OA11188A - Method and device for joining oilfield tubulars. - Google Patents

Description

1 011188

METHOD AND DEVICE FOR JOINING OILFIELD TUBULARS

The invention relates to a method and device forjoining oilfield tubulars in accordance with thepreamble of claims 1 and 2.

Oilfield tubulars that are used within oil and/orgas production wells include reeled Systems, coiledtubing, expandable slotted tubing (EST), expandabletubing, accessories to well tubulars and drill pipes.Oilfield tubulars that are used outside a well areoffshore and onshore pipeline's for the transport ofcrude oil and/or natural gas, risers that extendbetween the waterbottom and a platform deck, andtethers for mooring tension leg platforms.

During drilling and completion of an oil or gasproduction or fluid or heat injection well, elongatestrings of well tubulars and accessories hâve to beinserted into the well to drill the well and protectthe well against caving in and to facilitate a safeproduction of oil and gas through the well. Theconventional way of protecting a well against caving inis to create a casing by screwing together one or morestrings of casing pipes that are lowered into the welland cemented in place. Production of oil and gas takesplace via one or more elongate production strings,consisting of production tubes that are interconnectedby screw thread couplings, which production strings aresuspended within the interior of the casing.

Accordingly the conventional procedure for drillingand completing a well requires many hundreds of screwthread connections to be made. Making up of theseconnections at the drilling floor is a time consuming 2 011188 procedure and it requires use of carefully machinedwell tubulars. A significant problem with the conventional screwthread connections is that if the wall strength at thelocation of the joint needs to be similar to that ofthe rest of the tubular the accumulated wall thicknessof the pipes at the location of the joint needs to besignificantly more than that of the rest of the pipe.

The presence of such bulbs at the locations of thejoints and the requirement that the string of tubularsmust be lowered into the well leads to the requirementof a significant spacing between the external pipewall and the internai wall of a surrounding tubularsuch as a casing or the borehole wall. For conventionalproduction tubings with male screw thread joints havinga larger outer diameter than the rest of the tubingoperational requirements normally require that theminimum spacing between the casing and nominal tubingsize is at least 2 cm at each side of the tubing wall.This requirement leads to a significant unused annularspace around the production tubing and thus to areduced production capacity of the well or an increasedwell size.

It is observed that it is known in the art to usewell tubulars with internally and externally flushscrew thread connections. A disadvantage of theseconnections is that they form weak spots with asignificantly lower strength than the rest of the pipe.

Safety requirements and explosion hazards at oil orgas wellheads limit the possibility of weldingoperations. The method and device according to thepreamble of daims 1 and 2 are known front Europeanpatent spécification 396204. It is known front this 3 011188 prior ârt reference to safely weld well tubularstogether using a friction welding technique where aring is rotated at high speed while the tubing ends arepressed onto the ring. Disadvantages of the knownfriction welding technique are, however, that it isdifficult to accurately control the température andthat the ring and pipe ends will often deform whichleads to irregular inner and outer surfaces at thelocation of the joint. The joint therefore often- has tobrought into a required regular shape by puliing anexpansion mandrel therethrough and/or by machining awayany wire-edges and other irregularities.

The présent invention aims to provide a method anddevice for joining well and other oilfield tubulars andaccessories thereof in an efficient and safe manner.

The device should be easily movable such that itcan be mounted on a drilling, workover or otheroilfield rig, such as a pipelaying vessel. The methodshould be able to be performed by drilling operatorswithout broad expertise of welding technology, whileuse can be made of existing hoisting and rig equipment.

These objects are accomplished by an amorphousbonding method and device as claimed in thecharacterizing portion of daims 1 and 2.

The method according to the invention is suitablefor joining well tubulars. In that case the methodcomprises the steps of: lowering the first tubular element into a welluntil the upper end of the element is located in asubstantially vertical orientation near the entrance ofthe well, 4 011188 hoisting the second tubular element to a sub-stantially vertical position above the first tubularelement, positioning the body of amorphous material betweenthe adjacent end surfaces of said first and secondtubular element, fixing the tubular éléments in axial alignment witheach other using the clamp mechanism and internaimandrel which is inserted into the interior of thefirst and second tubular element, placing the induction coil and seal mechanismadjacent the end surfaces to be joined, flushing the area to be joined with an inert gas,inducing the clamp means to press the end surfaces of said tubular éléments against the body of amorphousmaterial to ensure intimate contact between said endsurfaces and amorphous material, activating the induction coil to melt the amorphousmaterial and create a metallurgical bond between thetubular éléments, releasing the clamp and seal mechanisms, andlowering the interconnected tubular éléments into the well.

The substantially vertical orientation of the welltubulars during the amorphous bonding process accordingto the invention has the advantage that the upper endof the first tubular element, which is suspended in thewell, can be firmly fixed near the drilling floorwhereupon the second tubular element can be hoisted ontop of the first element by means of e.g. a crown blockof the drilling rig so that the amorphous bondingprocess can be carried out with a relatively small 5 011188 mobile bonding device which does not require a heavyfoundation frame.

In the amorphous bonding process according to theinvention the interior and exterior of the tubularéléments in the région of the amorphous ring are purgedwith inert gas. This is achieved by providing sealedchambers externally and internally that encapsulate thearea to be bonded and introducing the inert gas intothe chambers prior to initiating the heating cycle. Theinterior of the tubular éléments is sealed during thepurging/sealing process by arranging seals on a mandrelwhich is positioned inside the tubular éléments duringthe welding process which has the additional benefitthat contact between the heating éléments, heataffected zones and any flammable gases that may escapeform the well will be avoided. Preferably the mandrelis further equipped with a pair of clamps that arepositioned opposite to the external clamps on thetubing end sections so that during the bonding processthe tubular éléments are clamped between the pairs ofinternai and external clamps which allows a highcontact pressure to be exerted by the clamps to thetubular éléments without the risk of deformation orrupture of these éléments.

The présent invention also relates to a method anda device for joining oilfield tubulars for use outsidea hydrocarbon fluid production well. Examples of suchtubulars are pipelines for the transport of crude oiland/or gas, offshore risers and tethers for mooringtension leg platforms.

For oilfield tubulars that are joined in a vertical arrangement, such as tethers, risers and pipelines layed with the J-shape pipelaying technique, the 6 011188 handling and hoisting equipment is similar to theequipment used for handling well tubulars. 011188 - 7 -

For oilfield tubulars that are joined in a non-vertical arrangement the tubulars are preferably movedrnto and from the device using a ramp or rolling guideassembly.

The method and device according to the inventionare applicable to ail pipe sizes used in well and otheroilfield tubulars and can be applied to ail materialsconventionally used for well and other oilfield ·tubulars, including carbon steels, high chromium alloyssuch as 13 Cr, 22 Cr and 25 Cr, titanium and non-corrosion résistant metals.

It is observed that US pàtent spécificationNo. 5,118,028 discloses a diffusion bonding methodsolely for corrosion résistant materials that may beused in thermal and nuclear power stations and inChemical plants.

As shown in Fig. 1 of this prior art referenceshielding gas, such as nitrogen, is injected throughoutthe interior of the tubulars that are interconnected bydiffusion bonding. The absence of an internai mandreland other equipment to accurately position the tubularsin a vertical arrangement makes this known diffusionbonding method unsuitable for interconnecting welltubulars.

In the method and device according to the présentinvention the internai mandrel is essential to reducethe risk of damage to the interconnected tubularéléments by the external clamp means of the bondingdevice. It will be understood that the string of welltubulars that is suspended into the well may hâve alength of several kilométrés and that on a floating orother offshore rig the wellhead may make oscillatingmovements which require clamp means that are able to - 8 - 011188 exert extremely high clamping forces to the tubularéléments in order to properly fix the adjacent tubularends against each other during the amorphous bondingprocess. 5 These and other aspects, features, objects and advantages of the method and device according to theinvention are disclosed in the accompanying daims,abstract and drawing.

The invention will now be described in more detail 10 by way of example with reference to the accompanyingschematic drawing of an amorphous bonding deviceaccording to the invention.

Figure 1 shows an amorphous bonding deviceconsisting of a mandrel 1 and an external portion 2 15 arranged around a first and a second tubular element 3 and 4, respectively, which éléments are to beinterconnected by the amorphous bonding device to astring of well tubulars.

The external portion 2 of the device consists of a 20 set of sealing éléments 5 and 6 for use in maintaining an inert atmosphère in a thus formed external annularchamber 16 at the bonding zone, a means for introducingand removing the inert gas 7 and 8 into and from theexternal annular chamber 16, an induction heating 25 measurement and control system 9 and 10 and a set of adjustable external clamps 11 and 12 used for aligningthe tubular éléments and applying axial pressure to thebonded area. The internai mandrel 1 of the deviceconsists of a mandrel that is run into the top tubular 11 element 4 on a hydraulic line 13. The mandrel is ateach end eguipped with clamp and seal sections 14 and15. The seals and clamp sections 14 and 15 are 9 011188 hydraulically opened and closed with fluid pressurebeing supplied bÿ the hydraulic line 13. A preferred procedure for joining well tubularsusing the system shown in Figure 1 is as follows: 5 The external portion 2 of the bonding device is mounted or suspended in a substantially verticalposition above the wellhead 20 of the well in which thewell tubulars are to be inserted, for example to createa casing string or one or more production strings. 10 The tubular éléments 3,4 for use in the string or strings are stored in a slant or vertical orientationin a pipe rack near the wellhead, and the externalportion of the bonding device is located above the well(not shown) . 15 A first tubular element 3 is then retrieved from the pipe rack and lowered through the external portion2 of the bonding device into the well until the upperend of this element is located in a vertical orientation just above the lower clamp 12 of the 20 external portion 2 of the bonding device, whereupon a ring of amorphous material 16 is placed for example ontop of the first tubular element 3.

Subsequently the internai mandrel 1 of the device,w’nilst it is suspended on the hydraulic line 13 carried 25 by for example the crown block of a drilling rig mounted above the well, is lowered through the secondtubular element 4 until the mandrel 1 protrudes abouthalfway from the lower end of this element 4.

Then the mandrel 1 is clamped to the inner wall of 30 the second tubular element by activating the upper clamp/seal assembly 14 of the inner mandrel assembly 1by using hydraulic fluid energy via the hydraulicline 13, whereupon the mandrel 1, with the second 10 011188 tubular element 4 attached thereto, is hoisted to avertical position above the first tubular element 3. Asa next step the lower part of the mandrel 1 is stabbedthrough the ring of amorphous material 16 into the 5 upper end of the first tubular element 3 until the lower end of the second tubular element 4 rests uponthe amorphous material 16 on the upper end of the firsttubular element 3.

Correct orientation of the ends of the tubular10 éléments 3 and 4 is then confirmed and if necessary adjustments are made using the clamp mechanisms 12, 15and/or 11, 14 to move the éléments in relation to each other. After establishing that the abutting ends of thetubular éléments 3 and 4 are properly located in co- 15 axial orientations with the amorphous material 16 the external seal mechanism 5, 6 is activated, sealing theexternal annular chamber 17 around the area to bebonded. Inert gas is then introduced via line 13 intothe chamber 17 and within the external sealing 20 mechanism 5 and 6 and simultaneously via line 13 into an internai annular chamber 18 that is formed betweenthe internai seals 14 and 15 at the ends of themandrel 1. Following the gas purging, the lowerseal/clamp assembly 15 is activated by applying 25 hydraulic pressure via line 13 to set the clamp seal 15 against the internai wall of tubing element 3.

Subsequently a high clamping force R is applied tothe clamps 11 and 12 of the external assembly 2. As theaxial spacing between the external clamps 11 and 12 and 3C the internai clamps 14 and 15 is identical a high radial clamping force may be exerted between the clampsand the walls of the tubular éléments 3 and 4 withoutthe risk of deformation or rupture of these éléments. 11 011188

After having thus clamped the mandrel 1 andexternal portion 2 of the device to the tubularéléments 3 and 4 in such a manner that an over pressureof inert gas is présent in the external chamber 17 andinternai annular chamber 18 to ensure any access offlammable gasses from the well to the région of thebond is prevented and that a clean inert gas System isprésent around and at the bond area, axial pressure Ais applied to the clamps 11, 12 which forces thetubular éléments 2 and 3 into intimate contact with theamorphous bonding material 16.

Subsequently the amorphous bond is made byactivating the coil 9 to inductively heat the tubularéléments 2 and 3 to predetermined températures forpredetermined times whilst applying predetermined axialpressure A via the clamps 11, 12 . Lengths of heatingand cooling times together with required pressures toapply are a function of the material to be bonded andwill differ for each material. Exact températureprofiles of the materials is monitored and controlledusing control instrumentation contained in controlsystem 10.

After création of the bond a heat treatment of thebond and interconnected ends of the tubular éléments 3and 4 may be carried out carried out by furtherinductive heating and cooling as required. Pressuretesting of the bond is preferably also carried out byutilising the inert gas injection and containmentsystem provided by the annular chambers 17 and/or 18 aspreviously described. Preferably the cooling of theamorphous bond is carried out by pumping and/orrecycling inert gas through the annular chambers 17 and18. Therefore the annular chambers 17 and 18 contribute 12 011188 10 Ιο

η r\έ- '-J to creating a most versatile light weight and mobileamorphous bonding tool which is able to make andinspect an amorphous bond quickly. Typically bothannular chambers 17 and 18 will be closed and filledwith stationary inert gas during the heating step.During the subséquent cooling step inert gas will bepumped at such a speed through the chambers 17 and 18that the amorphous bond is cooled at the desired.rate.During the subséquent test phase the inert gas pressurein one of the chambers 17 or 18 is elevated to traceany inert gas leakage through any gaps between thebonded surface.

Subsequently the mandrel 1 and external portion 2of the device are released from the tubular éléments 3and 4 by releasing the internai seal/clamp assemblies14, 15 and the external seal/clamp assemblies 5, 6 and11, 12. Subsequently the bonded tubular éléments willbe lowered using the rig equipment to place themanufactured bond across an e.g. X-ray and/or ultrasonic inspection assembly at or near the wellhead 20. The bond area will be finally inspected bysaid inspection assembly to check for any flaws in thebond. A next tubular element or accessory may beconnected on top of the second tubular element 4 byrepeating the bonding process described above, whichprocess may be repeated again and again until thestring of well tubulars has its required length.

In the above described method the amorphous bondmatériel was placed on the first tubular element 3during the bonding process. An alternative would bethat an end of the first and/or second tubularelement 3 or 4 is prepared with an amorphous element 13 011188 attachëd to ît prior to placing the tubular éléments ontop of each other.

In the above described method it has been assumedthat the tubular ends hâve been prepared to tolérancessuitable for use in the bonding System. An alternativewould be to place the tubular éléments 3 and 4 in theamorphous bonding device and firmly clamp them inposition using the clamping Systems 11, 14, and 12, 15.Once in the System the ends of the tubing could beprepared using a métal milling/dressing System whichensures that the ends of the tubulars are fiat and trueby milling off a portion of the tubular éléments. Thismilling process could be carried out using millingmachinery mounted on an arm (not shown) that swingsinto position prior to the installation of themandrel 1 and external portion 2 of the bonding device.

It will be understood that instead of pumping inertgas into the internai annular chamber 18 via line 13,inert gas may also be pumped into this chamber 18 viathe external chamber 17 and the gap between theamorphous ring 16 and tubular ends before the bond ismade and before the internai sealing rings that formpart of the internai sealing and clamping System 14 and15 are activated.

It will also be understood that the method anddevice according to the invention are particularlysuitable for making up of both internally andexternally flush bonds between well and other oilfieldtubulars in a quick, safe and reliable manner.

Claims (7)

14 011188

1. A method for joining oilfield tubulars, the methodcomprising the steps of: positioning a body of welding material (16) betweenadjacent end surfaces of a pair of oilfield tubulars(3,4) that are to be joined; arranging a welding device near said end surfaces,which device is equipped with an internai mandrel (1)and external clamp (11,12), seal and inert gasinjection mechanisms (5,6,17); inducing the external clamp mechanism (11,12) topress the end surfaces against the body of weldingmaterial (16) such that the end surfaces of thetubulars (3,4) are maintained in an accurately definedaxially aligned position relative to each other; activating the external seal mechanism (5,6) tocreate a sealed external chamber (17) that surroundsthe end surfaces of the tubulars (3,4) and the body ofamorphous material (16); activating the inert gas injection mechanism (7) tofill the sealed external chamber (17) with an inertgas; heating the body of welding material such that itmelts and on cooling a metallurgical bond is createdbetween the end surfaces of the tubulars; allowing the joined tubulars to cool down;releasing the clamp and seal mechanisms; andremoving the joined tubulars from the welding device; characterized in that the welding device is anamorphous bonding device which is equipped with an 15 011188 induction heating coil, that the body of weldingmaterial is a body of amorphous material which isheated by the induction coil and that the mandrel isequipped with axially spaced seals (14,15) that areexpanded against the inner surfaces of the oilfieldtubulars to form a sealed internai annular chamberinside the tubulars which is filled with an inert gasduring the step of inducing the heating coil to meltthe amorphous material.

2. A device for joining oilfield tubulars comprising:an external clamp mechanism (11,12) and a mandrel (1) that is insertable into the interior of the tubulars (3,4), to press the end surfaces against abody of welding material (16) between the tubulars suchthat the end surfaces are maintained in an accuratelydefined axially aligned position relative to eachother; an external seal mechanism (5,6) for creating asealed external chamber (17) 'rhat surrounds the endsurfaces and the body of welding material (16); an inert gas injection mechanism (7) for fillingthe sealed external chamber (16) with inert gas; means for heating the body of welding material (16)such that it melts and on cooling a metallurgical bondis created between the end surfaces of the tubulars(3,4); and means for moving the tubulars (3,4) into and fromthe device; characterized in that the device is an amorphousbonding device which is equipped with an inductionheating coil (9) and that the mandrel (1) is equippedwith axially spaced seals (14,15) that are in useexpanded against the inner surfaces of the oilfield 16 011188 tubulars (3,4) to form a sealed internai annularchamber inside the tubulars during the amorphousbonding process.

3. The method according to claim 1, wherein theoilfield tubulars are well tubulars and the methodcomprises the steps of: lowering the first tubular element (3) into a welluntil the upper end of the element is located in asubstantially vertical orientation near the entrance(20) of the well, hoisting the second tubular element (4) to a sub-stantially vertical position above the first tubularelement, positioning the body of amorphous material (16)between the adjacent end surfaces of the first andsecond tubular element (3,4), fixing the tubular éléments (3,4) in axialalignment with each other using the external clampmechanism (11,12) and the internai mandrel (1) which isinserted into the interior of the first and secondtubular element (3,4), placing the induction coil (9) and seal mechanism(5,6,14,15) adjacent the end surfaces to be joined, flushing the area to be joined with an inert gas,inducing the external clamp mechanism (11,12) to press the end surfaces of said tubular éléments (3,4)against the body of amorphous material (16) to ensureintimate contact between said end surfaces and the bodyof amorphous material (16), activating the induction coil (9) to melt theamorphous material (16) and create a metallurgical bondbetween the tubulars éléments (3,4), 17 releasing the clamp (11,12) and seal mechanisms(5,6,14,15), and lowering the interconnected tubular éléments (3,4)into the well.

4. The method of claim 3 wherein a non-destructivemethod is used for testing of the bond, which testmethod includes pumping inert gas at elevated pressureinto a sealed annular sealing chamber (17) formedadjacent to the location of the bond and monitoringwhether any leakage of inert gas from the chamber (17)occurs.

5. The method of claim 3 wherein before and during thestep of induction heating of' the amorphous material(16) the mandrel (1) is placed inside the tubularéléments and clamped against their internai surfaces bymeans of a pair of internai clamps (14,15) that areexpanded against these surfaces at locations oppositeto the locations where a pair of external clamps(11,12) of the device are positioned.

6. The method of claim 3 wherein the second tubularelement (4) is hoisted to a position above the firsttubular element (3) by moving the mandrel (1) in adownward direction therethrough, while the mandrel (1)is secured to a hydraulic line (13), until the mandrel(1) protrudes about halfway from the lower end of thiselement (4), whereupon one of the clamps (14) isexpanded against its inner surface and the mandrel (1),while it carries the second tubular element (4), islifted by the hoisting cable (13) to a verticalposition above the first tubular element (3) whereuponthe protruding end of the mandrel is stabbed into thefirst tubular element (3) and fixed thereto after a gas 011188 purging cycle by expanding the other clamp (15) of themandrel (1).

7. The device of claim 2 wherein the mandrel (1) is atits upper end connectable to a hydraulic hoisting line(13) . 5