00013976-through bore subsea xt

8/10/2019 00013976-Through Bore Subsea XT

1/15

SPE

13976/1

THROUGH BORE SUBSEA CHR3STMM TREES

D S Huber G F C Simm~ Hamilton Brothers Oil Gas Ltd

C S J ohnson, The National ~ly ~~ Ltd~Ux

1. INTRODUCTION

Th e work ove r s o f su bse a com p le t ed we lls a r e exp en s ive an d t im e con sum in g

a s even t h e m os t r ou t in e t a s k s m u s t be c a r r ie d ou t by a s em i-su bm e r s ib le .

Th is p ap e r d e s c r ibe s t h e e con om ic , s a fe t y an d op e r a t ion a l advan t a ge s wh ich

led t o t h e d eve lopm en t an d su cc e s s fu l fir s t in s t a lla t ion of t h rou gh bo r e

s u bs e a p rodu ct ion t re e s .

Th e con ven t ion a l we t s u bs e a t r e e s h ave p roved t o be ve ry r e lia ble ove r t h e

p a s t t e n yea rs o f op e r a t ion in t h e Argy ll, Du n can an d In n es fie ld s , h oweve r

t h e com ple t ion s t r in gs re qu ir e pu llin g on t h e a ve r age abou t on ce e ve ry

t h r e e t o five yea r s . Th e con ven t ion a l s u bse a t r e e / t u bin g h an ge r se t u p

d e s ign r e qu ire s t h e t r e e t o be t r ip p e d an d a r ig BOP s t a ck ru n t o pu ll t h e

tub ing .

n :.

.

LS lm Op e ? at lc n

is t im e c on sum in g~ ve ry wea t h e r s en s it ive an d

le ave s t h e we ll t em pora r ily wit h ou t a we ll con t ro l s t a c k on t h e we llh e ad .

Th e 7

1/16

t h rou gh bo r e

s u bs e a t r e e was d eve lop ed t o m in im ize t h e

t u bin g pu llin g work ove r t im e an d s eve r a l t r e e s h ave been ru n s u cc e s s fu lly

s in c e t h e la t t e r p a r t o f 1 9 8 4 . Th e t im e sa vin g on a t u bin g pu llin g

work ove r is t h r e e d ays .

In add it ion , t h e de s ign con s ide rably r edu ce s t h e

h aza rd s an d equ ipm en t d am age r is k s in h e r en t ii i t h e con ven t ion a l d e s ign .

Ham ilt on Bro t h e r s an d Na t ion a l Su pp ly Com pan y in Abe rd een d e s ign e d t h e

equ ipm en t wh ich m u s t be con s id e re d a n ew gen e r a t ion of su bse a p rodu c t ion

t r e e s .

2 . REASON AND FREQUENCY OF WORKOVBRS

Ham ilt on Bro t h e r s h a s op e ra t e d t h e Argyll fie ld s , a s u bs e a sy t em

p rodu c in g t o a floa t in g p rodu c t ion fa c ilit y , fo r ove r t en yea r s . Th e fie ld s

p r e se n t ly con s is t o f 1 8 s u bs e a we lls in c lu d in g 2 wa t e r in je c t o r s an d 5 ga s

lift WMA.

W=U maintenance cost,s fo rm a ve ry h igh p ropor t ion of t h e

-. ..-_. _

t o t a l fie ld op e r a t ion s cos t s ~ e s pec ia lly wh en c om p=ed t o a p la t form

deve lop ed fie ld . Com p le t ion s a r e de s ign ed t o la s t t h e life of

a fie ld . In

p r a c t ic e , h oweve r , a t u bin g pu llin g work ove r is r equ ire d on ave r a ge on ce

p e r fou r yea r s p e r we ll.

Th e r e a son s fo r work ove r s a r e s im ila r t o a n la t fo rm or lad we ll.

Fou r t e en t u bin g pu llin g work ove r s h ave be en p e r~o rm ed

yea r s . Th e r e a s on s , in o rd e r o f frequ en cy, h a ve been :

1 . Re p a ir p roblem s t o t h e DHSV sys t em .

2 . Ch an ge ou t of t h e com p le t ion t o in c lu d e ga s

3 .

Recom ple t ion in an ot he r zon e .

4 .

Dam aged t ubin g.

5 . Sea l le ak s .

ove r t h e p a s t

lift e qu ip m en t .

5


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SPE13976/2

THROUGH BORE SUBSEA CHRISTMM TREES

Th e we t s u bs e a Ch r is t m as t r e e s t h em se lve s h ave p roved t o be an ex t r em e ly

re lia ble p ie c e o f e qu ipm en t .

No work ove r s h ave be en re qu ir e d du e t o a

va lve fa ilu r e . Th is is ve ry s ign ific a n t in t h a t on t h e con ven t ion a l su bs e a

t r e e sys t em , t h e t r e e n eed s t o be t r ip p ed t o p u ll t h e t u bin g. Th e d e s ign

of t h e t h rou gh bore t r e e e lim in a t e s t h is t im e con sum in g ope ra t ion . A

gen e r a l s c h em a t ic of t h e t r e e is in c lu ded a s F igu re 1 .

A t yp ic a l t u bin g pu llin g work ove r r e qu ir e s 1 2 days an d ru n s ou t a t ove r a

m i llio n d olla rs .

Wit h su ch cos t s a t s t a k e , a c on c e r t e d e ffo r t is m ad e t o

m ak e t h e sy s t em a s re lia ble a s p os s ible , a n d t o en su r e t h a t wh en a

work ove r is r e qu ir e d , a m in im um am ou n t of t im e is spen t ch an gin g ou t t h e

s y s t em .

Th e t h rou gh bo re t r e e wa s de s ign ed n ot on ly t o m in im ize t h is

t im e bu t a ls o t o s im p lify t h e con ven t ion a l de s ign con s id e r a bly , an d t h u s

in c r e a s e t h e r e lia bilit y of t h e s ys t em ii Mkd.

Th e t im e savin g wit h t h e t h rou gh bor e t r e e s is 3 days s in c e t h e su bse a

t r e e d oe s n o t n e ed t o be t r ipp ed . Th is is t h e h is t o r ic a l t im e it h a s t a k en

t o pu ll t h e s u bse a t r e e , ru n t h e d r illin g r igs BOP, pu ll t h e BOP an d re -ru n

t h e t r e e .

Th e t im e can be con s ide r a bly lon ge r e sp ec ia lly in m a rgin a l

wea t h e r con d it ion s be c au s e o f t h e p roblem s as s oc ia t e d wit h h an d lin g t h e

r igs 3 0 0 0 0 0 pou n d BOP s t a ck in rou gh wea t h e r .

Th e s e 3 days of r ig t im e

cos t a bou t 3 0 0 ,0 00 USD.

Th e yea r ly s a vin g wou ld be we ll ove r a m illion

d o lla r s fo r a s u bse a fie ld d eve lop ed wit h 1 5 t h rou gh bo re t r e e s ba s ed on

t h e h is t o r ic a l wor k ove r fr equ en cy of on ce eve ry

4 years.

Du e t o t h is

p o t e n t ia l c os t s a vin g, a p ro~am t o d eve lop t h e id e a

of

t h rou gh bor e t r e e s

wa s s t a r t e d in t h e ea r ly sp r in g of 1 9 8 3 .

The

co s t o f t h e t wo de s ign s of su bs e a t r e e s is t h e s am e . Alt h ou gh

in c re a s in g t h e va lve s ize from 4 1 / 16 t o 7 1 / 16 wou ld n orm a lly add 1 5 -

2W0

t o t h e co s t o f a t r e e , t h e t wo t r e e s cost t he s am e be c au s e of t h e

--. .:-- -

.

s im ple r =qu lp~ a b d es ign .

4 .

DESCRIPllON

OF SYSTEM

&

ComwentionalSystem

A sch em a t ic of a s in gle 4

bore , n on -o r ien t in g, we t s u bs e a

p rod u c t ion t r e e is in c lu ded a s F igu r e 2 .

Th is c on ve nt ion al

t r e e h a s n o t c h an ged s ign ific an t ly in de s ign ove r t h e p a s t 1 0

yea r s .

Th e m a jor com pon en t s a r e t h e t r e e an d t h e t u bin g h an ge r .

Th e t r e e con s is t s o f a block s e c t ion wit h h yd rau lica lly

a c t iva t e d f a il-s a f e -do s e p rod u c t ion an d win g va lve s , a lowe r

m an u a l m a s t e r va lve s ec t ion an d a we llh ead con n e c t o r . Th e

t u bin g h an ge r sh own is of t h e n on -or ie n t in g t yp e an d h a s

a c c e s s fo r c om m un ica t ion t o t h e an n u lu s a lon g wit h t h e

fa c ilit y fo r h yd ra u lic flu id t o p a s s t h r ou gh t h e h an ge r t o

fu n c t ion t he DHSV.


3/15

SPE13976/3

DSHuber, GFSimmers CSJ ~

Th e t u bin g h an ge r h a s an in t e gra l ch e ck va lve t o a c t a s a

ba r r ie r fo r t h e an n u lu s . Th is is r e qu ir e d on t h e con ven t ion a l

t r e e s bec au s e a ft e r t h e t u bin g h an ge r is lan ded t h rou gh t h e

r igs BOP s t a ck , t h e s t a c k is r em oved t o ru n t h e t r e e .

Du r in g t h is t im e t h e we llh ead is le ft wit h ou t a we ll c on t ro l

d evice . Th e an n u lu s ch e ck va lve is c los ed wh en t h e t r e e or

t ubin g h an ge r

ru n n in g t ool is o ff t h e t u bin g h an ge r . Th e re

a r e m od ifica t ion s t o t h is de s ign , m os t n o t ably a du a l bor e

sys t em , bu t a ll h ave t h e des ign wh ere t h e t u bin g h an ge r is

la n ded be low t h e t r e e . .

Th e m a jor p roblem s a ssoc ia t ed wit h t h e con ven t ion a l sy s t em

ar e p r im a r ily t h e wea t h e r s e n s it ivit y

of

t h e ope ra t ion ?

p a r t ic u la r ly wh en h an d lin g t h e r ig BOP, t h e com p lexit y of t h e

t ool s and t h e equ ipm en t u s ed .

Th e n e ce s s it y of a ch e ck va lve

an d t h e ext r a h yd rau lic fu n c t ion s r equ ir e d be c au se of t h e

des ign , r e su lt s in a ve ry com p lic a t ed sys t em wit h a ls rge

n um be r of m ovin g pa r t s . Th e se m ovin g p a r t s r e qu ir e fa r

m ore c r it ic a l s ea ls t h an a re n e c es s a ry if t h e t u bin g h an ge r

we re lan ded in t h e t r e e a s s em bly .

A fa ilu r e of an y on e of

t h es e s e a ls can be t h e c au s e of a work ove r .

Problem s h ave

a lso be en expe r ie n ced in t ry in g t o r e t r ie ve t h e t u bin g h an ge r

be c au s e t h e t u bin g h an ge r is lead ed d eep in t h e we llh ead .

Hyd rau lic s lee ve s m u s t be a c t u a t e d t h a t a r e su bje c t t o

s t ic k in g an d fa ilu re .

Th e t h rou gh bore sys t em was de s ign ed

t o m in im ize t he s e p roblem s.

b.

~ BOre System

A sch em a t ic

of the

t h rou gh bore sys t em as su cc e s s fu lly u s ed

is sh own in F igu re 3 . Th e m a jor ch an ge is t h a t t h e bore of

t h e t r e e h as been open ed u p t o 7 1 / 1 6 t o a llow t h e 4 ID

t u bin g h an ge r t o pa s s t h rou gh t h e t r e e va lve s an d la n d in t h e

we llh ead con n ec t o r a s sem bly a rea . Th e syst em a llows for a

fa r le s s com p lex d es ign wit h ou t a ch e ck va lve an d s im p le

s y s t em of Im kin g in t h e t u bin g h an ge r .

Run n in g p rocedu re s for t h e t wo s t y le s

of

t r e e a r e in c lu ded in

Table 1 .

Alt h ough ru n n in g t h e t r e e s in vo lves s im ila x

ope ra t ion a l t im e% seve ra l m a jor s t e p s a r e e lim in a t ed in a

t u bin g pu llin g work ove r wit h t h e t h rou gh bo re t r ee . .

Th e t h r e e day t im e savin g on pu llin g t h e t u bin g is r ea lize d by

e lim in a t in g s t e p s B3 , 4 3 7 8 an d 9 .

Th e t im e c an be

con s id e r ably lon ge r du e t o wea t h e r th e la rge r n um be r of

c r it ic a l ope ra t ion s an d t h e gre a t e r am oun t of wir e lin e wor k

wh ich is p ron e t o h igh n on -p rod u c t ive t im e.

Va r ia t ion s of t h e

p roc edu re s a r e r e qu ir ed depen d in g on t h e p a r t ic u la r ope ra t ion .

.


4/15

SPE13976/4

THROUGH BORE SUBSEA CH

RxsTn sR S

Th e s ys t em is fle xible t o va r iou s com ple t ion con figu ra t ion s in c lu d in g

t u bin g con veyed pe r fo r a t in g gu n s , h yd ra u lic s e t p a ck e r s if t h e we ll is

c om ple t e d in 7 c a s in g} or a s a ga s lift c om p le t ion .

Bot h t h e wa t e r

i nj ect i on w el l s i n t he

Dun can fie ld we re com p le t e d wit h t h rou gh

bo re t re e s .

5 .

ADVANTAGES OF THE THROUGH BORE TREE DESIGN

The

t wo m a jor a d van t a ge s of t h e d es ign h ave be en m en t ion ed p r ev iou s ly .

F ir s t ly , t h e t im e / c o s t s a v in g is e s t im a t e d a t 3 d ays of r ig t im e an d

3 0 0 ,0 0 0 USD pe r wo rk ove r . . Se con d ly , t h e equ ipm en t is c on s id e r a bly

s im p le r by d e s ign an d wit h fewe r c r it ic a l p ie c e s of e qu ipm en t t o fa il s n d

a s s u ch t h e sys t em is ju d ged t o be m ore re lia ble .

Th e o t h e r a d van t a ge s

a r e a s fo llows :

&

Well Control

The well is n ot t em pora r ily le ft wit h ou t a we ll c on t ro l d evic e

d u r in g a t u bin g pu llin g work ove r .

Th e su bs e a t r e e is n o t

pu lle d t o su rfa c e .

? 2 .

~__

P.+-ti.l

f= f-

Danqe

- .- -

Han d lin g t h e t r e e c an r e su lt

m oon pool a r e a wh ile pu llin g t h e

W-c c z su bse z t r e e is la n ded ,

t r e e is t o s t a y la t c h ed on t o t h e

c .

Wellhead Ring Gasket Area

in d am age esp e c ia lly in t h e

t r e e t h rou gh t h e sp la sh zon e .

t h e s a fe s t c on d it ion fQr t h e

wel lhead .

Th is is t h e m os t c r it ic a l a r e a on t h e we llh e ad .

If t h e r in g

ga s k e t gr oove on t h e we llh e ad is d am aged su ch t h a t a s e a l

c an n ot be m a in t a in ed , t h e c os t t o r e p a ir is s u ch t h a t t h e we ll

wou ld m os t lik e ly be aban don ed .

d 8

kmalusmowilrea

.

..1.

L-. bl. -.. -k lsfi.a ~~ee

1

n e Cr it ic a i FLOWar e a t o t h e ixnnuxb on W= L wu5AS UUA =

is abou t fou r t im e s t h e a r e a for a con ven t ion a l t re e .

Th is is

im por t a n t fo r ga s lift c on s id e r a t ion s t o d e c r e a s e t h e

pos s ibilit y of h yd ra t e fo rm at ion an d e ros ion .

e . P r e s a u e

Testing

- Th e p r e s s u r e t e s t in g p roc ed u re s fo r t h e s ys t em s r e n o t

a d d r e s s e d in t h is pap e r .

owever

a m a jor a d van t age of t h e

t h r ou gh bor e sys t em is t h a t a ll t h e c r it ic a l s e a ls a r e in s t a lle d

on t h e t u b in g h an ge r . Th e s e a r e t e s t e d a s soon a s t h e t u bin g

is lan d ed an d r ep a ir s c an be m ade if r e qu ir e d by pu llin g ou t

o f t h e h o ie im med ia t e ly .

On t h e con ven t ion a l Sys t em t t h e

t r e e is la n ded a ft e r t h e t u bin g h an ge r a n d m u s t be t r ip p ed t o

r e p a ir s e a ls on t h e t u bin g h an ge r .

Te s t p or t s be t ween e a ch

s e t o f s e a ls on t h e t h rou gh t u bin g t r e e h an ge r a r e in c lu d ed so

t h a t s e a ls s r e n o t t e s t e d in s equ en c e .


5/15

SPE13976/5

DSEuber GFSimmera C Shhuscm

L

Compatibility with Conventional System

The

d e s ign a llows

fo r a con ven t ion a l t u bin g h an ge r t o be

la n ded in t h e we llh ead .

A s t in ge r a s s em bly m ade u p t o t h e

we llh e ad e ffe c t ive ly con ve r t s t h e t h rou gh bo re sy s t em t o a

con ven t ion a l su bs e a t re e . Th e on iy d iffe r e n c e is t h a t t h e

bore through the

t r e e is

7 1/16 instead of 4 1/16. One tree

has been used in this configuration.

g

Des@ of New Subaea Floaq

Production Facilities

Th e FPF on Argyll is n o t po s it ion ed d ir e c t ly ove r

t r e e s a lt h ou gh ot h e r floa t in g fie ld deve lopm en t s

d e s ign ed in t h is way in c lu d in g Irm e s an d Bu ch an .

la rge d r illin g r ig t ype BOP s t a ck s t o a llow pu llin g

on con ven t ion a l svs t em s is oft e n n o t ~os s ible .

t he s u bse a

h ave be en

Hsnd l i ng

t h e t u b in g

Th e FPF

gen e ra lly m us t be - m oved off lo ca t ion t o_ a llow t h e work ove r

t o be

performed

by a d r illin g r ig.

In ad d it ion , t h e p o t en t ia l

d am age of d r opp in g an ext r em e ly h e avy obje c t lik e an 1 8 3 / 4

d r illin g r ig BOP on a t em p la t e wit h su bs e a com p le t e d we lls

wou ld h ave t o be ad d re s s e d . Han d lin g t h e sm a ll wor k ove r

BOP requ ir e d on t h e t h rou gh bo re t r e e s is a fa r s a fe r a n d

e a s ie r m e t hod .

60

DESCRIPTION OF TREE

a 8

~ ~a~

Th e ba s is of t h is de s ign h a s be en s im p lic it y . Th e t h rou gh

bor e t r e e is n o c liff e r e n t from a con ven t ion a l d e s ign we t t r e e

exc ep t t h a t t h e bo r e is la rge r . Sim p lic it y of d e s ign h as be en

ach i eved

becaue the tree k iid Wtiihd dur~u WOdCOV~~------

operations

an d t h e t u b in g h an ge r is la n ded in t h e p rodu c t ion

Upp er bod y.

Th e s e t wo fe a t u r e s e lim in a t e t h e n e&d fo r an

an n u lu s ch e ck va lve . A com par is on of t h e t u b in g. h an ge r s fo r

t h e t h rou gh Im re Sys t e in

m id =

~wuven~:cn~

.. +--

uy .bG-

re~e=~

t h e s im plic it y wh ich h as be en a ch ie ved .

A s im p le r t u bin g h an ge r le a d s t o a s im p le r h an ge r ru n n in g

t ooL F igu re q c le a r ly sh ows t h e d iffe r e n c e in com p lexit y of

t h e t wo t yp e s of ru n n in g t ooL

Hyd rau lic s a r e n o t r e qu ir e d

an d a s im p le m ech an ic a l t oo l h a s be en d e s ign ed . Th is t oo l is

ro t a t e d t o t h e le ft t o m ak e u p an d ro t a t e d t o t h e r igh t t o

br e ak ou t .

Neve r t h e le s s , t h is s im p le t oo l will r u n t h e t u bin g

h an ge r , t e s t it an d

retrieve

i t , if n e c e s s a r y in a s in gle t r ip .

Wh en lock ed in t o t h e t u b in g h an ge r i t a llows a h igh p r e s s u r e

p a s s a ge t h rou gh t h e

tree

wh ich is u s e fu l in

f r a c t u r i n g

ope ra t ion s . High p r e s s u r e s t r e s s e s a r e t a k en o ff t h e wor k ove r

r is e r , BOP an d t r e e ,

extending

t h e op e ra t in g en ve lope an d

fa t igu e life .


6/15

SPE13976/6

THROUGH BORE

The

SUBSEA CHRISTMAS

lowe r m a s t e r va lve

TR s

an d com pos it e

block va lve s a r e

e s se n t ia lly t h e s am e s t a n da rd de s ign s wh ich h ave p roved t o be

re liable ~ t h e pa s t .

Howeve r , t h e in t e rn a ls h ave been re fin ed

t o p reven t d am age t o t h e va lve s an d t h e s ea ls on t h e t u bin g

h an ge r wh en t h e h an ge r is ru n t h rou gh t h e t r e e .

Th e va lve bod ie s h ave been m ad e s t ron ge r t o ac c ep t t h e

h igh e r load s im posed by t h e w ork over r i ser an d BOP. Th e

p re s su r e an d t em per a t u r e r a t in gs for t h e exis t in g sy s t em a re

5 000 ps i Normal 6000 p s i F rac t u r in g an d u p t o 3 00 F .

b.

Se a l Are a Tea t Por t s

Seve ra l ve ry d is t in c t a dvan t ages a r is e from pu t t in g t h e t u bin g

h sn ge r in t h e p rodu c t ion u ppe r body . Gn e of t h e s e is t h a t it

is n ow pos s ible in a s in gle t r ip t o ru n t h e t u bin g h an ge r t t e s t

a ll t h e se a ls a n d t h e DHSV an d if an y sea ls fa i~ retrieve t h e

t ub i ng hanger.

A secon d advan t age is t h e abilit y t o p rovide a

h an ge r wit h la rge r , u n obs t ru c t ed flow pa t h in t h e an n u lu s for

ga s iiit ap p iic a t icm s . m t h e

eofi~e~t i~~ t siup with ~

0

srmulus

valve,

t h e flow pa t h is u su a lly d ivid ed u p i nt o a

n um be r of sm a ll o r ific e s t h rou gh a s lid in g s le eve va lve

a r r a n gem en t . Th ese sm a lle r p as s a ge s c au s e h igh ve loc it ie s

.- -.-%1 ---

wh ich m ay ie ad t o h yd ra t e pruulcwm.

A t h ird advan t age is t h e r e du c ed h yd ros t a t ic t h r u s t on t h e

t u bin g h an ge r be c au s e t h e t u bin g h an ge r n ow sea ls in t h e

r e du c ed bore of t h e we llh ead . Th is r ed u ce s t h e r equ ir e d lock

down capa c it y by a fa c t o r of 7 an d lead s t o a m u ch sm aIle r

t u bin g h an ge r lock down a re a

c .

Lo ck Down &e a

Th e des ign of t h e t u bin g h an ge r lock down a s s em bly is ba s ed

on an ide a t h a t h as be en u sed for dec ades in lan d we llh e ad s

wh e re s im p le m ech an ic a l an ch or s c r ews h ave be en u sed t o

r e t a in t h e t u bin g h an ge r .

TM? app roa ch is pos s ible bec au s e

t iie t u bin g h an ge r is n ow

loca t e d in t h e p rodu c t ion uppe r

body .

Th is a llows t h e u s e of com pac t , s im p le , low forc e

hydrau l i c segments

The h yd rau lic lin e s a r e d is con n e c t ed

a ft e r lock down bec au se p re s su re is n o t r e qu ir ed t o r e t a in t h e

t u bin g h an ge r lock down s .

On ce t h e s egm en t s h ave been s Iid

in t o p lace a m ech an ica l lock ou t p in is in s e r t ed by d ive r s .

.

.


7/15

. -.

S PE 1 3 1 7 6 / 7

DSHuber, GFSimmers C SJ ohnson

&

valves

Th e 7 1 / 16 EM lowe r m as t e r va lve an d com pos it e va lve s a r e

an e xt en s ion of exis t in g de s ign s fo r 4 1 / 1 6 va lve s .

However ,

t h e e xt e rn a l loa d s im pose d on t h e se com pon en t s by t h e

work ove r r is e r an d BOP h as m ean t t h a t t h e s e t wo va lve s h a ve

h ad t o be an a lysed fo r loa d s n ot n orm a lly en cou n t e re d by

t h e se t ype s o f va lve s .

De t a i led ch an ge s h a ve be en m ade t o

t h e va lve in t e r n a ls t o e n su re t h a t s e a ls on t u bin g hangers

and

running tools w i l l not be dam aged wh en ru n t h rou gh bo t h

va lves .

Th e s ize of 7 1 / 16 was s e le c t ed a s t h e m os t con ven ien t s ize

t o take a t u bin g h an ge r wit h 4 1 / 2 t u bin g an d s t ill a llow

room for t h e DHSV con t ro l lin e .

e

Workover BOP Stresses ad Adysis

Although

t h e

through bore tree has been

run wit hou t a sp ec ia l

work ove r r is e r , a d ed ic a t ed work ove r r is e r an d BOP h ave been

de s ign ed an d bu ilt a s p a r t o f an in t egr a t e d equ ipm en t sys t em .

F igu re 5 sh ows t h e s u bs e a s e t -u p .

Th e sys t em com p r ise s a work ove r BOP pack a ge , a t a p e r jo in t ,

several r is e r jo in t s , a t en s ion co lla r , an d a su r fa c e t r e e an d a

be ll m ou t h jo in t .

Th e BOP pack a ge cons is ts of a 1 3 5 / 8 5 M con n ec t or , 1 1

1 0 M p ipe r am , 1 1 1 0 M sh e a r r am an d an an n u la r BOP. Th e

BOP is sp lit t o a llow h an d lin g by a c r an e of 1 4 t on capa c it y.

A t ap e r jo in t was ch osen in p r e fe re n ce t o ot h e r a lt e r n a t ive s

su ch a s ba ll jo in t s sn d e la s t om e r ic fle x jo in t s bec a u s e t h e

t a p e r jo in t d e fle c t s t h rou gh a sm oot h c u rve wh en t h e r i ser i s

a t an an gle t o t h e BOP.

Th is sm oo t h cu rve a llows t h e t u bin g

h an ge r an d work ove r t oo ls t o be ru n wit h ou t d am age t o se a ls .

Howeve r , on e of t h e con sequ e n ce s o f ch oos in g a t ap e r jo in t is

t h a t h igh e r be n d in g loa d s a r e fe d bac k in t o t h e t r e e t h an

.

wou ld be t h e c a s e fo r a ba ll o r flex join t .

A n on -ro t a t in g p r e loaded con n ec t o r is u s ed t o join t h e r is e r

s e c t i on s .

Th e s e con n ec t o r s p rovid e qu ic k m ak e u p , h igh

ben d in g m om en t c apa c it y an d r e s is t an c e t o fa t igu e . In t h is

--- 1: --.:-_ AL -- --- >-2 ->

appucalun

Lne y

are uemJIJnmA -h 8

elon 1 l~n

319 x

-11

Llk

w aAL

Cnnc

a

--72

p ipe .

Du r in g a work ove r t h e ext e r n a l load s im pos ed on t ? ? e TBT a r e

h igh e r t h an fo r a con ven t ion a l t r e e . Th is is bec au s e in a

work ove r o f a con ven t ion a l t r e e t h e r is e r is o f a sm a lle r

d iam et e r . Con sequ en t ly s it e s p e c ific an a lys is wa s ca r r ied ou t

fo r t h e com p le t e sys t em t o de t e rm in e t h e ope r a t in g en ve lope

fo r t he in st alla t ion .

In c lu ded in t h is was a fa t igu e a n a lys is

wh ich t ook ac cou n t o f t h e fa c t t h a t t h e s ys t em wou ld be u se d

in t e rm it t en t ly (1 0 -1 2 days a t a t im e).


8/15

THROUGH BORE SUBSEA CHIUSTM

AS TREES

Des ign s t r e s s

le ve ls h ave be en in a c cor dan ce wit h DoE

---- :. .m - a -+=

Kcqdu-wu. . .

thoea

~e~~ ---K-

Wm ~~

wit h o t h e r in d u s t ry

s t a n d a rd s wh e re t h ey do n ot .

Th e an a lys is sh ows t h a t t h e

gr e a t e s t e xt e r n a l load s a r e im posed on t h e fla n ge of t h e

lowe r m a s t e r va lve s . Th e va lve is t h e r e for e de s ign ed wit h a

n on s t a n d a rd h e avy wa ll body an d ove r s ize fla n ge s .

Th e op e ra t ion a l e n ve lop e deve loped for t h e Argy ll fie ld wa s :

1 1 .4 8 ft s ign ific an t wave h e igh t

7 1 / 2 degre e offs e t

2 .8 k n ot su r fa c e cu r r e n t

.5 8 k n ot a t m ud lin e

f. New Developments

A weigh t s e t m e t a l s ea l h a s be en de s ign ed an d su c ce s s fu lly

t e s t e d fo r t h e TBT t u bin g h an ge r .

As p re s e n t t h is s ea l s i t s

a t t h e bo t t om of t h e t u b in g h an ge r . Th is s e a l is be in g

deve loped t o p rovide a m e t a l t o m e t a l s e a l a t t h e t u bin g t o

an n u lu s in t e r fac e . Th e d es ign is t a k en from Na t ion a ls 1 5M

m e t a l t o m e t a l s e aL Sea l m a t e r ia l h a s be en s e lec t ed t o

p rovid e a com prom is e be t ween so ft n e s s f or low se a l s e t t in g

load s ) s t r e n gt h (t o c s r r y t h e fu ll t u bin g load s t h e h yd ros t a t ic

*L . .

KJX&L dii~ to

testing ad

F-m .++- fp~~~yri~ ~d corros ion

.- ------

r e s i s t a n c e .

In t h e fir s t ve r s ion of t h e TBT, t h e t u bin g

hanger

la n ded on a

sh ou lde r in t h e

production

u ppe r body . Th e cu r r e n t ve r s ion o f

t h e t u bin g h an ge r c lim at e s t h e sh ou ld e r an d load s in s t ea d on a

C-2 la t c h r in g. Th e C-2 la t ch r in g is a load be a r in g ring

bor rowed from Nat ion a ls C-2 m ud lin e su spen s ion eqy ipm en t .

Th e la t c h r in g la n d s in a p rofile c u t in t o t h e body in s t e a d of

on a sh ou lde r , an d t h e r e for e gr e a t e r c le a r an c e is a va ila ble

be t ween t h e t u bin g h an ge r an d t h e bor e of t h e com pos it e

valve .

Th is c le a r an c e is of the ord e r of 7 / 16 ra d ia l an d

sh ou ld e lim in a t e t h e p roblem of s ea l dam age expe r ie n c ed in

mzwli-P ~~~~i~~~

.- .

Lan d in g t h e t u bin g h an ge r in t h e we llh ead t h rou gh t h e t r e e is

a is o be in g s t ud ie d .

f m t ilh is ivcxdd a t iow t h e ad va i-lt a ges o.

s ys t em s t o be realized an d wou ld give t h e op e ra t o r his cho i ce

even on t h e s am e we ll a s t o wh e re t h e be s t lan d in g poin t fo r

t h e t u bin g h an ge r wou ld be .


9/15

SPE13976/9

DSHuber, GFSimmers CSJ obmmn

~t 1985

Society of Petroleum En@neem of AIME

Th is pape r was p re pa red for t h e Offsh ore Eu rop e 8 5 Con fe r en ce in

con ju n c t ion wit h t h e Soc ie t y of Pe t ro leum En gin ee rs of ~E, h e ld in

Aberde en , 1 0 -1 3 Sep t em be r 1 98 5 . ermission t o copy is r e s t r ic t ed t o MI

abs t r a c t o f n ot m ore t h an 30 0 word s . Illu s t r a t ion s m ay n ot be cop ied .

~.e a bs t r ac t s h o~d con t t i c on sp icu ou s ack n owledgem en t of wh e re an d by

wh om t h e pape r is p r e s en t ed .

Pu blica t ion e ls ewh e re is u su a lly gran t ed

u pon requ e s t p rovided agre em en t t o give p rope r c r e d it is m ad e


10/15

TABLE 1

RUIMMMGPROCEDURES~ SUBSEATREEIJESIGMS

CC)NWI(IWL ~+ ilESk34

THWWH BORETREE

RunnIng Procedure

Al Run production casing. Clloen out tu the float ecd Iar.

c l

Run production casing. Clean out to tho f lost cd Iar.

C2 Olsplacathe casingto brlna. Run

ulrdfno sat packer.

A2 Dlsplaca the casing to a kill walght, clean, nOWdSM)gl Og

f I tarad brl na. Run wl roll I na sat packer.

C3 Pul I

the rlg BW. Run the prodwtlon tree.

A3 Run the tubing string, Iocata the seals In the pucker, mko

C4 Run the uorkover W and rl ser.

up the LNISVassasbly and the tubing hangar.

Land the tubl Ing ,

hangar In the USI I hoad.

C5 Run the tubing string, locate the seals In the packar, mke

up the DHSVassatily and the tubing hangar.

Land tha tubl ng

A4 Run a plug Into the OHSV lnlpplo.

hangar In the tree.

A S Pull the rlg 8(JP. Run tha

gWOdUdlOI t *SO.

Parf orate and f 1 0U tha wet 1. Run the WSV.

AS Run the uorkovor W and rlsar. Pu I the plug

from

the OHISV

C7 Pul I the uorkovar BOP and riser. Wall Is ready for

nlppla.

product Ion.

A7 Parf orate and f I on the USI11, Run the IMSV.

A8 1 1I t~a uorkoverBOPandl rl ser .

Hal 1 Is ready for product Ion.


11/15

RE-ENTRY HUB

T

.

i

ALvE\

q--

A

.

I

uPPER MASTER

~

1-

LOUER MASTER-

VALVE

DHSV

7

r

I

I

7i

.

-WIN6 E

/-Production

~ ANNULUS

LINE

LINE

I

9

,1OLATIOh

VALVE

TYPICAL SUBSEA TREE

SCHEMATIC

FIG 1


12/15

El

iii

5

.. .. .

.... .

. ,..

=

w

t i


13/15

I

M

(

-+1-Ir

HI

I

I

Ill

J

.,*

,:,

;.,

::}

Rii

Ii{:-.~.

w?? -+

IillbR

.,..,,,

;.......

~. &

,*

., :

.. . :

~ ...

.,. .

:

j:,. --: ; .. 6 . ,

~,, , ,.. .

..

...

H m

m...

I r


14/15

--------

- ..-. .- .. --- ------ ----- ,.-

.

..- -=. .. - -.. .

[Ii

ii+

I

. .

-1

:

?. \-\ ..

~

.. . . . .- ... .

\

-. ---- ---

3

---. . .-. .- . --

....---- . ..---

... .. .. .

---

.-.. - - --


15/15

- q

I

I

w

1

r

.

.

la

-

S14

*-7

RAM

nof~

1-=-

i:R=ll

: ;NE~ r :R-

.=

Unl

?~:c

GUIDE FMPE IMLMJ

3-314

:.::

TQFC

FIG. 5

00013976-through bore subsea xt

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