand the branch wellbore producing from a single réservoirzone, these wellbores can produce from mutually spacedréservoir zones.

The above detailed description refers to a main wellbore and one branch wellbore for the sake of

Claims

-14- CLAIES 117 9 8 !.. A. System, including . a. conduit, having a longitudinal· axis.,., anda device which is radially expandable relative to the conduit from a. retracted. mode, whereby the . device. is radially spaced from. theconduit, to an expanded mode wherehy the device is radiallyexpanded against.. the. conduit, wherein the. device. include.s a shapememory métal element transformable from a first shape to a secondshap.e.. upon reaching. a seiected. température, the... shape. memory métalelement being arranged to expand the device from the retractedmode.. tQ the. expanded.. mode., upon. transformation, of. the.. memory. mptalelement from the first shape to the second shape, wherein theconduit is... an. outer. conduit. and. the system further. comprises, apinner conduit extending.coaxially into the outer conduit wherebyan., annular. s.pac.e. is defined between the. outer.. conduit, and theinner conduit, characterized in that the device is capable of b. eing moved. into o.r ont of. said annular. space...
2. The System of claim 1, wherein the expandable device forms asealin.g device. arranged in said annular. space,. which s.ealingdevice in the radially expanded mode thereof is expanded againstsaid inner conduit, and. against. said outer conduit.
3. The system of claim 2, further including a branched wellboreSystem formed in ..an. earth formation, the branched. wellbore. systemcomprising a main wellbore provided with a main casing, a branchwellbore provided... with a branch. casing,. and., a., casing.. junctionmember having a main bore and a branch bore in fluid communicationwith. the main, bore, the main bore, being. an. extension, of.. the. mpin,casing, the branch bore being an extension of the branch casing,and. wherein said. inner conduit, is. formed by the branch. casing,andthe outer conduit is formed by the branch bore. - 15 - ί 7 9 8 <
4. The System of claim 3, wherein the earth formationincludes a hydrocarbon fluid réservoir zone, anoverburden layer located above the réservoir zone and acap rock layer located between the réservoir zone and theoverburden layer, and wherein the casing junction memberis located in the overburden layer.
5. The System of claim 3 or 4, further including asecondary conduit extending through said main casing andinto said branch bore in a sealing relationship with thebranch bore.
6. The System of claim 5, wherein the secondary conduitis one of a hydrocarbon fluid production conduit and aservice conduit into which a wellbore tool for performingan operation in the branch wellbore extends.
7. The System of claim 6, wherein the secondary conduitis a service conduit through which a drill string extendsso as to further drill the branch wellbore.
8. The System of any one of daims 2-7, wherein thesealing device in the retracted mode thereof is radiallyspaced from the outer conduit and from the inner conduit.
9. The system of any one of daims 2-8, further including a centralising device arranged in the annularspace for centralising the inner conduit within the outerconduit.
10. The System of claim 9, wherein the centralisingdevice is radially expandable from a retracted mode inwhich the centralising device is radially spaced from atleast one of the outer and inner conduits, and anexpanded mode in which the centralising device isradially expanded against the inner conduit and againstthe outer conduit so as to centralise the inner conduitwithin the outer conduit, the centralising deviceincluding a secondary shape memory métal elementtransformable from a third shape to a fourth shape uponreaching a selected transition température and being - 16 - ‘117 0 · arranged to expand the centralising device from theretracted mode to the expanded mode thereof upontransformation from the third to the fourth shape.
11. The System of any one of daims 2-10, wherein thesealing device in the expanded mode thereof provides ametal-to-metal seal between the inner conduit and theouter conduit.
12. The System of any one of daims 1-11, wherein thedevice includes a wedge shaped expander being arranged toradially expand the device upon a selected axial movementof the expander, and wherein the memory métal element isarranged to induce said selected axial movement to theexpander upon transformation of the memory métal elementfrom the first shape to the second shape thereof.
13. The System of daim 1, wherein the device is ananchoring device arranged within the conduit and adaptedto be anchored to the inner surface of the conduit whenin the radially expanded mode.
14. The System of daims 13, wherein said conduit formspart of a wellbore System formed in an earth formation.
15. The System substantially as described hereinbeforewith reference to the drawings.