CA2233295C - Composite spoolable tube - Google Patents

Abstract

A spoolable composite tube (10) capable of being spooled onto a reel for storage and for use in oil field applications. The spoolable tube exhibits unique anistropic characteristics that provide improved burst and collapse pressures, increased tensile strength, compression strength, and load carryi ng capacity, while still remaining sufficiently bendable to be spooled onto a reel in an open bore configuration. The spoolable composite tube can include an inner liner (12), an interface layer, fiber composite layers, a pressure barrier layer, and an outer protective layer. The fiber composite layers can have a unique triaxial braid structure.

Description

~C:QU1.Y()~f1't!: 5t't)t)I~A13LE TUBE:
Ficld of thc~nve tier 't'Itc prwctu invctttictn rclalca ~;cncrally ttt spttulahlc luhint: ~uit.hl~
fur uw in the oil industry, and store particularly to slorc>l;thlt~ tubing cunsistiy ul'a mml,~,~iu material with the nhility lu witltatanct high atrcss.
Background ttf tl~ Inv4rt ' _n_ Spoetluhle tuhinb, that is tubing capuhh~ of being spttttlt;d upon a r~rl, iv commonly used in nunte:ruus oil well ultcralictns. 't'ypicatl oi! wll c,pvraticttts inrludc;
running wire Zinc cubic duwtt hole with well tools, working ctvt;r wells by de:livcrinp, various chemicals down bolo, attd ptt'fUt'tttlrt~; ttpt:ratlrtnS Utt the interior wrlacr of fife tlriil . hole. The tubes We:d arc: recluired to be spctul;thle ,ct that the lobe:
ells lx: used itt conjunction with cute well told then transpctrtcil ttn a reel to another well Ictc:atic»t. Wrel coiled tubing is typically capable ctf being sl>c»tled hccausc; the steel ttsvcl is tlm prtttluct e:chibits hibh ductility (i.c. the; ability to plttslically cleiurm).
Llnle,rtunumly, the re[,4atrtl ' spooling and use ml'stccl cuitd tubing causes fatigue damage that can stnldmly couae tlm steel coifed tubing to lratcturv and fail. 'The lt<t~.uulv ttfctperating ste;t:l c<,ilwl tuhinp. i.u. rill.
to personnel and high ~C:UIt()t111C VUSt resulting front dwvn time nerdrd tee rrtriwu thr broken tubing sections, fi>recs steel coiled lulling tct he rctirc:d tttler a relatively !cw num(,~r of trips into a well.
Stcul coiled luhing has also prctvcn to be suh,jcct to exlrnwicm ullr ry4at~i uses. Tube expansion rc>ults in reduced wail thickmss with the assuciatetl r~tlucti«n in thv pressure carrying cattuhiiity of the steel coiled tul,iut;. ~tcel coiled t.uhinr i.aumu is flu: art is typically liraitcd to us internal pressure up to ahctut 5,000 p,i (3~,4s5 x I toi 1';t).
Accordingly, hibhvr prewurc; and cc»ttinuuux ticxin6 typically reduces th~~
,tc:cl tuhc'x '. integrity and service liib.
IW r example. the prcst:nt ttcccptcd industry stanclard for curl c;t,iled lobo is an A-606 typo ~ mollified 11~I.~\ slcel with yield strcnpths ranging from 7t) Lsi (4H?,.i7t) Pa) to 80 ksi (551,3RU 1'a). 'fhe IlSL~A steel tutting typically undergoes bcntlity, cloria~; tl~c deployment and retrit:val uf'thc tubing, ctvcr radii si~,nitic<tntly less than fife tt~ini~nttw . bending radii needed for the tn:.tteria! to rent,iin itt 1111 elastic stata.
Th a rct,c:nc;d hrmtitt~ v,l' steel coifed tubing info anti out of plastic delirrntatit,n induces irreparable elmtr;~L,c; W fife steel tube body leading to low-cyc(t: fuligttc failure.
Aclditiunally, when steel coilrd luhin~ is exposed lu high itttrrnul I,rrssures and Rending Ictacfs, the iscUrut,ie steel is strhjwtud let high triuYial stre:a,ca i»tjxwof by tlm added Pressure and l,rtmlin~; Ictacis. -Chc high triasiul Dresses result in ,it:nilieant ttlaxtic:
deformation of thv tube anti diuntetral t;rcnvth ctf the tube body, commonly r~lerr~tl to ;ts "ballooning". When the atve;l coiled tube: cxpcrieatc:es halictuning, tire aver;tgv thrall at4~~r~c~~ ~lwi~ET

thickness of the tube is reduced, and often causes a bursting of the steel tube in the area of decreased thickness. -Steel coiled tubes also experience thinning of the tube walls due to the corrosive effect of materials used in the process of working over the well and due to materials located on the inner surface of the well bore. The thinning resulting from corrosive effects of various materials causes a decrease in the pressure and the tensile load rating of the steel coiled tubing.
It is, therefore, desirable to provide a non-steel coil tubing which is capable of being deployed and spooled under borehole conditions, which does not suffer from the limitations of steel tubing and is highly resistant to chemicals.
For the most part, prior art non-metallic tubular structures that are designed for being spooled and also for transporting fluids, are made as a hose whether or not they are called a hose. An example of such a hose is the Feucht structure in U.S.
Patent 3,856,052 which has longitudinal reinforcement in the side walls to permit a flexible hose to collapse preferentially in one plane. However, the structure is a classic hose with vulcanized polyester cord plies which are not capable of carrying compression loads or high external pressure loads. Hoses typically use an elastomer such as rubber to hold fiber together but do not use a high modulus plastic binder such as epoxy. Hoses are designed to bend and carry internal pressure but are not normally subjected to external pressure or high axial compression or tension loads.
When the ends of a hose are subjected to opposing forces, the hose is said to be under tension. The tensile stress at any particular cross-section of the hose is defined as the ratio of the force exerted on that section by opposing forces to the cross-sectional area of the hose. The stress is called a tensile stress, meaning that each portion pulls on the other.
With further reference to a hose subjected to opposing forces, the term strain refers to the relative change in dimensions or shape of the hose that is subjected to stress.
For instance, when a hose is subjected to opposing forces, a hose whose natural length is LO
will elongate to a length L 1 = LO + Delta L, where Delta L is the change in the length of the hose caused by opposing forces. The tensile strain of the hose is then defined as the ration of Delta L to L0, i.e. the ratio of the increase in length to the natural length.
The stress required to produce a given strain depends on the nature of the material under stress. The ratio of stress to strain, or the stress per unit strain, is called an elastic modulus. The larger the elastic modulus, the greater the stress needed for a given strain.
For an elastomeric type material, such as used in hoses, the elongation at break is so high (typically greater than 400 percent) and the stress-strain response so highly nonlinear; it is common practice to define a modulus corresponding to a specified elongation.. The modulus for an elastomeric material corresponding to 200 percent elongation typically' rages lorm 3UU hsi (2Uh7 x 103 Pa) tct 2UUU psi ( 13,7ti.'. x 1 t)j I'a). itt comparison, the ttlodttlus cthclaslicity life typical l,lastic matrix matcri:ll Ilaud in :1 composite tube i~ lritttt IUU,UU() psi ( 6894 x lU~t I'a) let SUU.U()() psi (;-t,~lv; 111~ I';t) hr greater, with rc~trcsutt:ttivc strains to lailuru oh I~ctm ? percent ti, I U
rrruullt. l leis Inr~;u difference in rnodulus ;end strain Ict failure hctwurn rubber and Itlastiw :utd thus hWvuutt hoses and compoaite tubua is what permits a hose tct be easily cullaltse:d tt~
al wsmttiolly flat condition under relativt:ly low cxtental peusal1ee. 'This largo dilli:rcltcv alw ulintilt;ttus the hose's capability to carry high axial tcusi<tn <tr cvmpres,ictn Ictads while tltu hi~ltur modules chaructrristic ~tt'th~ plastic matrix tnateri:tl uses! in a cctrttpositc tuba i. sullicirrttly stiff to transfer loads intc, the libcrs and thus resist higft rxlcrrtal Itressuru ;ntd :txi:tl trnsiolt sod compresyiltn withttul collage.
't'he (troccdure to citnslruct a ccnnpu,ite tube to resist light rxtcrtt:tl l,ruasuru and compressive lO:tdS IltvttIVL~ uStltb Cttfnhlvx Cctml)USItC meCllaItiea t:rtglttecrirll! I,riItc:II,IW
to ensure that tits tuhi: has su1'licient strength. (t has not been previously c<nt,icl~~rwf IS tensible to build a truly composite tuba capable ol'bving bent to a rulativrly stn;tll diutttrtur'.
rind he capable it( carrying internal Pressure and high tension and cttmltrc~sion Ictuds in combination with high exlrnal pressure re<luircrttunts. ~pecilieally :t httsu will heft amOain high compression and cxturnal prcsswre loads.
Ace~trdingly, it is one object ctf this invention to Provide aft ;tltltur:tttts ;trtd 2U method for providing a substantially non-lcrrow apctolablc tuba that dues mtt sul~l~r li'ortt the Structural limitations ofsteul tubing and that iv capable ol'hcing ci~l,lav~d amt yuctlml under bore hole conclitic>rts.
~\ further cthjcct etl'thc ittventi<tn is to Provide a cumltctaitu m~ilc<I
uthr capable of working over rolls and delivering varicttts chumic;tls ilitwn hula yuiukly and 25 inexpensively.
Altctthcr tthject ol'the invcntictn includes provtdtng ;t cttilud tuhin~;
c;ll,::hlu ofrepcated spooling anti bending without wt7cring Iirtiguc sufficient tc~
~ausr I~r;lcturiltg and titiling of the coilec! tube.
()flee objects ctl'th c invention include providing a spc,ol:thlu tuba cal,uhlu of 3U carrying corrosive fluids without causin b corrosion irt the spoolahlr tuhv. priwitlitt~; a cctiluil tube having less weight, and Prctvidin g a coiled tuba capable ctl' withat:.tncltng lugltur Inmrtt:ll pressure levels and higher external Pressure levels without loosing talc intugrily.
7'he,u and other objects will h~ aplturent froth the descriPtiult tluu litllctw,.
General De~cci~,tian, of the Invention 35 7~ltt' 1111'elltlllll attains tltu litrugoittg vhucfs by l,rovictint; :t coUttluwilu coiled tube that offers the: potential to uxcecd lh a Purlitrntunuu limitations e,f iaotntl,ic rltut;tls currently used in fonuing coiled tuhc;s, thuruhy incruaaing the servic:c lily ol'tlte cuilml Ittt,c find extending the operutictna! parameters of ttiu coiled talc. The contltosite coiled tul,u al~
the invention overcomes the tlisadvattt:t~;ta in t,r~:wnt slec:l coil tubing by prc»'idittt:. attumt;

WO 97!12166 PCT/US96115625 other things, a composite layer that exhibits unique anistropic characteristics capable of providing improved burst and collapse pressures as well as improved tensile strength, compression load strength. and load carrying capability.
The composite coiled tube of the present invention comprises a composite layer having fibers embedded in a matrix and an inner liner formed from polymeric materials. The fibers in the composite layer are oriented to resist internal and external pressure and provide low bending stiffness. The composite coiled tube offers the potential to exceed the performance limitations of isotropic metals, thereby increasing the service life of the tube and extending operational parameters. in addition, the fibers, the matrix, and the liner used in the composite coiled tube can make the tube impervious to corrosion and resistant to chemicals used in treatment of oil and gas wells or in flowlines.
The service life potential of the composite coiled tube constructed in accordance with the invention is substantially longer than that of conventional steel tube when subjected to multiple plastic defarnnation bending cycles with high internal pressures.
Composite coiled tube also provides the ability to extend the vertical and horizontal reach of existing concentric well services. In one operation, the composite coiled tube is deployed as a continuous string of small diameter tubing into a well bore to perform a specific well bore procedure. When the service is completed, the small diameter tubing is retrieved from the well bore and spooled onto a large reel for transport to and from work locations. Additional applications of coiled composite tube are for drilling wells. flowlines, as well as for servicing extended reach applications such as remedial work in wells or flowlines.
In particular, the invention provides for a composite coiled tube having an inner liner formed of polymeric materials and a composite layer enclosing the inner liner.
The composite layer contains three fibers oriented in a triaxial braid. A
triaxial braid structtue is formed of three or more fibers braided in a particular orientation and embedded in a plastic matrix. In a triaxial braid, a first structural fiber helically or axially extends along the longitudinal axis of the tube. A second braiding fiber is clockwise heiically oriented relative to the first structural fiber or relative to the longitudinal axis of the tube. A
third braiding fiber is counter-clockwise helically oriented relative to the first structural fiber or relative to the longitudinal axis of the tube, in addition, the first structural fiber is interwoven with either the second or the third or both braiding fibers. The composite coiled tube constructed with this triaxial braid structure exhibits unique anistropic characteristics having enhanced burst pressure characteristics, collapse pressure characteristics, increased 3~ bending characteristics, tensile loads, and compression loads.
The composite layer can be constructed with a matrix material having a tensile modulus of at least 100,000 psi (689.4 x 106 Pa), a maximum tensile elongation of at least 5%, and a glass transition temperature of at least 180 Degrees Fahrenheit ($2.2 degrees Celsius).
Increased tube strength can also be obtained by forming a layer having at _j_ least 80%, by fiber volume, ciF lhc fibers hclicutly oriented relative W th v lottgitttclinul axis of the tube at an angle hmwccn 30 and 70 degrees.
In :tc:cordancc with forth cr ;tepeels ctl'the invention, th c: ce>rnltosiW
lobe includes a liner that :serves us a pressure cotttainmcnl member to rcsi5t Iu:Ik:ty ul~ ilttcrn:tl fluids from within the tubing. 'f'hc inn m liner is titnned etfca-vxtrudc:d compctsim polymers. T'he polymer's fitrminl; the liner can alga include honto-polymers or co-polymers. The petl~'nteric material litrrnittg the Iinur arc impcrnteahle tct fluids li.c. t;a:;w:a and liquids). The inner lfn er can also include: ntatcrials th;tt arc ch c;micatly reaistivu tm corrosives.
The liner can be constructed to ft:tvc improved ntccltttnical hroltvrti4s that enhance the bending churaclcristics, the; strength charaetetzstics, and the pr4ssnrc;
charactet~istics of the coiled comFrosite tube. l~etr example, the liner can have: n ntoc;ftttnicvf t~ .
elongation ctf'ttt Icaat 25°ro, and a tnclt temperature of at least 2~0 degre« f':thrrnltait ( f 2 i degrees Celsius). The liner can also cnhttnce the pressure characteristics of the contpositc f5 tube by increasing the bonding strcnglh hctwcc;n the inner liner and the composite foyer.
This can be achicvc:d by placing grovcson the exterior surf'acc of the liuur, su4h ltrtt the grooves can hold at<urix material that hinds the; contpoaitc layer to the cxtvrictr c>I~ tlw liner.
Another fc;tture of flee invention includes providing a limn cnpahlv o1' dissipating static charge buildup. A liner having an additive of carbon hlark out Itrcwnt static charge buildup. !!y prc:vcnting static chur~,c buildup, the liner is nusrc lil:cly to prevent the igttitiun of tlanunahle fluid circulating within the lobe:.
In a preli:rred cnthoclitncnt, the cnntpo,itc layer is farttwl of flume cIr tttcwc Cbe:rs interwoven in a tri;txial braid ;end susprncicd in a matrix nt:tterial.
Ior lwuttplc, the composite layer can cornprisc a hrltcally extending first fiber, a aeconel tihGr c:lesrhwivc extending and h ulfutlly oriented, and a third litter counter clctcltwtse extulttlftt~ ancE
helieally orie.-nted. Tits: first. second toed tltircl liherx ore orfcntccl such that the: lirst fiber is interwoven wish citltcr the second fiber or the third fiber or both. '1'hc:
compc~situ I;tyur c:ut also include additicmal plies forntcsd of fiber ;end matrix. 'the fibers in the :ulditional htics can have fibers clricntcd in many ways, including but not limited to, triaxi:tlly br:ticlintc, biaxially braiding, intct-wovcn and filament wound.
eldcfitional aspects ol'the invention provide fife a separate; inl rtalee luyr interposed between the liner and the compovitc layer. 'this ittlerface layer :tile>w, the composite coiled tube tee withstand uxtrcrnc prc:wures inside and outsid4 lhc ml~c: witlu~ut causing de6radtttion of the CUmptWItC tube. 'I'hc intrrfitce layer bonds flee c:moftmitr layer to the liner. In additic>n, flee interface layer can aLr~'c as a trtmsiliott layc;r hUwmn thc~
composite layar and the liner. fvor exantltlc. the interface layer cafe Itav~:
;t nuululus uf' elasticity bcnvecn the axial rnadulus of elasticity e~f the liner and the axi;tl nu~dulu:; W' elasticity of the contposito luyer_ thereby proviilin~ a smooth transition in tire ntodulus o1' elasticity berivcw the liner and Lhe contpusttc layer.
~r ~ ~ r ~. ~ i~ t-. >=
y i~_.l A,..~.,;ts Other aspects of the invention include a composite coiled tube having a pressure barrier layer. The pressure barrier layer can be located external to the composite layer for preventing fluids (i.e. gases or liquids) from penetrating into the composite tube.
The pressure barner layer also prevents external pressure from being directly applied to the outer surface of the inner liner, thereby preventing exterior pressure from collapsing the inner liner. The pressure barrier layer can be formed of an impermeable material such as either polymeric film (including polyester), thermoplastic, thermoset film, elastomer or metallic film. The impermeable material can be helically or circumferentially wrapped around the composite layer. In addition, the pressure barrier layer can include a fused particle coating. Preferably, the pressure barrier layer has a minimal tensile elongation of 10% and an axial modulus of elasticity of less than 750,000 psi, to aid in the enhanced bending and pressure characteristics of the composite coiled tube.
Further features of the invention provide for a composite tube having an outer protective layer external to the composite layer. The outer protective layer can provide an outer protective surface and an outer wear resistant surface. The outer protective layer can also resist impacts and abrasion. In those aspects of the invention having both a pressure barrier layer and a outer protective layer, the pressure barrier layer is typically sandwiched between the composite layer and the outer protective layer.
Additionally, energy conductors including electrical wiring or fiber optics may be formed as an integral part of the ~spoolable composite tube. Energy conductors commonly have low strain capability and thus can be damaged easily by large deformations such as those imposed by bending. These energy conductors are thus oriented in a helical direction relative to the longitudinal axis of the tube. This orientation minimizes the strain on the energy conductor when the tube bends. In another embodiment, energy conductors can be embedded in an axial or helical orientation directly into the polymeric liner.
Various embodiments of the invention exist which include one or more aspects and features of the invention described above. In one embodiment, the spoolable composite tube comprises an inner liner and an outer composite layer. In all embodiments, the tube can be designed to include or exclude an interface layer sandwiched between the inner liner and the composite layer. The interface layer increases the bonding strength between the liner and the composite layer. Other embodiments provide for a composite tube including a liner, a composite layer, and a pressure barrier. Further embodiments include a liner, a composite layer, a pressure barrier, and an external protective layer.
While in an additional embodiment, the composite tube might include only a liner, a composite layer, and a pressure barrier. The invention also contemplates a spoolable tube having a liner, an inner composite layer, a pressure barrier, and an outer composite layer surrounding the pressure barrier.

- 6a -In one aspect, the present invention provides a spoolable composite tube, said tube comprising: a substantially fluid impervious inner liner formed from polymeric or metallic material, and a first composite layer enclosing said liner and formed of fiber and matrix, said first composite layer having a first fiber extending helically and having a second clockwise extending fiber and having a third counter clockwise extending fiber, such that said first fiber is interwoven with at least one of said second fiber and said third fiber.
In another aspect, the present invention provides a spoolable composite tube for spooling onto a reel and for unspooling for deployment, said tube extending along a longitudinal axis and comprising: a substantially fluid impervious inner liner formed form polymeric or metallic material, and a first composite layer enclosing said liner, said first composite layer being formed of a matrix having a modulus of elasticity greater than 100,000 psi (689.4 x 106 Pa) and a first set of fibers having at least 80 percent, by fiber volume, of the fibers helically oriented relative to the longitudinal axis at an angle between 30 degrees and 70 degrees, wherein the tensile strain of said composite tube, formed from said liner and said composite layer, at the point of maximum tensile strain is at least 0.25 percent when spooled on the reel and wherein said composite tube substantially maintains an open bore configuration.
In another aspect, the present invention provides a spoolable composite tube for spooling onto a reel and for unspooling for deployment, said composite tube having a longitudinal axis and comprising: a tubular, substantially fluid impervious inner liner formed from polymeric or metallic material, a first composite layer enclosing said liner and formed of a helically oriented first set of fibers and of polymeric matrix having a modulus of elasticity greater than 100,000 psi (689.4 x 106 Pa), an exterior layer external to and enclosing said first composite layer, said exterior layer being either a pressure barrier layer formed of an impermeable film or an outer protective layer providing wear resistance and having an outer surface with a coefficient of friction less than the coefficient of friction of said composite layer, and wherein said liner and said composite layer and said exterior layer constitute a composite tube having a tensile strain of at least 0.25 _ 6b percent at the point of maximum tensile strain when spooled on reel and while maintaining an open bore configuration.
In another aspect, the present invention provides a spoolable composite tube extending along a longitudinal axis, said tube comprising: a substantially fluid impervious liner, a composite layer enclosing said liner, said composite layer being formed of fibers helically oriented relative to the longitudinal axis and embedded in a matrix having a modulus of elasticity greater than 689.4 x 10~' Pa (100,000 psi~, and an energy conductor helically oriented relative to the longitudinal axis, said energy conductor being embedded in said spoolable composite tube.

Brief Description of the Drawings A more complete understanding of the invention may be obtained by reference to the drawings in which:
FIGURE 1 is a side view, partially broken away, of a composite coiled tube constructed according to the invention that includes a liner and a composite layer;
FIGURE 2 is a side view of a flattened out composite layer, constructed according to the invention, that has triaxially braided fiber components and which is suitable for constructing the composite layer of the composite tube shown in FIGURE 1;
FIGURE 3 is a cross-sectional view of the composite coiled tube having an inner liner surrounded by multiple composite layers;
FIGURIJ 4 is a side view, partially broken away, of a composite coiled tube constructed according to the invention having a liner, an interface layer, and a composite layer;
FIGURE 5 is a side view, partially broken away, of a composite coiled tube constructed according to the invention having a liner, an interface layer, a composite layer, and a pressure barrier;
FIGURE 6 is a side view, partially broken away, of a composite coiled tube constructed according to the invention that includes a liner, an interface layer, a composite layer, a pressure barrier, and an outer protective layer;
FIGURE 7 is a side view, partially broken away, of a composite coiled tube constructed according to the invention that includes a liner, a composite layer, and a pressure barrier;
FIGURE 8 is a side view, partially broken away, of a composite coiled tube constructed according to the invention comprising a liner, an inner composite layer, a pressure burner, and an outer composite layer;
FIGURE 9 is a side view, partially broken away, of a composite coiled tube constructed according to the invention that includes an energy conductor; and FIGURE 10 illustrates the bending events that occur when running coiled tubing in and out of a well bore.
Detailed Description of Illustrated Embodiments Composite fibers (graphite, Kevlar, fiberglass, boron, etc.) have numerous assets including high strength, high stiffness, light-weight, etc., however.
the stress strain response of composite fibers is linear to failure and therefore non ductile.
Composite coiled tubing must therefore address the strain limitations in another manner, i.e., by providing a construction to meet the requirements with a near elastic response or with large deformations of the matrix. Such a composite arrangement must have high resistance to bending stresses and internal pressure and external pressure. It must also have high axial stiffness, high tensile and compressive strength and be resistant to shear stress. All of these properties arc combined in the composite tuhulitr nlcmhcr ctf the invention to prc,viclc a coiled tubing which cars ha hens to a radius curttpatihle with winding ctntct a reascwahle sire spool.

P.K. iVitillick in the tc:ct brtrlk cntitlucl ~iher-Ctein(ilrcu is C-ocllhpv us g materials manufacturirm .and t)esien. defines a ulinPcsite in the tbtlawin~; nimulr:r:

"Fiber-reinlilrced c:elntlutsitc mitterials cnnsist of lil,crs of high strcn~;th and nutdulus embedded in or bonded to a matrix with distinct interfaces (houndtiry) hutween thc:nt. la general, fibers arc the principal load-carrying tnc:mhcr, while the aurrrtundinl; tnairix koeps them in the desirr:d locatieln and orientation, arts as a triad transfer medium hctw r:m thcnt.

and protects them l~cim environmental ditmagcs due to elevated temperatures ctnc! huntidity, for example". 'This dr;tinition defines corttl,asitcs w used in this invcntic,n W tit tile Iit,Lr~, selected from a variety ofavttilable materials including carbon, aramirl, and glass anc) the matrix or resin selected from a variety of available ntatcrials includirlg thurnlcct resin vetch as epoxy and vinyl cstc;r ctr therntoplastic resins such as polycthCretflcrkct<mc (1'1~.1:K), polyetherketonekctonc (t'IiKK), nylcln, etc. C.'ompositc structures arc cahahir: of carrying a variety of lOFlilS tn COII7htIlatIUn Or lnCiepCIldt'.tllly, inCfudin~ t6nSlott, CCtnlprelSlrtn, I1re51ttt'C'., bending, and torsion.

1~'~h5tcr's Ninth New Collegiate Dictirlnary defines how as "a Ilcxihlc tub c for eonveyin~ fluids". f3y comparison, a lutsc; is distinctly differc,nt frcnn a crimp<itr; tuhi.

Hose products such as utnhilical lines used in suhsca applictition arc conatructca ctf higlt strength fibers such as aramid, dacron, or nylr,n laid dawn in a geodesic: patient vnt<t a substrate plastic liner tubular structure. ~\ltern utivcly, a hose may he c<tltstructurl r,f hi~th strength fibers with a low ntadulus hinder such as rubber.
In cithur casr, a Itc,su is dcaignml to carry pressure foods and to exhibit gored bending llexihility, but rt he"c: has very lintitcd ability to CatTy CUnIprCSSiVt:, tCtISIUtI aIlC1 trlrSlflfl loads or external PrCSSllrt'..

G' ' '1'!IC CUmprt5lte tube described ttl this invention csnnot r>Ilfy Carr}' 111~,'h interns! pressure hut can also carry high crlmprexwvc, tension and trlrstotl Ictillls.

independently ur in conlhinatian. Such capability is essential if the tubing is to he itsr:d fc,r applications such ascoiled tubing in which the tuhin g is pushed into a hiL~tt pressure reservoir and to UVCfCrtrtle the friction to nutvenlent witllin the: well hetrc. cvPcciully litr highly devilttCd or horizontal wells. In addition, the tube is recluirc:d to carry its ctwn wci~!ht as it is susj~r:ndcd for 2U,t)t)t) ft (6.09Gkn,) or more in a well lx,re and to hr ahlu t<t have high putting capability to extract tools or to overcarttc being struck from swat and c:ircu)ntittf;

solids which have collapsed zrc,und the tube. Such loads in the case of coilrd twhin~, itt derep welts enn lx in excess of 2Uk lbs (9()7 t kg). '1'h4 tubing must also by c:,tpcihlc of carrying high ictrsion loads. It was net considered feasible until the dmclctpnlmit represented in the current patent application, that one could design anrl hail a cotitllc,sitr tube capable of hr.ing bent to a rt:latively sntalt diameter such as rcduircd lc,r cirilr:U tu1'ttt~;

spooling and >itttultaneousiy be capable cil'carrying internal pressure ;tttd atll~:r turils.

Ah~'NO'~ s~~Fr w0 97112166 PCTNS96/156Z5 In forming composite structures, several well known techniques may be used such as pultrusion, fiber winding, braiding and molding. In pultrusion.
fibers are drawn through a resin impregnating apparatus, then through dies to provide the desired shape. Alternatively, the resin may be injected directly within the die. Heat forming and curing structures are provided in conjunction with the dies. 1n fiber winding, the various layers forming the composite structure are each formed by winding or wrapping fibers and a polymer matrix around a mandrel or some other underlying structure that provide a desired shape. Successive composite layers can then be applied to underlying composite layers. A triaxial braiding structure can be manuf~tured using the fiber winding techniques disclosed in Quigley, U.S. Patent 11o. 5,188.872 and in Quigley, U.S. Patent No.
RE 35,081.
FIGURE 1 illustrates a composite coiled tube 10 constructed of an inner liner 12 and a composite layer 14. The composite coiled tube is generally formed as a member elongated along axis 17. The coiled tube can have a variety of tubular cross-1 ~ sectional shapes, including circular, oval, rectangular, square. polygonal and the like. The illustrated tube has a substantially circular cross-section.
Liner 12 serves as a pressure containment member to resist leakage of internal fluids from within the composite coiled tube 10. In one embodiment the liner 12 is metallic, and in an alternative embodiment the line 12 is formed of polymeric materials having an axial modulus of elasticity exceeding 100,00 psi (689.4 x lOePa). A liner having a modulus exceeding 100,000 psi (689.4 x 1 O6 Pa) is preferable as it is indicative of a tube capital of carrying high axial tension that does not cause the tube to compress or break. In addition, a liner with an axial modulus of elasticity less than 500,000 psi (3445.5 x lO6Pa) advantageously allows the liner to bend, rather than pull away from the composite layer, as the composite tube is spooled or bent around a reel.
The polymeric materials making up the liner I 2 can be thermoplastic or thermoset materials, for instance the liner can be formed of homo-polymers, co-polymers, composite ~lymers, or co-extruded composite polymers. Homo-polymers refer to materials formed from a single polymer, co-polymers refers to materials formed by 30 blending two or more polymers, and composite polymers refer to materials formed of two or more discrete polymer layers that have been permanently bonded or fused.
The polymeric materials forming the inner liner are preferably selected from a group of various polymers, including but not limited to: polyvinyiidene fluoride, etylene tetrafluoroethylene, cross-linked polyethylene ("PEX"), polyethylene. and polyester. Further exemplary 35 thermoplastic polymers include materials such as polyphenylene sulfide, polyethersulfone.
polyethylene terephthalate, polyamide, polypropylene, and acetyl.
Liner 12 can also include fibers to increase the load carrying strength of the liner and the overall load carrying strength of the spoolable composite tube 10. Exemplary - I l) -composite tihers inclttdr gr;tphitc, kcvlar, liher~;lu~a, boron. and pulycatrr lihm:s. ;»ul aramid.
'i'Ice litter 12 can he fitrtnc:d to he resistive to uorrewivc t:hetnicals such as heterocyclie nmittes, irturgattic sul(itr compound, :utd nitrcyencrus ;ml ncOylenir c,r~:utie compounds. '1'hrc:e types of gin cr ntatcrial, Ixtlyvinylidene tluuridv ("I'VI)I~"I, vt) lmtc:
.ttarafluoroeth)'leuc ("E:'1'l~l:"), anti pulyethylcne ("Nl;"), have hecn lintttd tct ntc~t tlm severe chemical cxltuaure chartcteristics dcrnandcd in lrtrticular applicatic~us involving vctntltwitv coiled tubinb. 'fwu particularly attractive material:: lift the liner ;ere the !t(.' 1 t)-tlliu gradml' PVDF, manutuc;tured by Atoch cm, and'I'clicl~' ntttnulacturc:cl 1)uI'ont.
In other crnhctclirnentv at' liner 12, the litter cotttprisus ro-p«lyrncrs litrntcd tct achieve enhanced liver charactcristica, welt as cctrrosictn resistance. S~e:rr reslsl:tttuu attd electrieat resistance. 1'ctr instance, a liner 12 can he tirrrttcd etf a ltolyntrr attd act acttlitive such that the liner has a high electrical resistance or such that tltv liner cli,sip:uw ,tatic:
charge buildup within the coutpasitts tube 1 (). In particular, carh<rn hl:rck can ht ndct~:c! to :t I 5 polymeric material to litrm a liner l? having; a rcsistivity an the order eel' 1 t)x ohmsleentimcter. Accordingly, the: varhc»t black :ulditivc; f'ortns a titmr 1?
lutving an ' increased elvctrie:al c;onducaivity that provides a static discttarge c:tpahility, t Itc vatic discharge c:apahility aelvantagcuusly pt'c;vcnta the ignition ol' flammahl flrricla huin~~, circulated within the ccrmpo:;ite coiled tub v It), 2t) In a further aspect ctl'the invGntiott. the gin e;r 12 leas :.t ntechanival elc»tgation of at least 25%. A liner with a mechanical c;longaticm o1' at least 25°.a, ~:an witltst;»ul thr increased bending and stretching strains placed upon the liner a:; it is cnilcd c»ttct a rrel attd inserted into and rrntervcd f~outt various well bores. ~lccarciin~ly, the nw:lt:,ttirul elongation eharactc;ristics u('the liner prolottg t(m c>verail lice of the veanhe~site; cmilccl trrh~~
25 10. In addition, the litter 12 prc;fcrahly has a n~clt tcntperaturc of at Ira,t '_'Str' l~ahrunhe:it ,e>
r': that the liner is not alts:red ctr changed durin b the manut'acturing pruce's for licrctting the t - composite coiled tubing. A liner having lheac clrtracteristics typically Ita, a r:ulial thickness in the range al't).02 inches (t).()St)8 em) - U.25 inches ((1.635 rm).
'I'hc ccrntposite layer l~t can be titrnteci crl'a number c~l'ltlivs, eaclt ply having 3U a fibers dispctscd with a matrix, such as a polymer, resin, or therrnctplastic. 'I'hc fiber:;
typically cc»ttprise atrttctut;tt fibers and flexible yarn components. '1'h~
atructnral lihvt-s ;rte formed of ciih et carhetn, nylon, Polyester, aramid, thc:rmaplaatic, or glaa,.
'1-hc tluxil~le yarn components, or braiding lihers, arc litnmct ul'cither nylctn, Ixtlyc:,W
r. ar;atrict, thermoplastic, or glass. The fibers included in layer 14 can be woven, hraiclecl. latitted, 35 stitched, circumfercnti;tlly wound. or hclically wound. Itt particular', flee: fih~rv run he biaxially or tria:ciatly braided. 'I'hc composite; layer I-i can br tbrtnucl thruut;l t,ultrwi<m processes, braiding processes, or cuntinttuus tilantent winding prctccaws. :\
tube li>rntccl eel' the liner 12 feted tltl eUlttptrSltC layer l~ fett'ttt a cuttt(tcrsitc; tube having ;t nr;t~ciruurrr tc.~wile AE~~;EU;GEu S;-iEET

strain of at least 0.25 percent and being capable of maintaining an open bore configuration while being spooled on a reel.
The liner 12, illustrated in FIG. 1, can also include grooves 15 or channels on the exterior surface of the liner. The grooves increase the bonding strength between the liner 12 and the composite layer 14 by supplying a roughened surface for the fibers in the . composite layer 14 to latch onto. The grooves can further increase the bonding strength between the liner 12 and the composite layer 14 if the grooves are filled with a matrix. The matrix acts as a glue, causing the composite layer to be securely adhered to the underlying liner 12. Preferably, the grooves are helically oriented on the liner relative to the longitudinal axis 17.
FIGURE 2 shows a "flattened out" view of a preferred composite layer 14 having a fiber component 20 interwoven with a plurality of like or different fiber components, here shown as a clockwise helically oriented fiber component 16 and a counterclockwise helically oriented fiber component 18. The configuration of layer 14 shown in FIGURE 2, is appropriately denoted as a "triaxially braided" ply. The fiber components 16, 18, 20 are suspended in a matrix 22.
Helically oriented fibers are fibers that follow a spiral path. Typically, helical fibers spiral around a mandrel underlying the composite tube or they spiral around underlying layers of the composite tube. For example, a helically oriented fiber follows a path comparable to the grooves around the shaft of a common screw. A helical fiber can be described as having an axial vector, an angle of orientation, and a wrapping direction. The axial vector indicates that the helical fiber can follow a path along the length of the tube 10 as it spirals around the tube, as opposed to a fiber that continually wraps around a particular section of the tube 10 without extending along the length of the tube. The angle of orientation of the helical fiber indicates the helical fiber's angle relative to a defined axis, such as the longitudinal axis 17. For example, a helical fiber having an angle of 0 degrees is a fiber that extends parallel to the longitudinal axis and that does not wrap around the tube 10, while a fiber having an angle of 90 degrees circumferentially wraps around the tube 10 without extending along the length of the tube. The wrapping direction of the helical fiber is described as either clockwise or counter-clockwise wrapping around the tube 10.
The fiber components can be formed of carbon, glass, aramid (such as kevlar~ or twaron~), thermoplastic, nylon, or polyester. Preferably, fibers 16 and 18 act as braiding fibers and are formed of either nylon, polyester, aramid.
thermoplastic, or glass.
Fiber 20 acts as a structural fiber and is formed of either carbon, glass, or aramid. Fiber 20 increases the axial strength of the composite layer 14 and the spoolable tube 10.
The matrix material 22 is generally a high elongation, high strength, impact resistant polymeric material such as epoxy. Other alternative matrixes include nylon-6, vinyl ester, polyester, polyetherketone, polyphenylen sulfide, polyethylene, polypropylene, and thermoplastic urethanes.
Fiber 20 extends helically or substantially axially relative to the longitudinal axis 17. The helically oriented fiber component 16 and 18 tend to tightly bind the longitudinal fiber component 20 with the matrix material 22 in addition to providing increased bending stiffness along axis 17 and increased tortional strength around axis 17.
The helically oriented fiber components 16 and 18 can be interwoven amongst themselves.
To this end, successive crossings of two fiber components 16 and 18 have successive "over" and "under" geometries.
According to a preferred aspect of the invention, the composite layer includes a triaxial braid that comprises an axially extending fiber component 20, a clockwise extending second fiber component 16 and a counter-clockwise extending third fiber component 18, wherein the fiber 20 is interwoven with either fiber 16 or fiber 18.
Each helically oriented fiber 16, 18 can therefor be considered a braiding fiber. In certain aspects of the invention, a single braiding fiber, such as fiber 16 binds the fiber component of a given ply together by interweaving the braiding fiber 16 with itself and with the axially extending fiber 20. A fiber is interwoven with itself, for example, by successively wrapping the fiber about the member and looping the fiber with itself at each wrap.
In another aspect of the invention, axially extending structural fiber 20 is oriented relative to the longitudinal axis 17 at a first angle 28. Typically, fiber 20 is helically oriented at the first angle 28 relative to the longitudinal axis 17.
The first angle 28 can vary between 5° - 20°, relative to the axis. The first angle 28 can also vary between 30°
- 70°, relative to the axis 17. Although it is preferred to have fiber 20 oriented at an angle of 45° relative to axis 17.
The braiding fiber 16 is oriented relative to structural fiber 20 at a second angle 24, and braiding fiber 18 is oriented relative to structural fiber 20 at a third angle 26.
The angle of braiding fibers 16 and 18, relative to structural fiber 20, may be varied between +\- 10° and +\- 60°. In one aspect of the invention, fibers 16 and 18 are oriented at an angle of +\- 20° relative to fiber 20.
One failure mechanism of the composite tube during loading, especially under bending/pressure and tension and compression loading, is believed to be the development of micro-cracks in the resin and the introduction of microscopic defects between fibers. The development of some micro-cracks is also believed to be inevitable due to the severe loads placed on the tube during the manufacturing and bending of the tube. However, the effects of these micro-cracks and microscopic defects can be retarded by restraining the growth and accumulation of the micro-cracks and microscopic defects during the manufacturing and use of the composite coiled tube. The applicants have discovered that the selection of fibers 16 and 18 from the group of fibers consisting of nylon, polyester, glass and aramid mitigates and stops the growth of the microscopic defects. Thus, the selection of fibers 16 and 18 from the particularly noted materials improves the damage tolerance and fatigue life of the composite coiled tubing 10.
Applicant has further determined that the total volume of any particular fibrous material in any selected layer of the composite coiled tube affects the overall mechanical characteristics of the composite coiled tube 10, including a reduction in crack propagation. It additionally follows that the total volume of any particular fibrous material in the whole composite coiled tube also affects the mechanical characteristics of the composite coiled tube 10. A composite coiled tube having improved strength and durability characteristics is obtained by forming a composite layer 14 wherein the combined fiber volume of the clockwise extending and counter-clockwise extending braiding fibers 16 and I 8 constitute less than 20% of the total fiber volume in the composite layer 14. Further in accordance with this embodiment. the fiber volume of the axially extending fiber 20 should constitute at least 80% of the fiber volume of the composite layer 14. Preferably, the first composite layer 14 includes at least 80% by fiber volume of substantially continuous fibers oriented relative to the longitudinal axis 17 of the tube at an angle between 30-70 degrees.
When the matrix 20 is added to composite layer 14, the volume of matrix in the layer 14 typically accounts for 35% or more of the volume in the composite layer 14.
Accordingly, the combined volume of all the f hers in composite layer 14 account for less than 65% of the volume of the camposite layer 14. It is thus evident, that the volume of fibers 16 and 18 account for less than 13% of the total volume of the composite layer 14 and that the volume of fiber 20 accounts fox at least 52% of the total volume of the composite layer 14.
Matrix 20 in composite layer 14 is selected such that transverse shear strains in the laminar can be accommodated without breaching the integrity of the coil composite tube 10. The strains generally is the result of bending the spoolable composite tube over the reel. These strains do not impose significant axial stresses on the fiber, but they do impose significant stresses on the matrix 20. Accordingly, matrix 20 should be chosen such that the maximal tensile elongation is greater than or equal to 5%. The Applicant has further shown that choosing a matrix having a tensile modulus of at least 100,000 psi (689.4 x 106 Pa) adds to the ability of the coil composite tube to withstand excessive strain due to bending. In accordance with the further aspect of the invention, the matrix 20 also has a glass transition temperature of at least 180° Fahrenheit (82.2 C.) so that the characteristics of the resin are not altered during high temperature uses involving the coiled composite tube 10. The tensile modulus rating and the tensile elongation ratings are generally measured as the coil composite tube is being manufactured at 70° Fahrenheit (21.1 C). Matrix materials having these characteristics include epoxy, vinyl ester, polyester, urethanes, phenolics, thermoplastics such as nylon, polypropylene, and PEEK.

FIGURE 3 illustrates a coiled composite tube 10 having an inner liner 12 and a first composite layer 14A, a second composite layer 14B, and a third composite layer 14C. Each of the composite layers is formed of fibers embedded in a matrix, and each of the composite layers successively encompasses and surrounds the underlying composite ' layer or liner 12. At least one of the composite layers, 14A, 14B, 14C, includes a helically oriented fiber in a matrix. Preferably, at least one of the composite layers 14A, 14B, 14C, ' contains a ply as described in FIG. 2. In particular, one of the composite layers 14A, 14B, 14C, has a first helically extending fiber, a second clockwise extending fiber, and a third counterclockwise extending fiber wherein the first fiber is interwoven with at least one of the second and third fibers. The other two composite layers contain fiber suspended in a matrix. The fibers can be axially extending, circumferentially wrapped, or helically wrapped, biaxially braided or triaxially braided.
According to one aspect of the invention, the fibers in each of the composite layers are all selected from the same material. In other aspects of the invention, the fibers in each of the composite layers are all selected from the different materials.
For example, composite layer 14A can comprise a triaxially braided ply having clockwise and counter-clockwise helically oriented fibers formed of polyester and having a helically extending fiber formed of glass; composite layer 14B can comprise a ply having a circumferentially wound kevlar fiber; and composite layer 14C can comprise a triaxially braided ply having a clockwise and counter-clockwise helically oriented fibers formed of glass and having a helically extending fiber formed of carbon.
The Applicant's have discovered that additional composite layers, beyond the initial composite layer 14 of FIG. l, enhance the capabilities of the coiled composite tube. In particular, the interaction between the additional composite layers creates a synergistic effect not found in a single composite layer. The Applicant discovered that composite layers having carbon fibers carry proportionately more of the load as the strain in the coiled composite tube 10 increases, as compared to an equivalent design using glass fibers or aramid fibers. While a composite layer using kevlar (i.e. aramid) fibers provide excellent pressure/cyclical bending capabilities to the coiled composite tube 10. The kevlar fibers appear to have a weakness when compared to the carbon fibers in compressive strength. Accordingly, a coiled composite tube 10 incorporating both kevlar and carbon fibers provides a composite structure having improved characteristics not found in composite structures having composite layers formed of only carbon fibers or only kevlar fibers.
Accordingly, one aspect of the invention incorporates a composite layer 14A
formed of carbon fibers and polyester fibers in a triaxially braided structure and a second composite layer 14B formed of kevlar fibers. The kevlar fibers can be incorporated into either a conventional bi-axial braid, triaxial braid, or helical braid. For instance, the second composite layer can include two sets of aramid fibers bi-axially braided together. The coiled composite tube 10 having an inner composite layer 14A formed with carbon fibers and an exterior composite layer 14B formed with kevlar fibers provides a coiled composite tube having balanced strength in two directions and provides a coiled composite tube having a constricting force which helps restrain the local buckling of delaminated sublamina and subsequent delamination growth, thereby improving the fatigue resistance of the coiled composite tube 10. Certainly, this aspect of the invention can include a third composite layer 14C external to the second composite layer 14B. The third composite layer 14C can, for instance, include a matrix and a fiber helically oriented relative to the longitudinal axis 17.
In another aspect of the invention, as illustrated in FIGURE 3, the composite layer 14A comprises a triaxially braided ply having an axially extending fiber formed of carbon and having a clockwise extending fiber and a counter-clockwise extending fiber both formed of polyester. In addition, the helically extending fiber 20 is oriented at an 45°
angle to the axis of the coiled composite tube 10. Further in accordance with this embodiment, composite layer 14B is triaxially braided and comprises a helically extending fiber formed of carbon and oriented at an angle of 45° relative to the axis 17 of coiled composite tube 10. Composite layer 14B further includes a clockwise extending second fiber and a counter-clockwise extending third fiber formed of polyester. The third composite layer 14C, is biaxially braided, and comprises a kevlar fiber extending helically and oriented at a 54° angle to the axis 17 of the composite coiled tube 10.
FIGURE 4 illustrates a composite coiled tube elongated along an axis 17 and having an inner liner 12, an interface layer 56, and a composite layer 14.
The interface layer 56 surrounds the liner 12 and is sandwiched between the liner 12 and the composite layer 14. The interface layer 56 improves the bonding between the inner liner 12 and the composite layer 14.
It is important in the composite coiled tubing 10 that the liner 12 be integrally attached to the composite layer 14. The necessity for a bonded liner is that in certain operating conditions experienced in down hole service, the external surface of the tube will be subjected to higher pressure than the interior of the tube. If the liner is not bonded to the composite layer 14 this external pressure could force the liner to buckle and separate from the composite layer such that the liner collapses. In addition, loading and bending of the tube may introduce microscopic cracks in the composite layer 14 which could serve as microscopic conduits for the introduction of external pressure to be applied directly to the outer surface of the liner 12. Once again, these external pressures could cause the liner 12 to collapse. The interface layer 56 provides a mechanism for bonding the liner 12 to the composite layer 14 such that the liner does not collapse under high external pressures. The interface layer 56 can also reduce cracking and the propagation of cracking along the composite layer 14 and liner 12.

- l (i -In accordance with one aspect of the invention, the intrrtitcc layer S( comprises a fiber reinforced matrix where the fiber volume is Iess than -1()".v al~ tltc mUal voltune of the interface layer SG. The matrix anc! the fiber forming interfacr I:rycr qtr predominately act as an adhvsivc layer that bonds the lines 1? to the cc~mhe,situ Ivye;r 1 ~I.
The fibers within the interface layer 56 can he oriented in various ways, i»cltt~lin!' :' wnvrn or non-woven structure. Preferably, the fibers within the interface layer Sh arc pulyc~tur fibers. An interface layer buying thin structure is able to prevent the linrr I'r«rn syar:Uin~~.
from the composite layer evctt when the differential pressure between the rxteritir wad interior of the tube 10 exceeds 1,000 psi ( 6894 x 10:~ f a).
The matrix within the interlitce layer 5b can comprise: a lillccl pVyntvric layer or an unfilled polymeric layer. A tilled polymeric layer uses a pt'lymcric matrix having additives shat modify the properties ciFthc polymeric layer. 'fhc aclditivcs uaccl in the filled polymeric layer incluJe particulatcs ~tnci Fhc;rs. For instancr, rarhtm hl;tri:
powdet can he adck:d t~~ the polymeric layer m increase the conductivity ol~
the innrfacc layer 56, or chopped glass fibers can he added to the polymeric layer to inrrcusc tlic stiffness of the interlace layer 56.
According to a further embuditncnt elf the invention. the inurluc~ I:ryr It;is an axial modules df elasticity that lies between the modules ofthc elasticity ol~thu liver 12 and the modules csfelaslicity of the composite layer 14. The interfuee layer ~(~ thus Itas a modules of elasticity that transitions betw'ecn the modules of elasticity of the liner I ~ and the composite layer 14. Ejy providing a t.ranaiticmal modules of cl;L,tivity, the iO~rl'acc layer aids in preventing the liner 1'? fnim pulling away from the comhc~sit~
layrr 14 During the bending actirrn of the composite coiled tube 10.
'l~hc: interface layer SG furthermore increases the fatit;uc life ol~thv cailml composite cube l U. 'I he structure of the interface lnycr St5 achieve this by ~fissiluVinl; ahvar stress applit.~d along the length of the coiled composite tube 1(). 13y cfisaipating tlrc slmar, the interface layer nduccs cracking and the; propagation of cracks aletng the e;myocositc layer 14.
FICiUKF 5 illustrates a contpositc~ coiled tube elongatrti alcrn g :ut axis 17 and having nn iruter liner 12, an interface layer SG, a cttrnpositc luyt:r 1 a. antl a hr-~ssarc barrier layout Sfl. The pressure barrier layer 58 prevents gasc5 ur liquids ti.c. lluids) tram penetrating into the cc>tnpo5ite cailt:d tube 1 U.
It is important for two rraamls that fluids not penetrate nitu the cwapu~it~
layer 14. First, a fluid that penctrutes thniugh the tube 10 to liner 12 can build uh to a sufficient level of pressure capable of collupautg eh c liner 12. SeconJ. a lltiicl Ihat penetrates the coiled contpositt: tube 10 during exposure in the well hurl ~~~
rit~'y' c'titt:as when the coil composite tube l0 is returned to atmospheric pressure:.
Acccodingly, a coiled compusitu tube 10 can l~un~tiun rll~ctivcly witltuut a pressure harrier layer ~t; uttdcr certain cunrliticms. i'vor example. wltcn taicrc~-f'rnctutua and defects in the composite lay,cr 1 ~ do not develop to a silo that allows fluids W 1nuratsr tltu composite layer 14, a prcs:;urc barrier layer is nut ccessary.
Ilowevrr, when micrcr-fractures and passalcs through the composite layer I ~ do allows for th r mignttion r>f llids the use of a pressure barrier layer 5H is preCerrcd. r1illwtrated in t~ lCi. ~. thc pre"ru battier layer 58 generally is pvsitioneci nutsiclc: cr('th~
composite: Layer l:l.

1'he pressure harrier layer Sri can he ti~rmed of a mWtl.
Llttl'tllhpla5tlt;, thermoset films, or an elastotncr such as a whhe;r sheet.
~'1I1 these VarlUtlS lll;ttla'IalS Wlll ftutctoin as a prcsstuc httrricr because they substantially prevent. the dil~fimum ctf tiitls.

Preferable ptoperti~ of the pressure barrier layer include low pCrllleablllly t fluids (i.e., gases or liquids), high elongation, and bondability to c;umposite layer 1~. 1t is a1s referred that the pccasurc barrier layer SH have: a maximum tensile c:lungntion of t If%p ;utc!

p an axis! moduius ofclaW icily of less than 750,U()U psi (~IG825U Y lt)3 1'a). '1'h4~: values of tensile elongation and nlodulus of elasticity arc measured at 70 Hahrenhcit cturitt~ Ihc manufaeturinb of the coiled composite tube I 0. 'fhe pcrmettbility of the prcswrc harrier Layer should he less than 0.~ x 10 to the -1 () ecs per sec-c:m=-cm-cmhg.

'1'hu impermeable pressure harrier layer S8 can be iitrmucl of an inttwrmwrh~c films formed Ot~mutals or polymers. hot instttnce, acceptable polymeric films inctuclc filets formed of polyester. polyimide, polyamidc, polyvinyl fluoride, polyvinyiiclcnc lla~riJv.

polyethylene, and polypropylene, or other thermoplastiw.

'fhe impe:rmcabte film of layer 58 can he a seamlew polymer layer witieh is eoextruded or formed via a powder deposition process. Alternatively, th v imp~rmtable film can tx helically wrapped or circumfercntially wrapped around the: composite I.~ycr to fottt1 at1 overlapping anti complete barrier. 'That is.
the fiber or material ti~nnitr~; thu e barrier layer n~uat be wrapped in such a fashion that no gaps evict and the pressrrrc pressur barrier layer 58 is sealed.
f the invention provides fbr a prcasuru harrier layer 5H
t - o Another aspec having a fused pat2icle coating. A first;; particle coating is formed by grinding a pctlymuric material into a very line powder. The fine power is then heal-fused auto the c~th~:l' nuttcrittls forming the pres:;ure barrier layer SR or auto the adcrlying composite layr I.~.

FIt i(JiZC? b illustrates a composite coilrd tube clon~atcd aimb an axis 1 l and having an inner liner 12, an interface layer SO. a composite layer 14, a prvxarv h<trricr layer 58 and an outer protective layer 6t). The, interface layer SG enhances the hood betwecnthe composite: layer 1~4 to the inner liner 12. The pressure harrier layer 5tt prevents fluids from ptnctrating into the composite coiled tube:
l0. -I'he outer hrutcetivc l:rycr l'tt rovides we-ir' rc;sistance, impact resistance, and art interface layer firr the: couplitt~ lift tlw p Coiled composite tuhc 1(). The protective layer is positioned such that it sttrr<Utncls tttu pressure batTier 58.

Outer protective layer GO provides ahrwiun resistance aml vicar re:aistawe by forming an mulct surface to the coil c~,mpu~it.e tubs that has a low c~,_ct'li~:ient m( Irieaiun A,~?E!v'CE~ SHEET

thereby causing objects to slip off the coiled composite tube. In addition, the outer protective layer 60 provides a seamless Iayer for holding the inner layers of the coiled composite tube together. The outer protective layer can be formed of a filled or unfilled polymeric layer. Alternatively, the outer protective layer 60 can be formed of a fiber, such as kevlar or glass, and a matrix. The fibers of the outer protective layer 60 can be woven in a mesh or weave pattern around the inner layers of the coiled composite tube 10, or the fibers can be braided or helically braided around the inner layers of tube 10.
In either case, the fibers in the outer protective layer are wrapped helically around the inner layers of the coiled composite tube 10 in order to provide a seamless structure.
It has further been discovered by the Applicant that particles can be added to the outer protective layer to increase the wear resistance of the outer protective layer 60.
The particles used can include any of the following, individually or in combination with one another: ceramics, metallics, polymerics, silicas, or fluorinated polymers. Adding Teflon (MP 1300) particles and an aramid powder (PD-T polymer) to the matrix of the outer protective layer 60 has been found to be one effective way to reduce friction and enhance wear resistance.
In the case where the outer protective layer includes fibers, the particles added to the outer protective layer 60 are such that they consist of less than 20% by volume of the matrix. In the case where the outer protective layer does not contain fiber, a particulate such as Teflon~ MP 1300 can also be added to the polymeric protective layer.
When the outer layer 60 does not include fiber, the particles typically comprise less than 60% by coating volume of the outer wear resistant layer 60, FIGURE 7 illustrates an embodiment of the composite coiled tube elongated along an axis 17 and having a Iiner 12, a composite layer 14, and a pressure barrier 58.
FIG. 7 is similar to FIG. 5, except that it lacks the interface layer 56.
Particularly, the inner liner 12 is positioned internally to the composite layer 14, and the composite layer 14 is positioned internally to the pressure barrier 58. This figure illustrates, among other things, that the interface layer 56 can either be included or removed from all embodiments of the invention, depending upon whether the circumstances require the use of an interface layer to increase the bonding strength between the liner and the composite layer.
FIGURE 8 illustrates another embodiment of a composite coiled tube elongated along an axis 17, the composite tube includes a liner 12, a first composite layer 14, a pressure barrier 58, and a second composite layer 14'. In this embodiment, the first composite layer 14 surrounds the internal liner, and the pressure barrier surrounds the first composite layer 14. In addition, the second composite layer 14' surrounds the pressure barrier 58. Particularly, the pressure barrier is sandwiched between two composite layers 14 and 14'.
Composite layer 14' can be structured in any manner that composite layer 14 can be structured, but the layers 14 and 14' need not be identical. In addition, either composite layer 14 or composite layer 14' can include multiple composite layers as illustrated in FIG. 3. The external composite layer 14' proves useful in providing an exterior surface capable of engaging a coupling device.
The external composite layer 14' can also be fashioned to act as an outer protective layer capable of providing abrasion resistance and wear resistance.
This can be achieved by forming the external composite layer 14' from a filled or unfilled polymeric layer. The layer 14' can also achieve increased abrasion and wear resistance by helically wrapping or braiding those fibers forming composite layer 14' around the inner layers of the tube 10. Furthermore, the external composite layer 14' can be fashioned to reduce the friction of the exterior of tube 10 by adding particles to the external composite layer 14'.
The particles can include ceramics, metallics, polymerics, silicas, or fluorinated polymers.
FIGURE 9 illustrates a composite coiled tube elongated along an axis 17 wherein the composite tube includes a liner 12, a composite layer 14, and an energy conductor 60 forming part of the composite layer 14. The energy conductor provides a path for passing power, communication or control signals from the surface down through the tube to a machine attached to the end of the tube.
The energy conductor 60 can be located in either the liner, the composite layers, or the pressure barrier forming the tube 10. But is preferable to locate the energy conductors in those layers nearest the interior surface of the tube and not in those layers located near the exterior surface of the tube. If an energy conductor is located near the exterior surface of the tube it is more likely to be subjected to corrosive surfaces or materials located outside the tube 10. In addition, an energy conductor located near the interior of the tube 10 will be subjected to smaller bending strains when compared to an energy conductor located near the exterior of the tube.
An energy conductor can be embedded in any of the layers forming the tube 10 using the same methods known in the art for adding a fiber to the composite layer.
Typically, an energy conductor is wound onto a mandrel or any underlying structure while applying a matrix. Energy conductors can also be added to a fiber composite layer with a pultrusion process. For example, the energy conductor can be drawn through a resin impregnating apparatus, then through dies to provide the desired shape.
Alternatively, the conductor can be embedded in the polymer liner.
The energy conductor 60 may be an electrical or optical conductor of any material or substance capable of being modulated with information data or electrical power.
A primary concern in placing the conductor 60 in the inner areas of the composite tube 10 is to ensure that the bending strains on the conductor 60 are minimized. This is particularly critical if the conductor 60 is a fiber optic cable. Moreover, the energy conductor 60 is typically helically oriented relative to the longitudinal axis 17 of the composite tube to minimize the bending strain on conductor 60. The helical orientation allows the compression strain experienced by the section of the conductor located on the interior bend of the tube to be offset by the expansion strain experienced by the section of the conductor located on the exterior bend of the tube. That is, the conductor 60 is able to substantially distribute the opposing strains resulting from the bending action of the composite tube across the length of the conductor 60, thereby preventing irreparable damage to the conductor.
FIGURE 10 illustrates the bending cycles that a coiled composite tube 10 is subjected to when performing a typical coiled tubing service. The tubing 10 is inserted and removed from a well bore 36 located below the ground surface. A reel 42 is provided on the surface and the composite coiled tube 10 is stored on the reel 42. An injector assembly 38 is located on the surface over the well bore 36. Injector assembly 38 typically contains a roller belt 40 used to guide the coiled composite tube 10 through the injector assembly 38 into the well bore 36. The coiled composite tube 10 typically is subjected to six bending events as it is inserted and removed from the well bore 36. The first bending event 44 takes place when the coiled composite tube 10 is pulled off the service reel 42.
When the coiled IS composite tube 10 reaches the assembly 38, the coiled tube passes through two bending events 46 and 48. The bending events 50, 52 and 54 are the reverse of bending events 44, 46, 48 and occur as the coiled composite tube 10 is extracted from the well bore 36. The insertion and extraction of the tube 10 thus results in a total of six bending events for every round trip of the coiled composite tube 10. The current steel tubing being used in the field can generally be cycled three times through the bending events described in FIGURE 4 in conjunction with high internal pressures before the steel tubing fails. In comparison, the coiled composite tube of the Applicant's invention can be cycled 10,000 times through the bending events described in FIGURE 4.
It is also to be understood that the following claims are to cover all generic and specific features of the invention described herein, and all statements of the scope of the invention which, as a matter of language, might be said to fall there between.
Having described the invention, what is claimed as new and secured by Letters Patent is:

Claims (37)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A spoolable composite tube for spooling onto a reel and for unspooling for deployment, said tube extending along a longitudinal axis and comprising:
a substantially fluid imperious inner liner formed from polymeric or metallic material, and a first composite layer enclosing said liner, said first composite layer being formed of a matrix having a modulus of elasticity greater than 100,000 psi (689.4 x 10 6 Pa) and a first set of fibers having at least 80 per cent, by fiber volume, of the fibers helically oriented relative to the longitudinal axis at an angle between 30 degrees and 70 degrees, wherein the tensile strain of said composite tube, formed from said liner and said composite layer, at the point of maximum tensile strain is at least 0.25 percent when spooled on the reel and wherein said composite tube substantially maintains an open bore configuration.

2. A composite tube according to claim 1, wherein said liner is formed of polymeric materials.

3. A composite tube according to claim 2, wherein said polymeric materials forming said liner are selected from the group consisting of homo-polymers, co-polymers, and composite polymers.

4. A composite tube according to claim 1, wherein said liner further comprises ethylene tetrafluoroethylene, such that said liner is chemically resistant to corrosives selected from the group consisting of heterocyclic amines, inorganic sulfur compounds, and nitrogenous and acetylenic organic compounds.

5. A composite tube according to claim 1, further comprising an interface layer for bonding said first composite layer to said liner, such that said liner withstands separation from said composite layer at a differential pressure between the exterior and interior of said tube of at least 1,000 psi (6894 x 10 3 Pa).

6. A composite tube according to claim 1, further comprising an interface layer interposed between said liner and said composite layer, said interface layer having a modulus of elasticity between the axial modulus of elasticity of said liner and the axial modulus of elasticity of said composite layer.

7. A composite tube according to claim 1, wherein said matrix forming said first composite layer has a tensile modulus of at least 250,000 psi (1722750 x 10 3 Pa) and has a maximum tensile elongation of at least 5% and has a glass transition temperature of at least 180 Degrees Fahrenheit (82.2 degrees Celsius).

8. A composite tube according to claim 1, wherein said first set of fibers further comprises:
a set of structural fibers selected from the group consisting of aramid, carbon, and glass, and a set of braiding fibers selected from the group consisting of nylon, polyester, thermoplastic, glass, and aramid.

9. A composite tube according to claim 1, further comprising a second composite layer exterior to said first composite layer, said second composite layer being formed of a first set of aramid fibers and matrix.

10. A composite tube according to claim 1, said liner further includes at least one embedded energy conductor therein.

11. The spoolable composite tube of claim 10, wherein said energy conductor is a metal.

12. The spoolable composite tube of claim 10, wherein said energy conductor extends helically within the said liner.

13. The spoolable composite tube of claim 10, wherein said energy conductor is a light guiding medium.

14. A composite tube according to claim 1, said composite layer further includes at least one embedded energy conductor therein.

15. The spoolable composite tube of claim 14, wherein said energy conductor is a metal.

16. The spoolable composite tube of claim 14, wherein said energy conductor extends helically within the said composite layer.

17. The spoolable composite tube of claim 14, wherein said energy conductor is a light guiding medium.

18. A spoolable composite tube for spooling onto a reel and for unspooling for deployment, said composite tube having a longitudinal axis and comprising:
a tubular, substantially fluid impervious inner liner formed from polymeric or metallic material, a first composite layer enclosing said liner and formed of a helically oriented first set of fibers and of polymeric matrix having a modulus of elasticity greater than 100,000 psi (689.4 x 10 6 Pa), an exterior layer external to and enclosing said first composite layer, said exterior layer being a pressure barrier layer formed of an impermeable film, and wherein said liner and said composite layer and said exterior layer constitute a composite tube having a tensile strain of at least 0.25 percent at the point of maximum tensile strain when spooled on reel and while maintaining an open bore configuration.

19. A composite tube according to claim 18, wherein said impermeable film is helically wrapped around said composite layer.

20. A composite tube according to claim 18, wherein said impermeable film is selected from the group consisting of metallics, polyester, polyimide, polyamide, polyvinyl fluoride, polyvinylidene fluoride, polyethylene, polypropylene, and elastomers.

21. A composite tube according to claim 18, wherein said pressure barrier layer includes a fused particle coating of polymeric material.

22. A composite tube according to claim 18, wherein said pressure barrier layer has a minimum tensile elongation of at least 10% and an axial modulus of elasticity of less than 750,000 psi (5168250 x 10 3Pa).

23. A composite tube according to claim 18, wherein said liner has a radial thickness between 0.02 inches (0.0508 cm) and 0.25 inches (0.635 cm).

24. A composite tube according to claim 18, wherein said liner is metallic.

25. A composite tube according to claim 1, wherein said liner has a radial thickness between 0.02 inches (0.0508 cm) and 0.25 inches (0.635 cm).

26. A composite tube according to claim 1, wherein said liner is metallic.

27. A composite tube according to claim 1, further including an exterior layer external to and enclosing said composite layer.

28. A composite tube according to claim 27, further comprising an energy conductor embedded in one of said liner, said composite layer, or said exterior layer.

29. A composite tube according to claim 28, wherein said energy conductor is metal.

30. A composite tube according to claim 28, wherein said energy conductor extends helically along the length of said composite tube.

31. A composite tube according to claim 28, wherein said energy conductor is a light guiding medium.

32. A spoolable composite tube for spooling onto a reel and for unspooling for deployment, said composite tube having a longitudinal axis and comprising:
a tubular, substantially fluid impervious inner liner formed from polymeric or metallic material, a first composite layer enclosing said liner and formed of a helically oriented first set of fibers and of polymeric matrix having a modulus of elasticity greater than 100,000 psi (689.4 x 10 6 Pa) an exterior layer external to and enclosing said first composite layer, said exterior layer being an outer protective layer providing wear resistance and having an outer surface with a coefficient of friction less than the coefficient of friction of said composite layer, and wherein said liner and said composite layer and said exterior layer constitute a composite tube having a tensile strain of at least 0.25 percent at the point of maximum tensile strain when spooled on reel and while maintaining an open bore configuration.

33. A composite tube according to claim 27, wherein said exterior layer is a pressure barrier layer.

34. A composite tube according to claim 27, wherein said exterior layer is an outer protective layer providing wear resistance and having an outer surface with a coefficient of friction less than the coefficient of friction of said composite layer.

35. A composite tube according to claim 32, wherein said outer protective layer further comprises a composite formed of a fiber and a matrix with a particulate.

36. A composite tube according to claim 32, wherein said fiber in said outer protective layer is aramid.

37 A composite tube according to claim 35, wherein said particulate is selected from the group consisting of ceramics, metallics, polymerics, silicas and fluorinated polymers.