7
b -’fspg~;q~’t- -, l. , ., DRILL PIPE The Design and Performance Characteristics of Aluminum Drill Pipe .,” Abstract . t?, G, BOICE R. S, DALR YMP LE This paper outlines the approach atz~ solutions to the problems associated with -the design and deve optnent of aluminum as a drill ‘stem. for rotary drilling. A current field his ory on tdum tsutn as a drilling tool is included to assist the reader in “judging the selection of engi- neering compromises [n the light of present field per orm- ance and to acquaint the reader with. the present status of aluminum dril stetn in the drilling art. Following proof of satisfactory operation  the first cduminum drill string; 25, more strings ske TabIe 1] have ~gone into. worldwide operational ‘ttse. A study  of their performance indicates: 1) no operational disadvantages, ‘“ 2) compatibil ty wfth. present drilling muds, 3J mlxed- R EY NOL D S M S7 AL S CO . RICHMOND, VA. 1 transfer of stresses and a satisfacto~y fatigue life. This and other design and perf rmanc~ considerations are dealt with in this report. After the development of a satisfactory aluminum drill pipe it was necessar to demonstrate the eeonomic ad- vantage of this tool, This too has be n accomplished and data are available to show the competitive position of aluminum drill pipe. Acceptance of ahsminum drill pipe is attested to by demonstrated success iand by re-orders by present users: Five users have’ purchased’ their second strings of alum- inum drilI pipe. One user has purchased his fourth string. Statement of Theory I i . . . string operat onir are successful, 4) hand and power slips are operational{ 5) .no failures i n the tool-joint area (6) tio problems it? fishing or other special USCS, 7) normal wear on. pipe body compar ble to steel and 8) less than t~rmal wear on tool jo[nts. These facts about the. present operational status of alutnin?tni drill pipe “de-mcmstrate that successful drilling tools can be designed and constructed of aluminum. Field and laboratory studies are continuing in order to improve and expand the u,veof aluminum jor.drill pipe. ,. Introduction , . To make functional drill pipe from aluminum required more than a casual selectior, of engineering compromises. The target was a d@ling tool that would substantially meet the physical characteristics of Grade E steel drill pipe but, if possible, also incorporate the many d sirable characteristics found in low-allov steel drill Ltiue(Grade D) such as toughne ss, concentr ic w%ar ,and, low’embri ttlement rate. If aluminum could be successfully fabricated into de- pendable dr~ll stem, the advantages of this light material should reduce drilling costs. A few of the readily apparent areas of improved economy are: (1) rig investment, (2) transportation, (3) wireline life, (4) hoisting fuel savings and ~(s) hoisting time reduction. On the theory that aluminum drill pipe’ would lower dr~lling costs, a project was initiated about 14 years ago, TABLE 1—REYNOLDS DRILL STRINGS—JULY 1, 1963 length mn~cw: (ftl WNe L h locatlm —,— 41/..1. F+t - ; i: :: .2 7. t; ,“ 148,361 106,2S0 10)::; 3s:254 6S,000 36,176 56,583 19,:00 -, ’...,.. r. 15 9,890 23 4,620 16 6,350 6,563  4 9,550 8 8,500 4,500 1 4,650 ~1/2 . from: Texas. CalIf, Okla. Chile N .E , T ex as N .Z . T ex as Albert a, Canada Al berta, Camda N .E . T ex as , C al if . It was recognized early in the aluminum drill pipe pro- ,“. -.,””W 11. 11,62 77,000 9 8,550 72, N.E , Texas 12,000 gram that aluminum alloys could not be beat utilized in a ,, IS. ,~~::, 61,634 5 12,300, La., Miss. 39,013 3,900 Ok&OmO dbsign that copied the then available steel driil’ pipe. It 14. 11;355 ,’ 1T ,:55 15, S:olo 15,000 Mont. 1;:* was necessary to balance the design, alloy choice, spength, 16, 4,020 9,f70 17, Ulnh .5,010 corrosion and, wear resistance of aluminum alloys into a .* *. 18. Caif. 7,020 4,55s 1 Colo. 19. 4,740 57,351 7,:90 workable tool, one. ctspable of sustainigg_the; spe$ses ~f, ~ ~o.. _._u,s~o. ~.-z .l.?.o. -1&l,: 10,OSO. ._. N , .roxm .,. -. N. O kl a. rotary diiilhi-gr “““ ’ ‘-- ‘“”” 4.in. PiOe The application’ of steei tool jaints to aluminum pipe ,21, 11 ?5z0 113,427 19 5,950 MIs.:, posed many problems in ofder to achieve a satisfactory, ,,2Z  J1 ~. 1” . p ip e 7,020 20:,:S7; ~33 6,100 La., Miss., Tex. 23:. OrfginsS manuscript received fn Soelety of Petroleum Engineers”oflh?e 7,500 * * 24. 6,000 SWdl Arabia 5:800 Aug . S,. 1963. Revieed manuscript received Oct. 80, 106S. Paper me. 1 :; .* ,,-~ : Aleska sented at SPE FsL1Meting held h New Orleans, Ott, 6.9, 196 .  , Cqllf. .* , Uhzh

Design of Drill Pipe

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b -’fspg~;q~’t- -, l. ,.,

D RI LL P I P E

The Design and Performance Characteristics ofAluminum Drill Pipe

.,”

Abstract

.

t?,G, BOICER. S , DALRYMPLE I

This paper outlines the approach atz~ solutions to theproblems associated with - the design and deve optnent of

aluminum as a drill ‘stem. for rotary drilling. A current‘ field history on tdumitsutn as a drilling tool is includedto assist the reader in “judging the selection of engi-neering compromises [n the light of present field perform-ance and to acquaint the reader with. the present status ofaluminum dril stetn in the drilling art.

Following proof of satisfactory operation the firstcduminum drill string; 25, more strings ske TabIe 1] have

~gone into. worldwide operational ‘ttse. A study of theirper formance indicates: 1) no operational disadvantages ,

‘“ 2) compatibility wfth. present drilling muds, 3J mlxed-

REYNOLDS MS7ALS CO.RICHMOND, VA.

1

transfer of stresses and a satisfacto~y fatigue life. Thisand other design and performanc~ considerations are dealtwith in this report.

After the development of a satisfactory aluminum drillpipe it was necessary to demonstrate the eeonomic ad-vantage of this tool, This too has been accomplished anddata are available to show the competitive position ofaluminum drill pipe.

Acceptance of ahsminum drill pipe is attested to bydemonstrated success iand by re-orders by present users:Five users have’ purchased’ their second strings of alum-inum drilI pipe. One user has purchased his fourth string.

Statement of Theory

I

i

.

. .

string operat onir are successful, 4) hand and power slipsare operational{ 5) .no failures i n the t oo l - j oin t a r ea (6)tio problems it? fishing or other special USCS, 7) normalwear on. pipe body comparable to steel and 8) less thant~rmal wear on tool jo[nts.

These facts about the. present operational status ofalutnin?tni dril l pipe “de-mcmstrate that successful dril lingtools can be designed and constructed of aluminum. Fieldand laboratory studies are continuing in order to improveand expand the u,ve of aluminum jor.drill pipe. “

,.Introduction , .

To make functional drill pipe from aluminum requiredmore than a casual selectior, of engineering compromises.The target was a d@ling tool that would substantiallymeet the physical characteristics of Grade E steel drillpipe but, if possible, also incorporate the many desirablecharacteristics found in low-allov steel drill Ltiue(Grade D)such as toughness, concentric w%ar,and, low’embrittlementrate.

If aluminum could be successfully fabricated into de-pendable dr~ll stem, the advantages of this light materialshould reduce drilling costs. A few of the readily apparentareas of improved economy are: (1) rig investment, (2)transportation, (3) wireline life, (4) hoisting fuel savingsand ~(s) hoisting time reduction. ‘

On the theory that aluminum drill pipe’ would lowerdr~lling costs, a project was initiated about 14 years ago,

TABLE 1—REYNOLDS DRILL STRINGS—JULY 1, 1963

length mn~cw:(ftl WNe L h locatlm

—,—41/..1. F+t -

;

i:::.27.

t;,“

148,361106,2S010)::;

3s:2546S,00036,17656,58319,:00

-, ’...,.. r.15 9,89023 4,62016 6,350

6,563 4 9,550 “8 8,500

4,5001 4,650

~1/2 1S,po.

from: Texas. CalIf,

Okla.ChileN.E , TexasN.Z . TexasAlberta, CanadaAlberta, CamdaN.E . Texas, Cal if .

It was recognized early in the aluminum drill pipe pro-,“. -.,””W

11. 11,620 77,000 9 8,55072, N.E , Texas12,000gram that aluminum alloys could not be beat utilized in a ,, IS. ,~~::,

61,634 5 12,300, La., Miss.39,013 3,900 Ok&OmO

dbsign that copied the then available steel driil’ pipe. It14. 11;355 ,’ 1T ,:5515, S:olo ‘ 15,000 Mont.

1;:*was necessary to balance the design, alloy choice, spength, 16, 4,020 9,f70

17,Ulnh

.5,010corrosion and, wear resistance of aluminum alloys into a

.* *.18.

Caif.7,020 4,55s 1 Colo.

19. 4,740 57,351 7,:90workable tool, one. ctspable of sustainigg_the; spe$ses ~f, ~ ~o.. _._u,s~o. ~. -z .l.?.o. -1&l,: 10,OSO. ._. N , .roxm .,. -.

N. Okla.

rotary diiilhi-gr “““-’ ‘-- ‘“”” 4.in. PiOe

The application’ of steei tool jaints to aluminum pipe ,21, 11 ?5z0 113,427 19 5,950 MIs.:, ‘

posed many problems in ofder to achieve a satisfactory, ,, 2Z ‘ J1 ~. 1” . p ip e

7,020 20:,:S7; ~33 6,100 La., Miss., Tex.

23:.OrfginsS m a nu scr ipt r ece iv ed f n S oe le ty of P e t rol eu m E n gi ne er s” of lh ?e

7,500 * *24. 6,000

SWdl Arabia5:800 ‘

Aug . S,. 1963. R evi ee d m a nu scr ipt r ecei ved O ct . 80, 106S . P a per m e. 1 :; .* ,,-~ :Aleska

sent ed a t S PE FsL1 Met ing held h New Or lea ns, Ot t, 6.9, 196 . ,Cqllf.

.*, Uhzh

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which has today progressed to “a point of full-scale magnL-tude throughout the world,

Acturil field operation (25 strings) ot’ ahvninum drillpipe has brought to light other advantages and “savingswhich were not apparent at the outset:” 2 (1) pipe main-tenance and life, (2) drilling fuel, (3) tool joint life, (4)pumping fuel, (.5) safety and (6) less flow resistance inannuhts.

Description of Test Eqsdpmetit

F s s t i gu e Te s tA rotating, cantilever betun-type fatigue test tnachinc

is’ maintained in the Reynolds’ Richmond, Vs., labora-tories for full-scale fatigue testing of drill p~pe and drillpipe-tool joint assemblies. The machine has a drive

mechanism in the head which provides a controlled con-tinuous rotation.

A deflecting mechanism is located approximately 7 ft,from the head and is equipped with rollers to provide ro-tating support of the test section. The machine is capableof subjecting a test specimen to a bending moment of200,000 in.-lb during a typical test. Fig. 1 shows a schem-atic of the test machine.

Te ns io n a n d To rs io n Te stA, combirai?ion, tension and. torsion testing machine is

maintained at the Reynolds’ Extrusion Milt in Phoenix,Ariz., for’ testing full-scale specimens of various shapes,.including drill pipe with tool joints. The machine is sxtp-able ‘of a 750,000-lb tensiIe pull, and the heads can berotated 3 60 0 in either direction. Fig. 2 shows a sketch of.the arrangement,.

Application of Test E ipm*

F n t ig u e Tes t in g“ -

Sufficirmt background has been developed in the fatiguetesting of hand-applied tool joints on steel pipe to providegood fatigue life pnra’meters. Most of the tests on the 41.4

in, steel drill pipe were run at 300 rpm under a bendinglRefev en ces g iv en 2 1L end o f p ,aue r.

,

COLLiRTOOL JOINT> DRILL PIPE> 1

MECHANISM80’~ I

-+&

II

,.

F -ig. l—Dr ill p ip e a ss em b ly fa t igu e t e st ‘m a c h in e .

HYDRAULIC ,MOTORS & WORM’ GEARS

FOR ROTATING HEADSTENSION ‘~YL[NDER { ‘TOOL ““DRILL \OOL

.

.

. . .

,

F ig. Z—Dr ill p ip e a ss em ld y t e n sio n im d t o rs io n t e st in g.

moment of 1S0,000 in.-lb to produce a bending stress ofabout 35,000 psi at the base of the upset, The deflection of41/2-in, stee] pipe with a lever arm length of 80-in. iS about7/s -in. which is maintained during rotation. Exprience withGrade E drill pipe and hand-applied tool joints indicatean average fatigue life of 400,000 to 600,000 turns orcycles.

Today, aluminum drill pipe specimens give long con-sistent runs in the million cycle range with. test specimensselected at random from production. Breaks usually OC-cur 4 to 36 in. from the tool joint, which indicate maxi-mum efficiency of the tool joint-drill pipe assembly.

The tests on 41X-in, aluminum pipe are also run at300 rpm under a bending moment of 150,000 in.-lb whichproduces a bending stress of about 16,000 ,Psi at the endof ihc tool joint ‘shoulder.’ The deflection of the 41A-in.aluminum is double that of steel or about 13A in. for a Ieverarm length of 80 in, and a 150,000 in.-lb moment. Thispoints up the fact that the aluminum drill pipe can de-flect about twice “’as m uch as steel driIl pipe and still be

, within safe stress limits, ,,,

Te ns ion a nd Tor s ion Te st

The background ,df” tensile t&thtg on 4~z in. Grade Epipe indicates an average value of 450,000 to 500,000lb. Aluminum drill pipe shows an average tensiie strengthof 488,000 lb, ranging from 473,000 to 503,000 lb ineight joints selected at random from production prior torelease of the first string. Tests were made which putthe, tension load through the tool joint assembly. FuII.length joints were u~ed (30 ft). No failures occurred in ornear the. tool. joint area. The break’ areas ranged from4 1/3 to 9 ft from the end of the joint. The test wasmade by gripping the ,outside of the tool joints. The tensileload did not pass through the working, connections of thejoints.) Very limited torsion test data on steel drill pipe wereavailable for comparison.

A field specimen with a service history of 148,000 ftof hole was given an initial tensile pull of 1 5 0 , 0 0 0 lbaft er which one emi was rotated 180° clockwise with re-spect to the opposite’ end. N.o failure occurred. T’hetorquewas then backed off to 120° displacement and the tensiontest continued to a tlnai pLdi of 365,000 lb, at whichpoint a typical tension break occurred in the body, of thepipe. These tests dramatically illustrate the” tough tension .and torsion properties of aluminum drill stem, in the Par-ticular design, and it s ability to accept abuse.

Design Objectives

Initial design objectives for alumisium drill stem ‘con-templated physical characteristics comparable to GrtRie Edrill ‘pipe. The design should be compatible With presentrig practices, drilling methods, fishing operations, drillingfluids and all other well drilling operatiofis.Phase One - —,.

1, To prevent compounding the’ problems associated .with the irstroduotion, of a new product, a decision was ~made to provide steel tool joints with API working con;nections for the aluminum drili pipe. It was aiso assuthed ‘

. th.at.;@gE,”@@bJg.rns~oV~ ved~m. b~.gPP ica iOn..qC.9Ygi hl$. ., ;,...’steel tool joints .to ahsm~num drif.1.pipe would be easier . ‘and quicker to solve than the development of new types,for example, aluminum )001‘jtipt% . t

2. lf possible, the field application and remotial fea;’ “tures of present hand-applied .~ool, joint designs would bcretained. . . .

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.

.,”

.-,

.,.

F

3. It would also be ‘destrable to provide a design whichwould be compatible with present field methods of hard-banding.

4. The first phase of the development program wason 41%-in. cfrill pipe. Upon successful completion of thiswork, 3 Y2- and 4-ki. drill pipes were designed and fieldtested.

5, Due to the increased popularity of the internal-flush drill pipe, all design considerations evolved aroundthe external upset configuration. Selection of this type ofheavy end would also provide better iinherent propertiesfor the solution of slip placement, tool joint applicationand fatigue problems,

6. Because of the recent interest in the subject of an-nulus flow, external ,s treamlining around the tool joint as-sembly was a part of the design? although not mandatory,and certainly not at the expense of other more importantdesign considerations?

P ha se TwoThe secmtd-phase design objectives, depending on ini-

t ial phase findings, included the following.1.’ ‘The development ~f a bore coating for aluminum

drill pipe, (The same methods and processes which havebeen successful for bore coating steel pipe were not com-patible with aluminum.)

2. The development of larger sizes of dr,ill pipe,namely S, 5% and 6% in.

3. Consideration of a drill pipe size below ~% in.4, Development of field inspection methods for ahtmi-

num drill pipe.5. Development of the all-aluminum strin~, leading to

. .

,1-.,,g.1~

;;1... . .:_,._..- . 3 . . ../“

,. ,.. Fig. 3 -Ck o ss -s ec t io n al v ie ws o f drill p ip e: (le f ) p ip e e x-

t ru de d a n d m a ch in ed , (c en t er t oo l jo in t a ss e mbiy~1 “ ir igh t ) c om p le te d jo in t o f n u m im sm d rill p ip e.

..nwrm~new T06 . -

-, .—

. . .— ‘1, ,,,,.

the design of aluminum tool joints or other methods ofjoining the aluminum drill stem.

6. Development of the internal upset pipe to be fabri-cated into 4M - and 5-in. full-hole and extra-hole drillpip? types,

Data available today indicate that all of the initial de-‘sign objectives have now been reached with a minimumamount of diversion fr.m the original concept,

Fig. 3 shows present pipe (A), tool joint’ assembly (B)and complete drill pipe joint (C). One of the second de-sign objectives has been completed, that of the bore coat-ing for aluminum drill pipe and the formal @ering of

, the 51%-in, size to the trade is in the immediat~ future.Also, soon to be announced, and’ to be available to the

trade, is a new and impfoved inspection method designedfor use on aluminum drill pipe in the field. Other secondphase design objectives are in process, , .

Pres@Xion of Design Development ?, .“;Allo y S e kx t io n

Initial studies of alloys for aluminum drill pipe led tothe se[ection of alloys 6061, 2014 and 7075 as possibili- ‘ties, with final selection depending on laboratory and en-gineering studies in conjunction with proposed tool-jc?intdevelopments. Typical tensile strengths are shown on Fig.4. Fig. 5 compares strength-section properties.

The alIoy 6061 was eliminated early in the programsince engineering studies indicated the physical propertiesof this alloy would dictate very heavy sections. Alloys2014 and 70’75 were carried through laboratory studies,prototype and ffeId developments in various cordlgurations,leading to a final conclusion and selection of 201’4-T6 asbeing the most suitable aluminum alloy for fabrication ofaluminum drill pipe at this time. J

Principal among. the factors leading to this decision ‘wasthe fact that fatigue endurance of 707S-T6 alloy, as re-ported, in AN C:5 (see Fig, .6) was slightly inferior to2014-T6 in complete stress reversals at 500 million cycles,showed a wider and mdre uncontrolled scatterband of re-si.dts, equal-to-inferior fatigue properties in ptill-pull fa-tigue and definitely inferior properties at elevated tempera-

ULTIMATE TENSILE STRENGTH

.,

.

- “ 4 H , - .

- .’ .-~,

.,, .,---- ,.

-., ,.~.—.. ,:-..,

. . .-. . . . . . . . . . . . . . . . . ’ ---- . .. . . . . . . .. . . :. . .-= . : . . ’ -. . --.. -+ . . . . .,. :..

- ..-. . . . . . . ..--. ; ‘-. ~. . ’. - .:---- ‘ .. ’ . :. . . . . . ...

-= ‘- . --.{: - :. . :> : : :. . ;. , .;

. .. . . . . - . .-. .’ - _,.. ,-., ,. ---. . . . . . .. -., . . -.

. . . ,.

:.:.;,. ..-.”.

1707>,

rig. 4 -4 J n it t e ns ile p ro pe rt ie d... . .

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- -------.,

-..

tures (Figs. 7 and 8). Of almost equal consideration werenotch sensitivity and susceptibility to stress corrosioncracking in the full section (both fact~rs being morefavorable to 2 0 1 4 -T6 t h a n 7 0 7 5 -T6 ). I

De sign o f Pip e Bo dy

Alt h o ug h 7 0 7 5-T6 alloy displays a higher unit strengththan 2014-T6, it does not follow that this factor would

provide advantages in a drill-pipe design of 7075-T6 alloyintended to have physical characteristics similar to GradeE. To match the physical characteristics of Grade E withthe 7075-T6 alloy dictates a body cross section comparableto Grade E. The resulting relatively thin wall greatly influ-ences rMll pipe life. Fig. 9 clearly Ulustratq the dkadvan-

yJTKJN ARSA

O.D. INS ,

I.D. INS.

TENSIONYIELD-15.

ULTIMATE-LB.

ACTUAL-LS.

TORSIONYIELD-IN-LB

-—

.-

4,540 6.440 4+407

4.625 4.600 4.500

3.951 3/500 3.S26—.

319,000 373,000” 330,000

363,000 412,000 440,000

. . . . 4ss,000 490,000

363,000-J__

396,000 372,000. ..— .— ——

Fig. 5 —S t r e n gt h - se c t i on c o m p a r is o n .

g ‘o.%g 20

v) d

10

010’ 10’ 104 105 10’ 1(7 10’ lo’

Cycles .-

F ig. Ro t at ln g-be a m fa t igu e s t re n t h o f s h ar p ly n ot ch ed tJo u nd s p e cim en s 2 01 4-T6 a n 7 07 5.T6 a llo y s

(ANG5 , Ma r c h , 1 9 6 1 ). ~

., Tempera ture, F

‘Fig. 7 -S t re n gt h a t t e m pe r a t ur ~’2 0 1 4-T6 a n d 7 0 7 5-T6a llo ys , e xp os ur e 1 ,0 0 0 h ou rs (ANG5 , Ma t ch , 1 96 1 ).

~,,.

tages of the lighter 707$T6 section at elevated temp&a-tures, A slight amount of body wear will substantially re-duce the tensile strength, itxernsl pressure capacity, col-lapse pressure, torsional strength and column strength(see Figs. 10,11,12 and 13). ‘ ,’

In matching’ the physical strength of Grade E with the2014-T6 alloy, a design was developed which provides arelatively thick wall section, thus allowing a substantial

amount of wear before a serious reduction in the strength.,

.,

% i 7%mTHm

,,

.0 --~;r .200

300 400 500 ““.,

,Temperature, F. I , IF ;g. 2 --E ffe et o f t em p er at u re o n m o du Iu s o f e la st ic it y . J

.12 2 5 ,0 0 0 . 7 0 7 5 -T1 5.-: ‘ (AR E A 4 . 5 4 s q . lr l .. , ,, , . , , ,, , , . , . . , ,, . ., , .

.

/(AREA-6.4405.ci. n.1~—-.

.. I emperarure, r .

Fig. 9—Teneile yield i o a d e at elevated temperatures of2014.T6 and 7075-T6 4 @n. a l t d n u m drill pipe.

I

.:, _,: .. __:: . ... .“ .,.. ’..p ..:,._ : . . . . :..-.:. _-... = -.

”-. .. : ;.-.: .,” .” . ;. ..” :. ’----- “...””-.:”-. . .” .. . . . . . . . . . . .. . . ... - ---

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.-,

.‘

.,

30 I I I 1 : . .: .:

3“ 57 ‘ , G,ade E SI.A-2 1.90 22.9 lb/f i )

:2 +- 4 ” ’ Grade E Steel-16.60 [17 .9 lb/ ft }y-. 4 Grade E Steel-1 4.0 0 II 5 .6 l b/ft 1

- ~-: 3W Grade E Steel-1 3. 90 II 3. 8lb/ ft I~:~

27,. Grade ESI,+1 O.4O[ 10.9 kdft )

1’ t 1 . ...--. ..— . .. . 10’ 48121620 “IncludesTQOI Joints

Mud Weight-lb/ed

Fig. 1 4 -Bu oyr m cy ‘“o f a lu m in um a n d s t ee l d r ill p ip e ,we igh t p er foo t .

fabrication of aluminum pipe, ww modified to produce athick wall at the pipe ends and a th,inner wall in the mid-section of the drill pipe. These variations in wall thicknessdo not involve forge upsetting or other metal working op-erations that might induce metallurgical or structuralfichanges in the drill pi~e.

La bo ra t or y De ve lo pm e n t o f De sign s

The modified extrusion process for producing heavy-end pipe was preceded by many other forms of aluminumdrill pipe. First attempts comprised API 8-round-threadson plain-end aluminum pipe. A short test string was fab-ricated. in this manner and tested in the field, providingsome favorable insight into the future possibllititi of ahtm-inurn as a drill string. More strength was found necessaryfor the tool joint area than could be ~btained by the useof straight-wall pipe, One ~arly attempt to design a- pipeend reinforcement consisted of, an aluminum sleeve in‘combination with plain-end pipe.

Several versions of these composite pipe ends wereprepared, tested and abandoned. Other designs took the”form of composite pipe ends in conjunction with plasticattachments for the end sleeves and tool joints. None ofthese, designs was found satisfactory so other methodswere considered.

A method of formigg hot upsets was deveIoped whichprovided a thick-&ti portion for ~ol joint attachment.Tool joints were developed for this type of pipe and test-ed in the laboratory. The results looked encouraging anda 2,500 ft test string was fabricated. This method anddesign was abandoned after field failures developed. Thetrouble was finally diagnosed as inconsistencies in theupset ends, and no immediate solution appeared to beavailabIe for correction of the trouble. Additional designmodifications were also indicated in the. tool joint andattachment area. These tests led to the development ofthe h~vy-end extrus;on process which proved to be theanswer. . ..=

Tire heavy-end extrusion process provided pipe which...-.+.=.P.r.wA@ I@e @@s@@” afigW p@i3e i~sz?x<g entJoy ,

joint tittachment possibilities, good design prospeets-regard-ing stress transfer and p~ovided an easy means of hand-ling. the pipe with slips. F6110wing each series of fatigue“tests,.chang~’ were made in the tool joint and/or attach-

,. ment assembly and a new series of tests run to determine‘ the degree of improvement.

S t e p by step, in this manner, the fatigue life of alumi-num drill pipe and tool joint assemblies was increaseduntil it matched and then exceeded the fatigue life ofsteel pipe. The tests compared aluminum drill, pipe andsteel drill pipe run under the same bending load, but itis to be recalled thit the aluminum “deflects about twiceas much as the steeL W ~.enthe aluminum pipe is loadedto deflect only as ml~ch as the steel diill pipe, the fa-tigue hfe is 5 [0 10. tunes in excess of steel pipe ,fatiguelife. .

Field History

The 25 stririgs now in use “have been subjected to abroad range of operating conditions, as outlined in theabstract.’ Most of the strings are used for conventionalrotary drilling. One string is operating exclusively .as aworkover and remedial string. At present, no operationallimitations have been experienced with aluminum drillpipe.-” Some contractors have “tested” a few joints ofalttrninum drill pipe in a steel string,’ but the identity andevaluation of the advantages of aluminum drill stem, can- .not be brought to light with this arrangement.

Where contractors have added aluminum drill pipe toexisting steel strings tiley have been able to reach lowerproducing zones wfth their present drilling equipment and ,with a minimum of new equipment expense. The historyof driiling with mixed strings indicates successful and im-proved performance. The benefits derived from this typeof operation depend on the compatibility of the mixedstring with the associated drilling and equipment factors.Experience with mixed strings has emphasized the needfor matched externai tool joint configurations to avoidloss of time and effort in changing elevators.’ :, <

Some of the’-fbst strings in service (without the benefitof bore coating), developed moderately severe corrosiork.. “.erosion attack in the bore. The attack was correlated to ‘massive additions of caustic to the driliing mud. Operat-ing practices have bem revised in the matter of chemicals.added to the mud.” No pipe has failed in the field from

internal erosion-corrosion.in generai, low-addition, low pH muds have provide~i . +the best performance with aluminum drill pipe to operatein virtually afl drilling fluids.

In” direct contrast to the rapid deterioration of ferrousmaterials which generally occurs in the acid fluids, ex - -’perience so far with aluminum drill pipe in hydrogen ‘suIfide environment and other acid fluids indicates suc-cessful performance.

Even though aluminum driii pipe has been used SUC- ‘cessfully in wells which display bottom-hole temperaturesof 279F, it is recommended at this time that long-termservice above 250F be avoided. From Fig. -15 it wiil beseen that the fatigue endurance limit of 2014-T6 is near10 million cycles even at a temperature of 300F and,a,fiber stress of, 16,000 psi. This .is 10 times the laboratoryfatigue requirement for the tool joint assembiy at room ,temperature. ‘ .,

Th$ heavy:wal~ transition zones have provided good pipesupport in conjunction with both hand and power slip as-

‘semblies. Damage to the transition zone by the slips hasnot been a problem. “ , .- ;.‘Theje-h;ve ‘be~h-no-‘fiiltir=&Y=inor-“neaf-tli~”-tool-joint-” “-“‘“--

arka, . 1Straightening of the aluminum drill pipe is riot recom-

mended, nor has it been necessary, Some pipe has beenbowed but, in general, drilling with the pipe in tensionstraightens the bowed @pe.

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I 1,006,000 10,Od@OO 100,0&I,Of)O 500,000,000

Endurance Limit-Cycles

Fig. 15—Fatigue e nd u ra nc e o f a lu m in um d rill p ip e n lio ya t v ar io u s t e m p er at u re s.

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There have been, no cases of aluminum drill pipe failingor being damaged on fishing jobs. Fishing tool companiesreport the performance of aluminum drill pipe above their iexpectations in e$ery case.

06 one occasion a fishing tool company “discovered”aluminum drill pipe on the job when its magnetic free

point indicator failed to work. Mechanical or electric-,mechanical free point indicators are recommended foraluminum drill pipe.

So far, there have been no cases .of abnormal pipe bodywear on ahuninum drill pipe. The wear rate appear: tohe comparable to steel. Because of the heavy-wall sectionon aluminum pipe, more wear can be accommodated be-fore down-grading,

There seems to be a definite ,trend towards less tooljoint wear. Eight out of 16 rigs show less than averagewear’ on the tool joints six show average wear and twoshow slightly more than average wear by actual con~-parative. measurement. So far, no eccetitric. tool joititshave been observed on aluminum drill pipe.

The lower axial forces, due to “the lighter weight ofthe aluminum drill pipe, reduce the -contact forces be-tween the tool joint outside diameter ttnd the”wall of thehole, especial ly thr~ugh the crooked sections, thereby re-ducing the rate of abrasion on the tool joints. Further-more, the more resiIient aluminum drill stem negotiatesthe crooked sections of the hole with lower deflectingforces, thtts reducing lateral forces and wear on the tool

, j oints. For these. same reasons an aluminum drill stemrequires less torque for rotation and less power for hoist-iqg than steel drill pipe. “ .‘

conclusions

As a res~dt of 10 years of laboratory work plus threeyears of field history, ahtminum drill pipe in the designref&red to has shown excellent, response to drilling de-mands and requirements as a drill‘item.

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In 1959 u three-phase piogmm wm planned for ex-tensive field testing of the new tool. The first phase ofthe field’ development was the completion of 100,000 ftof drilling-and successful operation by a major oil conl-pany near Victoria, Tcx. This ,was completed near {theend of 1961,

The second phase of development called for place-ment of about 10 strings in the field for further evalua-

tion. The aluminum drillpipe was enthusiastically receivedin the field and 21 strings were released instead of the10planned for the phase two part of the developmentprogram.

The third and final phase’ of ’ahu-ninum drill pipe de-’velopment is prwently under way. M involves the selection . ‘.and establishment of operation policies and preparation of~dditional. engineering data. . .

The” present phase will provide additional data onoperational questions as the use of aluminum drill’ pipegains favor with operators and contractors.

On the basis of present experience it appears thataluminum drill pipe is rapidly proving to be one of the .most efficient and economical drill stems in use. ,

R efe re n c es ,1. “Economic Report”, R ey nold s- M et a ls C o. l’ufllicat irm 732.1.17

(1962).2. Carlisle, Jr., M. E.: “Cos t Analysis o f Aluminum I) rill IJipe.’,.

D ri ll ing Cont ract or May-Jnne, 196.3).3. Hutlmance, W. B.: “HOW to Minimize” Blowouts tmd I.o.t ( lir- ., :

culation”, fVor rM oi l JaII., 1963 ).4. B oioe, E . G .: “Report On U se of .41uminum D rill P ipe’”, World-------- .-.

Ulc iuly lYbJ ) .

5.“What You Shtmld Know About Aluminum Drill Pipe”; oiland f ks ]aar. ?iIwch 18, 1963).

6. “f)rill P ipe E ngin eer in g I ht u.’. Reynollfs J[ t.t als ( k I ’uldiru.tion 732-1-20 ( 1962). M*

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E G. BOICE r ight) is a iechoiccd advisor jor peirrdewntechnology in the Errgineering Services Dept. of ReyIIol@Metals in Richmond, VtI. A mechanical engiizeer, Boicehas been as.vocia~ea’ with the developnient of ahaninamclri[l p ipe since 1955. R. S. DALRYMPLE (left) i s m an agmof t he Petroleum Technology Div. of Engineering Serviceswith Reynold,s. A graduate of Washington State U. with aBS in chemistry, he _has worked with Battelle Memorial

[n,vtitate and General Efecikie. ,. -

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