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CA1181000A - Insulating tubular conduit apparatus and method - Google Patents

Insulating tubular conduit apparatus and method

Info

Publication number
CA1181000A
CA1181000A CA000403092A CA403092A CA1181000A CA 1181000 A CA1181000 A CA 1181000A CA 000403092 A CA000403092 A CA 000403092A CA 403092 A CA403092 A CA 403092A CA 1181000 A CA1181000 A CA 1181000A
Authority
CA
Canada
Prior art keywords
tubular member
flared
wall thickness
inner tubular
tubing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000403092A
Other languages
French (fr)
Inventor
David M. Mcstravick
John R. Baker
David V. Chenoweth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Baker International Corp
Original Assignee
Baker International Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US06/272,411 external-priority patent/US4396211A/en
Application filed by Baker International Corp filed Critical Baker International Corp
Application granted granted Critical
Publication of CA1181000A publication Critical patent/CA1181000A/en
Expired legal-status Critical Current

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16LPIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L59/00Thermal insulation in general
    • F16L59/14Arrangements for the insulation of pipes or pipe systems
    • F16L59/15Arrangements for the insulation of pipes or pipe systems for underground pipes
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • EFIXED CONSTRUCTIONS
    • E21EARTH OR ROCK DRILLING; MINING
    • E21BEARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B36/00Heating, cooling or insulating arrangements for boreholes or wells, e.g. for use in permafrost zones
    • E21B36/003Insulating arrangements

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Thermal Insulation (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE

A concentric insulating tubular conduit member for use in forming a conduit string, such as a tubing string in a subter-ranean well, is disclosed. Each individual concentric conduit comprises an outer tubing and an outwardly flared inner tubing welded to the outer tubing at the end of the flared section. The inner tubing member is formed from an initially straight cylin-drical member having enlarged ends and, when outwardly flared, the flared ends, although stretched, have a thickness at least equal to the nominal thickness of the inner tubular member.
Insulation may be contained within the annular cavity between the inner and outer tubing members and between inner and outer coupling members at the juncture between adjacent tubing sections.

Description

1 ! BACKGROUND OF THE INVE~ION
- -- .
! 1. FIELD OF TH~ INVE~TION: This invention generally ~relates to an insulated conduit having particular utility in subterranean wells and more particularly to a concentric walled insulated conduit having an annular space between the walls within which an insulating material is deposited and sealed ! therein.
,l 2. DESCRIPTION OF THE PRIOR ART: In producing some subter-_ _ _ ,'ranean wells, steam is injected into an injection well to increase 'recovery of hydrocarbons by reducing high viscosity crude oil, ! otherwise know,n as "heavy crude". The lower viscosity makes the oil more readily pumpable. One ~echnique for doing this is to inject a high quantity of steam into the production zone contain-¦¦ing "heavy crude" for an extended period of time, such as from ,labout three to about five weeks. At that point, the viscosity of ,l ~he heated crude will be reduced and will be readily pumpable,I through a production well in communication with the produe~ion 'i zone. The injection well may also be modified for production. A ;
I steam 'Iflood" may also be provided by known techniques, generally ~ ; through an injection well, to drive the flood and the produced hydrocarbons into a nearby production well.
! One of the major problems in injecting steam into a subter-ranean production zone through conventional well production 1! tubing is that the steam loses a large quantity of its heat to ~I the ~ell bore casing and surrounding formation as i~ travels ! downwardly to the production zone. Attempts have been made in i the past to reduee the heat loss of steam introduced into sub-.¦ terranean formations. One such attempt is disclosed in U. S.
¦¦ Patent Mo. 3,511,282, issued on May 12, 1970. This paten~
J discloses a dual-wall tube structure ha~ing insulation sealed in , -2- ~

he annulus between the inner and outer walls by bushings respec^
i tively welded at each end between the inner wall and the outer wall. The inner wall is prestressed in tension prior to being li welded to the outer wall. The space defined between the inner 'I and outer walls is filled with a conventional in~ulating material, ! such as calcium silicate. Althou~h this technique mav be satis-~i! factory in some oil field installa~ions, it is not satisfactory Il for all oil field installations where large temperature differen-11 tials are encountered between the inner and outer wal]s. In this ~I case, even though the inner wall is prestressed in tension, the inner wall, as it is heated, will elDn~ate with respect to the outer wall so that the inner wall may even change from a tensi~n l! to a compression condi~ion with the attendant danger of buckling.
¦~ The magnitudes of the rorces generated are such that localized i5 !¦ s~res~es are created in the weld areas causing cracks which permit exposure of the insulation to well fluids and eventually causing failure or degradation of the insulating s~ructure.
!I Centralizers are incorporated to reduce buckling~ but may also, Il in turn, contribute to a loss of heat because of the generally 1 durable nature of such devices.
Another known technique of handling the aforedescribed temperature differential and resulting elongation between the inner and outer walls of an insulating tube is to place a thin walled bellows betT~een the two walls a~ each end of the assembly, ~5 one end of each of the bellows being rigidly attached to the il inner wall, and the other end of the bellows being rigidly ¦ at~ached to the outer wall. This technique, of course, relieves the strain on the welds and joining structure between ~he walls ! due ~o the relative movement between the inner and outer walls.
However, the bellows introduce other problems; namely, the bel-¦¦ lows are comparatively thin walled and delicate, being ~ypically 1, .. 'I

~ 8 ~

formed from a heat resistant, springy material, which cannot withstand the rough handling normally encountered in the oil patch.
Also known is a concentric walled thermal insulating conduit which comprises concentric tubular members in which the inner tubular member is corrugated and has flared ends welded to the outer tubular member adjacent each end. Insul-ation is provided within the annular area between the -~wo tubular members for reducing heat loss during steam injection.

1~ SUMMARY OF THE INVENTION
A concentric walled insulating tubular conduit for forming a tubular string in a subterranean well has an inner tubing member with flared endsO The flared ends of the tubing, with a thic~-ness at least equal to the nominal thickness of the inner tubing intermediate the ends, is welded to the outer tubing. Only two welds per individual conduit are necessary. The flared inner ends are fabricated by forging the ends of a tubular member having upset or enlarged ends. Although the thickness of the ends will be reduced by the forging operation, the flared ends will remain relatively ~hick, thus adding to ~he integrity of the weld. The inner tubing member is preferably prPstressed in tension relative to the outer tubular member.
An exterior coupling joins adjacent members by oonventional threaded engagement with the outer tubing and an inner coupling member extends between flared sections of the inner tubing ends.
Insulation may be incorporated between the interior and exterior li :

1 ,coupling and in the annular cavity between the inner and outer ~,ltubing. Blanket insulation, rigid load-bearing insu~ating ,l~embers, and a shield having a low thermal emmissivity are pro-i! v~ded in the axially extending cavlty.
The concen~ric walled conduit is preferably fabricated by using standard tubular members used in oil and gas wells, the Ij inner tubing originally having upset ends. Fabrication utilizing ~lthese standard tubular members yields a concentric walled tubular limember in which only L~O welds would be necessary on each conduit 0 ¦Isection for joining the flared end sections of at least nominal I tubing thickness to the outer tubing. These flared end sections, ¦ however, remain relatively long and thin, thus reducing the path ! available for conductive heat transfer.
I . , ¦ BRIEF DESCRIPTION OF THE DRAWINGS
¦ Fig. 1 is a schematic illustrating the in~ection of steam through a tubing string formed of individual conduit members Il constructed in accordance with this invention.
,¦ Fig. 2 shows two conduits coupled at ~heir ends and this ¦I section view depicts the components of the preferred embodiment of this invention.
Fig. 3 illustrates the forging operation in which a conven-I tional upset tubular is 1ared by use of a swage to form theinner tubing of the concentric insulating member.
Fig. 4 shows the profile of an upset tubular after the ends l have been flared for use as the inner conduit of the concentric l¦ walled tubular assembly.
Fig. 5 depicts the means of forming a vacuu~ within the annular insulating cavity in this invention.
Fig. 6 is a view of an alternate embodiment.

DESCRIPTIO~ OF THE PRE~L~ Y~_DlMFNT
Fig. 1 illustrates, in sche~atic form, the use ~f a plurali~y of seccions comprising ~oncen~ric walled insulating tubing members ormed in accordanee with this invention, t~ cons~ruc~ an insula-5 ting tubing string. The tubing st;lng T, sho~l in Fig. 1, per~itsthe injection of steam at the surface of the well through the ` tubing to the formation therebelow. The ins~lating tubing string " ensures that the heat loss between the surface and the forma~ion Il will not be so excessive as to defeat the function of steam 3~ il injection. The tubing string ~, comprising a plurality of individual insulating tubing conduits 2, is positioned within the well and within the well casing C in much the same ~anner as a conventional tubing string.
Il Fig. 2 shows the components of each individual conduit and ,, the interconnec~ion betwee~ adjacent abu~ting tubular conduits.
' It will be understood ~hat the opposite ends of each individual i conduit i5 of generally the same configuration as is shown in Fig. 2. Eaeh individual concen~ric insulating ~ember 2 comprises ~ an outer tubing 4 and an inner tubing 6. The outer tubing 2 1 comprises astraight cylindrical member having conventional 1 threads lO a~ each end. A conventional external coupling 8, " engaging threads lO, can be used to join adjacent concentric ! members. In order to reduce the number of welds needed to secure ,1 inner tubing 6 ~o outer tubing 4, ~he end of inner tubirlg 6 is ,, outwardly flared, as shown in Fig. ~. A single circular face !i weld 30 can then be made between inner tubular 6 and outer ! tubular 4. The refonming of inner tubing 6 results in flared ends having substantially three sections, First ou~er section 32 i generally comprises a radiused portion having an efec~ive radius ' 3D I of cur~ature approximately e~ual to or on the order of ~he ,1 .
,j .

,' separation between the inner and outer tubing. The radius of ! curva~ure need not be limited ~o this separation distance, but a ,, desirable structure can be constructed by e~loying a radius of i' curvature of that order of magnitude. As shown in Fig. 2, the l! i S l thickness of this radiused portion would be generally equal to a value, D3. Adjacent the outer radiused section 32 on each end of i' inner tubing 6, is a tapered section 34. The degree of taper in Il this section need not be large and, in the preferred embodiment Il ;
Il of this invention, a radially outward taper of 1 is employed in section 34. In the preferred em~odiment of this invention, a I¦ second more significantly tapered section 36 is employed to form ¦i, a transition between the 1 tapered section 34 and the central i! portion of the inner tubing 6. This ~ransition section 36, in ¦~ the prefPrred embodimen~ of ~his inven~ion, has a taper equal to ~5 il approximately 5 .
In the assembled configuration of a single insulating tubing ¦I conduit, as shown in Fig. 2, an annular cavity 13 is formed Il between outer tubing 4 and inner tubing 6. This annular cavity Il 13 may be filled wi~h thermal insulation. In the preferred 1! embodiment of this invention, this thermal insulation comprises a combination of a blanket insulation 12 having ceramic fibers, at ,l least one rigid insulating member 14, and a re1ective heat ¦¦ shield 18. At least one rigid cylindrical insulating member 14 !l 1 is located within annular cavity 13 between the welded ends 1! joining outer tubing 4 to inner tubing 6. In the preferred embodiment of this invention, this rigid insula~ing me~ber comprises a molded, high temperature pipe and block insulating ¦ composed by hydrous calcium silicate. This molded calcium !¦ silica~e m~mber 14 provides structural support between inner 1I tubing member 6 and outer tubing ~ember 4 between the ends of ll 8 ~

;~ annular cavity 13. In the preferred embodiment of this invention, insulating member 14 omprises a conventional pipe and block insul~ting member which is commercially available. One molded Il calcium silicate pipe and block insulation mem~er that can be 1~ used in this invention is manufactured by Johns-Manville and is co~monly reffered to under the trademark "Thermo-12". These standar~ pipe and block insulation members are available in half- ;
!j sections which can be positioned in surrounding relationship with ' I¦ respect to inner tubing 6. Metal bands 16 can then be attached ,¦ around the peripher~ of the t~o half-sections to form a single j annular insulating me~ber structurally supporting the outer tubin~ 4 relative to the inner tubing 6.
¦¦ The remalnder o annular cavity 13 contains a blanket i insulation 12, which is also commercially available. Thermal 5 ¦1 insulating blankets, composed of long mechanically bonded refrac- i Il tory fibers pr~viding a co~bination of high blankPt strength, ¦¦ flexibility and high thermal performance, are commercially i! available. In the preferred embodiment ~f this invention, a ~¦ thermal insulating blanket of the type manufactured by Johns-20 1l Manville under the trade~arks "Thermo-Mat'i or l'Ceratex", has been j employed to form a convective insulating barrier within annular cavity 13. This insulating blanket can be secured to the inner 1 tubing between calcium silicate insulating members 14 and the ¦¦ ends of annular cavity 13~ This insulating blanket 1~ can be secured to inner tubing ~ by wrapping a conventional glass fiber i tape aro~nd the exterior of the insulating blanket 14. When ¦¦ employed in ~ombination, blanket insulation 12 and the rigid ¦ calcium silicate insulating member 14 should substantially fill ¦ annular cavity 13 between ~he inner and outer tubings. In the j preferred embodiment of this invention, at least a partial vacuum (--is established in annular cavity 13 to prevent moisture from de~rading t~e performance of the convective insulation.
In addition to the convective insulating barriers provided by blanket insulation 12 and rigid insulatin~ member 14, a ,~ radiant reflective heat shield member 18 can be provided. In the preferred embodiment of this invention, this reflective heat shield is incorporated on the outer surface of inner tubing 6, and comprises a material having a relatively low thermal emis-1 sivity. In this embodiment, aluminum foil has been applied 1~ 1 around inner tubing 6. This aluminum foil comprises a reflective ! surface which will further reduce the heat transfer of this ! tubing assembly.
Annular cavity 13 provides sufficient space to contain Il insulation for maintaining appropriate heat transfer character-lj , istics over most of the length of this tubing. There does, j however~ remain a space between interior flared ends on adjacent ' tubing mem~ers. An interior coupling or cylindrical spacer member 20 can be employed to completely isolate the area other-I wise bounded by the flared inner tubing ends of adjacent conduits . and the outer coupling 8. This interior coupling 20 comprises acylindrical member having outer sections 24 and 26 having a , thickness which is less than the thickness of the central section 28 of the interior coupling member. As shown in Fig. 2, the ends ,1 24 and 26 can be wedged into engagement with the tapered section 34 of each inner tubing member 6. Insulation can then be posi-I tione~ around the exterior of interior coupling 20 to reduce heat ', loss in the vicinity o the coupling. In the preferred embodi-ment of this invention, blanket insulation of the same type as ! blanket insulation 12 used within annular cavity 13 can be : affixed around interior coupling central section 28 in a donut il .
..1 ; _g_ .

1 fashion~ The blan~et insulation ~hen fills the cavity bounded by the radiused ends of adjacent interior tubing members and the interior and exterior coupling members. An assembled tubing string or conduit comprising a plurality of individual insulating tubing conduits 2 would then have insulating material positioned within the annular space between inner tubing 6 and outer tubing 4 along substantially the entire length of the insulating tubing conduit 2. Finally, a second low emissivity barrier or radiant heat shield is provided on the exterior of the outer tubing. The ~0 outer tubiny can be painted along its entire length to provide this barxier. Two low emissivity barriers will then act to reduce heat transfer over most of the tubing.
The flared ends of inner tubing 6 not only provide an effective means of increasing the performance of ~he welds, both by reducing their number and by increa~ing the welded area, but they should also provide for low heat loss by means of conduction through the welded joint. The only heat conductivity path between the junction of the interior coupling 20 and the tapered portion 34 of inner tubing 6 is along the relatively long thin flared tubing itselP. No relatively wide bushing rnember with its inherently greater hea' conductivity is necessary. Still, the flared portion of the tubing is thick enough to provide a weld of high integrity.
The alternate embodiment of Fig. 6 employs a corrugated inner tubular member 72 with a wall thickness on the same order as conventional well tubing of the same diameter, thus proYiding a structurally rugged element but having axial springness. It is seen that the ends of the inner tubular member 72 are respectively provided with straight portions 74 and 74' and flared portions 76 and 75' with the end of each flared portion 76 and 76' being OO
1 ¦ respectively ~ecured to ~he inner surface of the outer tubular I member 80 b~ welds 78 and 78'. Also, it will be noted that the ¦ flared portions 76 and ~6' define the annular space 84 in this embodiment of the invention for receiving the insulation 86. In 3 this case, the straight portions 74 and 74' conveniently provide transi~ion surfaces between the flared ends and the corrugated portions of the corrugated inner -tubular member 11. It should be noted that the flared portions 76 and 76' are radially spaced from the corrugations on inner tubular member 72. In order to preven-t ~¦ heat loss it is essential that the corrugations, whether sinusoida or helical, not come into contact with the outer tubular member.
As with the other embodiments, the "flared portions" 76 and 76', located only a~ the ends of inner tubular member 72, are provided l to establish contact with the outer tubular member 80 while at 1~ ¦ ~he same time reducing the number of welds.

l FABRICATION
l ..
One very significant feature of the preferred embodiment of l this invention is that it can be fabricated using only conven-tional and commercially available components. While the concen tric conduit 2 can be fabricated by using a wide variety of cylindrical members, the preferred embodiment of this invention ~s!

-lOa-; ~ ~8 ~
I `can be fabricated by using standard American Petroleum Institute tubulars. In one size, this invention may utilize a standard ,12-318ths inch O.D. A.P.I. J-55 tubing havin~ ùpset or enlarged ,¦ends to allow fabrication of the flared inner ~ubing 6. In ~he ~5 '~same configuration, a 4-1/2 inch A.P.I. J-55 casing h2ving non-llupset ends can be employed for outer tubing 4. The standard !i tubîng shown in Fig. 3, such as 2-3/8ths inch O.D. J-55 tubing ¦Ihas a nominal thickness Dl along most of the tubing. This ¦Inominal thickness Dl is less than the thickness D2 of the upset ¦¦ends. The ends of the standard J-55 tubing can be flared to !!their final configuration by utilizing a forging operation ¦¦employing a swage 42, shown in Fig. 3. The swage has a beveled l¦portion 44 at its end. Adjacent this beveled entry surface 44 is ¦!a cylindrical or guide portion 46 which serves to align the ~5 ¦itubing during the forging operation. A swage transition profile jl48, havin~ a radially outward taper extends from the lower end of guide section 46. This transition profile constitutes a mirror i~age of the transition section 36 of the fabricated inner tubing ,! member 6. In the preferred embodiment of -this invention, the 20 il taper of this transition section would be on the order of 5.
Adjacent the transition section 48 is a swage taper~d profile 50 which corresponds to the tapered section 34 of the fabricated inner tubing 6. Tapered proile 50 has a ~aper which is less than the taper of transition profile 48, and in the preferred ¦ embodiment this swage profile has a taper of approximately 1 to match the ~aper of the transition section 34. At the lower end of the swage is a radiused profile 52. As with profile sections 48 and 50, the radiused profile 52 is intended to match the cooperating section on the final inner tubing member 6. Radiused I section 32 of inner tubing 6 will be formed as the outer end o a l l I ,IstandaTd upse~ J-55 tubing is forged by radiused profile 52. It " should be understood that although profile 52 is herein referred to as a radiused profile, it need not be generated by a constant llradius of curvature. The term "radiused profile" is merely l intended to indicate t~at the outward flaring of tapered section ~136 generated by profile 52 is significantly greater ~han that of adjacent sections 32 and 34 in inner tubing 6. It is believed lthat the term "radiused pro~ile" is appropriate, howcver, since ¦the actual profile would at least closely approximate a surface having a constant radius of curvature. Since the principal ¦Ipurpose o~ this radiused section is to provide radially ~raverse ¦the separation between inner tubing 6 and outer tubing 4, an ¦¦effecti~e radius of curva~ure on the order of magniture of the l¦spacing between outer tubing 4 and inner tubing 6 should be ~ ef~ective to for~ this profile. As can be seen in Fig. 3, the final shape of inner tubing 6 can be fabricated by driving swage 42 into a standard tubular 38 havlng enlarged or upset ends 40, ~Preferably, the portion of a standard tubular 38 adjacent ~he upset ends 40 would be heated prior to this forging process.
I~When the swage is driven into the end of the tubular, the tubular radially expands to form the flared end proiles desired for the ¦Ipreferred embodiment of this invention. During the course of l this forging process ~ the ends of the standard tubular 38 would 25 j not only be radially flared but they would be stretched by the ¦forging process. As the end is stretched the thickness of each ¦tubular would be reduced. The flared inner tubing 6 would have a ¦ radiused section 32 having a thickness D3, a tapered section 34 ha~ing a thickness D4, and a transition section 36 having a thickness Ds. Xf the flaring and stretching of the material of the standard tubular is confined to the upset ends 40, the 1! -12-~i ~' thicknesses, D3, D4 and D5 can be greater than or at leas~ equal I to the nominal thickness Dl of a standard tubular. Even if the i final thickness is slightly less than the nominal wall thickness ¦~ of the tubing, the use of tubing initially having upset or 1l enlarged ends should promote greater structural in~egrity in the ,l flared ends of the ~ubing. The stretching will, however, reduce the thicknesses D3, D4 and D5 to a value less than the original ¦ thickness D2 of the upset tubular ends 40. A significant advan-¦l tage to forming the inner tubing 6 from a standard tubular having ~ ¦l upset ends can be seen in that evPn though the thickness of the ¦~ standard upset ends is reduce~, the thickness D3 of radiused ¦¦ section 32 can still be larger than the nominal thickness Dl of ¦¦ ~he inner tubing member. This increased thickness should enhance the structural integrity of the welds 30A and 30B along the ~5 ,! radiused sections 32 to the outer tubular member 4. The welds ,j will extend over a larger surface area and the thickness of the !1 inner tubing adjacent the welds, including radiused section 32, ¦I tapered section 34; and transition section 36, wi 1 not be l! reduced below the nominal thickness of ~he tubing. This improved 20 li weld integrity would, in addition to the weld reliability improve-iii ment, be gained by reducing ~he number of welds at each end, After both ends OI a single inner tubing member 6 have been I 1ared by the forging process depicted in Fig. 3, the final i configuration of inner tubing 6 will be that shown in Fig. 4. At ¦ this point, the reflective heat shield or low emissi~ity barrier ~ can be applied to the outer surface of inner tubing 6. In the ¦! preferred embodiment, aluminum foil would be wrapped around the inner tubing. The rigid insulation members 14 may then be attached at appropriate positions along the exterior of the inner ! tubing by placing two half sections around the tubing with me~al 1 llbands securing the calcium silicate members to~ether. Blanket insul~tion 12 can then be attached over the remaining portion of inner tubing 6.
~i The next step in the fabrication of the final insulating 1I tubing conduit 2 would be the insertion of the inner tubing-il insulation assembly into outer tubing 4. Upon insertion, the l continuous clrcumferential surface formed at each free end of the Il flared inner tubing is positioned adjacent to the interior of Il the out~r tubing around its complete inner circumference and is ]~ 1¦ in position to be attached to the outer tubing. The radiused end I
l of inner tubing 6 can then be welded to outer tubing 4 along one end of the eoncentric tubing assembly. This first weld 30A
I extends completely around the junction between inner tubing ¦, radius section 32 and the ou~er tubing 4. Multiple passes may be il used to ensure ~hat this weld is structurally sound and completely ¦I seals the juncture between inner and outer tubing.
l In the preferred embodiment of this invention, it is desired li to prestres5 the tubing assembly by placing the nner tubing 6 in ! ~ension and the outer tubing 4 in compression. This prestress is ii Lmportant because of the loads which will be imparted to the ji conduit during high temperature operation. The outer tubing, although in compression, would serve to maintain the inner tubing ¦ member 6 substantially in its prestressed or preexpanded configura-¦¦ tion. The length of the concentric tubing assembly should there-¦¦ fore be substantially the same in both the cooled and heated ¦l configuration. In addition, the stresses in the concentric tubing assembly should be reduced during operation at elevated ~¦ temperatures. After the first weld 30A has secured one end of ¦¦ inner tubing to outer tubing, the desired prestress may be ¦1 imparted by stretching the inner tubing 6 at the opposite end of i!

1 the concentric tubing assembly. This stretchir-g operation can be ~aecomplished by mechanic211y pulling the inner tubing while holding the outer tubing fixed, or by heating the inner tubing 'rela~ive to the outer tubing. In the preferred embodiment of this invention, the inneT tubular member 6 would not be initially !prestressed beyond its yield point. After the desired amoun~ of 'prestress is imparted to the inner tubing, a second weld 30B
:extending completely around the junction between inner tubing and outer tubing is made. Again, this weld m~y consist of multiple " passes to ensure the integrity of the weld.
i Welds 30A an 30B ha~e not only secured inner tubing member 6 !lto outer tubing member 4, but have sealed ~he annular insulating cavity 13 between the inner and outer tubing. In the preferred il embodLment o this inven,ion, it is desirable to increase the '' insulating capacity of the material in annular cavity 13 by ,withdrawing the gasses in annular cavity 13 to establish a vacuum. This vacuum may be established by initially drilling a hole in, or otherwise piercing, the outer tubing 4 to form an ~opening in the annular cavity 13.
A fi~ure 54, sho~n in Fig. 5, can be used for drilling a hole into the outer tubing 6 and for evacuating the ~ases from ~annular cavity 13 This fixture comprises a clamp 56 extending l around Lhe exterior of outer tubing 6. A passage 68 extends ;ithrough fixture 54 ~adially to the outer surface of tubing 6. A
drill bushing, not shown, can be inserted into passage 68 and ' an opening or hole 60 can be drilled into the outer tubing 6 in ! alignment with radially extending passage 68. The same fix~ure . can then be used to establish at leas~ a partial vaeuum in annular cavity 13 without losing alignment ~ith the drilled hole , 60. ~he drill bushing can be removed and a plug, such as a ,. I
l! !

, -15-Itapered pin, surrounded by an annular seal 62 can be inserted , into passage 68, as shown in Fig. 5. A vacuum hos~ 58 can then be attached between fixture 54 and a vacuum pump (not shown).
! Vacuum hose 58 communicates through passage 68 to the interior 5annular cavity 13. An O-ring seal 66, between vacuum fix~ure 54 and the exterior of concentric insulating conduit 2, prevents leakage during evacua~ion of annular chamber 13. The tapered pin 64 extending into passage 68 and the circumferential seal 62 il eY.tending around t2pered pin 64 prevent leakage through passage ,~ 68 past tapered pin 64. After a suitable vacuum has been estab-' lished within annular cavity 13, tapered pin 64 may then be driven into drill hole 60 to close ~hat hole. The ou~er portion of pin 64 extending beyond the surface of outer tubing 4 c~n then Il be removed, an~, if necessary, a weld could be employed to seal ll this pin.
! After fabrication of ~he individual conduits, a plurality of ,I conduits may be assembled to form an insulated tubing strlng by i~ first inserting an internal coupling 20 in one end of each separate tubular members. The interior co.upling is wedged into the flared end of inner tubular member 6. Preferably, each interior coupling member 20 would be inserted farther into one conduit than into the adjacent conduit. If the interior coupling member 20 is wedKed into the tapered section 34 of one member , farther than into the other, the interior coupling would remain ~l affixed to a designated me~ber upon disassembly. Field disassem-1l bly could then be simplified.
i! The preferred embodiment of this invention thus comprises a il prestrPssed concentri.c tubing member having thermal insulation Il along substantially its entire length. Convective, as well as 3~ radiant insulation, is provided and the evacuation of the annular i ~J .

cavity between the two concentric tubing members re~oves residual jmoisture and reduces the heat transfer through the insulation.
The preferred embodiment -~lso employs onl~ two welds for each individual conduit. The integrity of the welds employed in this ! invention is increased bv both reducing their numbPr and by employing flared inner tubing sections in which the t~ickness of the flared ends is not reduced below the nominal thickness of the intermediate sections of the inner tubing member. Furthermore, I¦ individual concentric insulating tubing members 2 have been ll fabricated using conventional ~ubing members.
Il Although the inven~ion has been described in terms of the il specified embodiment which is set forth in detail, it should be ¦Ij understood that this is by illustration only and that the inven-!~ tion is not necessarily limited there~o, since alternative il embodiments and operating ~echniques will become apparent to ¦l ~hose skilled in the art in view of the disclosure. Accordingly, modifications are contemplated which can be made without departing Il from the spirit of the described invention.

, !
!

1~ , 11 -17- ~ '

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A concentric walled insulating tubular conduit for forming a tubular string in a subterranean well to transport a heated fluid between the surface of the well and a subterranean location while minimizing the heat loss from the heated fluid during transport, comprising: an outer tubular member;
an inner concentric tubular member having outwardly flared ends, said inner tubular member initially comprising a tubular member with enlarged upset ends with a wall thickness greater than the nominal wall thickness of the tubular member intermediate the enlarged ends, said outwardly flared ends having a wall thickness greater than the nominal wall thickness of said inner tubular member intermediate the ends thereof and less than the wall thickness of the initially upset ends; and a single circumferential weld joining each flared end of the inner tubular member directly to the outer tubular member at the flared ends with greater wall thickness, said inner tubular member being spaced from said outer tubular member intermediate the welded ends thereof to define an annular insulating cavity therebetween, said flared ends on the inner tubular member defining the ends of said annular insulating cavity, said welds forming a seal for said annular insulating cavity.
2. A concentric walled insulating tubular conduit for forming a tubular string in a subterranean well to transport a heated fluid between the surface of the well and a subterranean location while minimizing the heat loss from the heated fluid during transport, comprising: an outer tubular member;
an inner concentric tubular member having outwardly flared ends, said inner tubular member initially being in prestress tension and said outer tubular member being in prestpress compression for relieving stress resulting from transporting heated fluid, said inner tubular member initially comprising a tubular member with enlarged upset ends with a wall thickness greater than the nominal wall thickness of the tubular member intermediate the enlarged ends, said outwardly flared end having a wall thickness greater than the nominal wall thickness of said inner tubular member intermediate the ends thereof and less than the wall thickness of the initially upset ends; and a single circumferential weld joining each flared end of the inner tubular member directly to the outer tubular member at the flared ends with greater wall thickness, said inner tubular member being spaced from said outer tubular member intermediate the welded ends thereof to define an annular insulating cavity therebetween, said flared ends on the inner tubular member defining the ends of said annular insulating cavity.
3. A concentric walled insulating tubular conduit, multiple conduits being attachable to form an insulating tubular string in a subterranean well to transport a heated fluid between the surface of the well and a subterranean location while minimizing the heat loss from the heated fluid during transport, comprising: an outer tubular member; an inner concentric tubular member having outwardly flared ends, said inner tubular member and said outer tubular member initially being in prestress tension and said outer tubular member being in prestress compression for relieving stress resulting from transporting heated fluids, said inner tubular member initially comprising a tubular member with enlarged upset ends with a wall thickness greater than the nominal wall thickness of the tubular member intermediate the enlarged ends, said outwardly flared end having a wall thickness greater than the nominal wall thickness of said inner tubular member intermediate the ends thereof and less than the wall thickness of the initially upset ends, a single circumferential weld joining each flared end of the inner tubular member directly to the outer tubular member at the flared ends with greater wall thickness, said inner tubular member being spaced from said outer tubular member intermediate the welded ends thereof to define an annular insulating cavity therebetween, said flared ends on the inner tubular member defining the ends of said annular insulating cavity; exterior coupling means for attaching abutting tubular conduits; and interior coupling means for engaging said inner tubular member adjacent one of said flared ends and extending for engagement with an adjacent flared end of an abutting tubular conduit.
4. The tubular conduit of Claim 3 wherein each said flared end on said inner concentric tubular conduit comprises a radiused section.
5. The tubular conduit of Claim 4 wherein said inner concentric tubular conduit comprises a tapered section adjacent each of said radiused sections.
6. The tubular conduit of Claim 5 wherein said interior coupling means engages said tapered section.
7. The tubular conduit of Claim 6 wherein said interior coupling means engages said tapered section to form a seal therebetween.
8. The tubular conduit of Claims 3, 4 or 5 wherein said interior coupling means is wedged into said inner tubular member.
9. The tubular conduit of Claims 6 or 7 wherein said interior coupling means is wedged into said inner tubular member.
10. A concentric walled insulating tubular conduit for forming a tubular string in a subterranean well to transport a heated fluid between the surface of the well and a subterranean location while minimizing the heat loss from the heated fluid during transport, comprising: an outer tubular member;
an inner concentric tubular member having at least one outwardly flared end, said inner tubular member intitially comprising a tubular member with at least one enlarged upset end with a wall thickness greater than the nominal wall thickness of the tubular member intermediate the ends, said outwardly flared end having a wall thickness greater than the nominal wall thickness of said inner tubular member intermediate the ends thereof and less than the wall thickness of the initially upset end; welded connections at both ends of the inner tubular member to the outer tubular member with a single circumferential weld joining a flared end of the inner tubular member directly to the outer tubular member at the flared end with greater wall thickness, said inner tubular member being spaced from said outer tubular member intermediate the welded ends thereof to define an annular insulating cavity therebetween, said flared end on the inner tubular member defining one end of said annular insulating cavity, said welded connections forming a seal for said annular insulating cavity.
11. A method of fabricating a concentric walled insulating tubular conduit for transporting a heated fluid between the surface of the well and a subterranean location while minimizing the heat loss from the heated fluid during transport, comprising the steps of: flaring at least one end of a first tubular member, the one end of the first tubular member having been upset to increase the nominal thickness of the end in relation to the nominal thickness of the first tubular member intermediate the ends prior to flaring the upset end; inserting the first tubular member into a second tubular member; attaching one end of the inner tubular member to the outer tubular member; elongating the inner tubular member relative to the outer tubular member; attaching the second end of the inner tubular member to the outer tubular member, the attachment between a flared end of the inner tubular member to the outer tubular member being formed by welding the flared end to the outer tubular member, whereby the inner tubular member is prestressed in tension and the outer tubular member is prestressed in compression, with an annular insulating cavity defined, between the inner and outer tubular members, to minimize heat transfer therethrough.
12. A method of fabricating a concentric walled insulating tubular conduit for transporting a heated fluid between the surface of the well and a subterranean location while minimizing the heat loss from the heated fluid during transport, comprising the steps of: inserting a first conventional oil well tubular member having upset ends with the nominal thickness of the ends of the tubular member being greater than the nominal thickness intermediate the ends thereof into a second conventional oil well tubular member having a larger diameter; welding a first end of the inner tubular member to the outer tubular member; elongating the inner tubular member relative to the outer tubular member; and welding the second end of the outer tubular member, whereby the inner tubular member is prestressed in tension and the outer tubular member is prestressed in compression, with an annular insulating cavity defined. between the inner and outer tubular members, to minimize heat transfer therethrough.
13. The method of Claim 12 wherein the inner diameter of the outer tubular member is larger than the outer diameter of the upset ends of the inner tubular member.
14. A method of fabricating a concentric walled insulating tubular conduit for transporting a heated fluid between the surface of the well and a subterranean location while minimizing the heat loss from the heated fluid during transport, comprising the steps of: inserting a first conventional oil well tubular member having upset ends with the nominal thickness of the ends of the tubular member being greater than the nominal thickness intermediate the ends thereof into a second conventional oil well tubular member having a larger diameter; welding a first end of the inner tubular member to the outer tubular member with the weld being on the upset end of the inner tubular member; elongated the inner tubular member relative to the outer tubular member; and welding the second end of the inner tubular member to the outer tubular member with the weld being on the upset end of the inner tubular member, whereby the inner tubular member is prestressed in tension and the outer tubular member is prestressed in compression, with an annular insulating cavity defined, between the inner and outer tubular members, being sealed by the welds on the upset ends of the inner tubular member to minimize heat transfer therethrough.
15. A method of fabricating a concentric walled insulating tubular conduit for transporting a heated fluid between the surface of the well and a subterranean location while minimizing the heat loss from the heated fluid during transport, comprising the steps of: flaring the ends of a first conventional oil well tubular member having upset ends with the nominal thickness of the ends of the tubular member being greater than the nominal thickness intermediate the ends thereof to increase the outer diameter of the ends of the first tubular member; inserting the first tubular member into a second conventional oil well tubular member having an inner diameter sufficient to receive the flared ends of the first tubular member; welding a first end of the inner tubular member to the first end of the outer tubular member along the flared end of the inner tubular member, elongating the inner tubular member relative to the outer tubular member; and welding the second end of the inner tubular member to the second end of the outer tubular member along the flared end of the inner tubular member, whereby the inner tubular member is prestressed in tension and the outer tubular member is prestressed in compression, with an annular insulating cavity defined, between the inner and outer tubular member, being sealed by the welds on the flared upset ends of the inner tubular member to minimize heat transfer therethrough.
16. The method of Claim 15 wherein the flaring of the upset ends of the first tubular member is limited so that the final thickness of the enlarged upset ends is reduced during flaring but remains at least equal to the nominal thickness of the first tubular member intermediate the flared upset ends.
CA000403092A 1981-05-18 1982-05-17 Insulating tubular conduit apparatus and method Expired CA1181000A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US26472881A 1981-05-18 1981-05-18
US264,728 1981-05-18
US272,411 1981-06-10
US06/272,411 US4396211A (en) 1981-06-10 1981-06-10 Insulating tubular conduit apparatus and method

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CA1181000A true CA1181000A (en) 1985-01-15

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CA (1) CA1181000A (en)
DE (1) DE3218729C2 (en)
FR (1) FR2505973B1 (en)
GB (1) GB2099049B (en)
NL (1) NL191095C (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3318045C1 (en) * 1983-05-18 1984-12-13 BEB Gewerkschaften Brigitta und Elwerath Betriebsführungsgesellschaft mbH, 3000 Hannover Detachable, sealed screw connection for composite pipeline pieces for the transportation of heated media
US4811786A (en) * 1985-10-31 1989-03-14 Chevron Research Company Downhole gaseous liquid flow agitator
GB2346188A (en) * 1999-01-29 2000-08-02 2H Offshore Engineering Limite Concentric offset riser
DE202004008060U1 (en) * 2004-05-17 2004-07-29 Stüwa Konrad Stükerjürgen GmbH Device for evacuating a riser pipe
DE102008021201A1 (en) * 2008-04-28 2009-11-05 H. Butting Gmbh & Co. Kg Delivery pipeline system
CN101713284B (en) * 2009-11-30 2013-06-26 大庆石油学院 Over-long threaded heat pipe of sucker rod
CN102383762A (en) * 2011-11-03 2012-03-21 王凯一 Geothermal heat-insulating system and geothermal heat-insulating method for pit shaft
CZ2017562A3 (en) * 2017-09-19 2019-04-24 Dmitri Anatoljevich LEMENOVSKI Equipment for efficient drilling bitumen and crude oil and the method of preparing the drilling equipment
GB2574377A (en) 2018-05-29 2019-12-11 Acergy France SAS Sealing hollow structures

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1218895A (en) * 1914-02-10 1917-03-13 Edwin H Porter Pipe for the conveyance of fluids.
DE369398C (en) * 1920-11-07 1923-02-19 Adalbert Besta Hot gas pipeline
CH221376A (en) * 1941-04-01 1942-05-31 Sulzer Ag Double-walled pipeline consisting of individual sections for liquids or gases of high temperature.
US2419278A (en) * 1945-06-30 1947-04-22 Phillips Petroleum Co Insulated pipe
US3369826A (en) * 1961-08-22 1968-02-20 Union Carbide Corp Cryogenic fluid transfer conduit
US3511282A (en) * 1966-02-07 1970-05-12 Continental Oil Co Prestressed conduit for heated fluids
DE1904139B1 (en) * 1969-01-28 1970-12-17 Mini Petrolului Thermally insulating pipe string
FR2031746A5 (en) * 1969-02-06 1970-11-20 Mini Petrolului Heat-insulating pipe for oil explotation
NL152649B (en) * 1970-01-28 1977-03-15 Shell Int Research PIPELINE OR PIPELINE SECTION FOR THE TRANSPORT OF A FLUIDUM IN CRYOGENIC TEMPERATURES, FOR EXAMPLE LIQUID NATURAL GAS.
US3865145A (en) * 1973-05-10 1975-02-11 Foundation Cryogenic Joint Ven Pipeline system
US3885595A (en) * 1974-01-28 1975-05-27 Kaiser Aerospace & Electronics Conduit for cryogenic fluid transportation
SU777319A1 (en) * 1979-01-02 1980-11-07 Киевский Филиал Всесоюзного Научно-Исследовательского Института По Строительству Магистральных Трубопроводов Кф Внииста Миннефтегазстроя И Ан Украинской Сср Pipeline for transporting gases and liquids
DE2900528C2 (en) * 1979-01-08 1984-06-28 Halbergerhütte GmbH, 6600 Saarbrücken Pipeline to be laid in the ground for district heating systems
US4415184A (en) * 1981-04-27 1983-11-15 General Electric Company High temperature insulated casing

Also Published As

Publication number Publication date
GB2099049A (en) 1982-12-01
GB2099049B (en) 1985-02-27
DE3218729A1 (en) 1982-12-02
DE3218729C2 (en) 1994-11-17
FR2505973A1 (en) 1982-11-19
NL191095C (en) 1995-01-16
NL191095B (en) 1994-08-16
NL8202042A (en) 1982-12-16
FR2505973B1 (en) 1985-12-20

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