Paper Chokes for Unloading

8/13/2019 Paper Chokes for Unloading

1/7

Using Chokes in Unloading Gas-Lift Valves

Prepared for Presentation at the2001 ASME/API Gas-Lift Workshop

Februar ! - "# 2001

$

%en &e'ker# &e'ker (e'hno)o*+)eon &unha,# i)fie)d Auto,ation +onsu)tin*

$urne Warin*# She)) EP (e'hno)o*# App)i'ations# .esear'h

Abstract

(his paper presents the pra'ti'e of usin* donstrea, 'hokes in un)oadin* IP *as-)ift a)es (hepra'ti'e he)ps to assure effe'tie un)oadin* and ,a proide prote'tion a*ainst erosion da,a*e durin*

the un)oadin* pro'ess It has seera) other benefits that are dis'ussed in the paper

A *as-)ift a)e/'hoke ,ode) has been dee)oped It proides a''urate predi'tions of the *as passa*ethrou*h the 'hoked a)e durin* the un)oadin* pro'ess And# it 'an he)p to ana)e e3istin* *as-)iftperfor,an'e# here the ob4e'tie is to deter,ine hi'h a)e5s6 are open and ho ,u'h *as is bein*in4e'ted throu*h the, (his ,ode) is des'ribed in the paper

Introduction

For ,an ears# She)) peratin* +o,panies hae used 'hokes in un)oadin* IP 5in4e'tion pressureoperated6 *as-)ift a)es ther 'o,panies hae 7uestioned this pra'ti'e (his paper e3p)ains the )o*i'of this pra'ti'e and presents ne eiden'e that shos the si*nifi'ant adanta*es that 'o,e fro, it

(he 'hoke )i,its the rate of *as in4e'tion throu*h ea'h un)oadin* *as-)ift a)e to that a,ount re7uired forthe un)oadin* pro'ess (he in4e'tion rate is preented fro, be'o,in* e3'essie hen the a)e is fu))open

(he 'hoke# hi'h is insta))ed donstrea, of the a)e port# he)ps to ,aintain a hi*her pressure upstrea,of the 'hoke and beneath the seat of the a)e (his he)ps to keep the a)e fu)) open durin* theun)oadin* pro'ess# unti) it is ti,e for the a)e to ')ose# and preents thrott)in* (hus# the in4e'tion rate ispreented fro, be'o,in* too )o due to partia) ')osin* and thrott)in*

In essen'e# ith the proper use of 'hokes in un)oadin* a)es# the a)es in4e't 4ust the ri*ht a,ount of*as - not too ,u'h and not too )itt)e - to ,ake the un)oadin* pro'ess pro'eed ith ,a3i,u,effe'tieness

And# 'hokes ,a proide one other si*nifi'ant adanta*e When a a)e is 'hoked# a si*nifi'ant portionof the pressure drop o''urs a'ross the 'hoke8 it does not a)) o''ur a'ross the port/seat of the a)e And#as stated aboe# the a)e does not thrott)e 5partia)) ')ose6 durin* its operation (hus# the potentia) forerosion da,a*e to the a)e durin* the un)oadin* pro'ess is si*nifi'ant) redu'ed

The Reason for a Gas-Lift Valve/Choke Model


2/7

Gas-Lift Valve/Choke Model age !

For ,an ears# unti) 199:# She)) ;kne; that usin* 'hokes in un)oadin* *as-)ift a)es as a prudentthin* to do


3/7

Gas-Lift Valve/Choke Model age %

'hoke is in 'riti'a) f)o# the a)e i)) ')ose on) ith a redu'tion of 'asin* pressure (he =P+ pro*ra,takes into a''ount a)) of the aboe 'onsiderations and then p)ots a perfor,an'e 'ure of f)o rate ersuspressure (he 'orre)ation proed to be ithin @/-1B of the a'tua) dna,i' tests

I$#le$entation of the Model

She)) has taken to steps to i,p)e,ent the *as-)ift a)e/'hoke ,ode)

1 (he ,ode) has been in'orporated into She))Cs ;WinGLDE; *as-)ift desi*n# ana)sis# andopti,iation pro*ra,? Eer She)) *as-)ift spe'ia)ist ho desi*ns un)oadin* IP *as-)ift a)es'an 'hoose to use this ,ode) A)so# this ,ode) 'an be used an ti,e the perfor,an'e of ane3istin* *as-)ift 'o,p)etion that uses 'hoked IP a)es is ana)sed

2 She)) has donated this ,ode) to the =a)e Perfor,an'e +)earin*house 5=P+6 (he =P+ is a;4oint industr pro4e't; that is operated for the testin* and ,ode))in* of *as-)ift a)es (he =P+has the ri*ht to use this ,ode) to au*,ent an of its ,ode))in* ork And# a)) ,e,ber 'o,paniesof the =P+ hae the ri*ht to use the ,ode) in their *as-)ift desi*n and ana)sis ork

I$#roving erfor$ance of Unloading Gas-Lift Valves using Chokes - Case &istor'

(he She)) EP peratin* +o,pan in the DSA tpi'a)) insta))s 'hokes donstrea, of the port in IP *as-)ift a)es (he histori'a) do'u,entation for this pra'ti'e has been )ost but it has probab) been done to>

1 Fine) 'ontro) the rate of *as passa*e throu*h the a)es as the e)) un)oads

2 A))o the pur'hase and stora*e in inentor of bat'hes of a)es ith a standard seat 5tpi'a)) 1IP a)es ith ?/1! ports6

Gas-)ift endors and other industr e3perts hae 'ha))en*ed this pra'ti'e# but it has )ar*e) re,ained inp)a'e be'ause it has see,ed to ork er e)) and e hae e3pe'ted that there ,i*ht be other benefits

When e be'a,e fa,i)iar ith the testin* of *as-)ift a)es for perfor,an'e2## it as )o*i'a) to test theeffe't of a 'hoke on the *as-)ift a)e (his testin* as done and it shoed a si*nifi'ant 'han*e in the'hara'teristi's of the a)e behaior Mode)s ere dee)oped fro, the resu)tant test data 5b &e'ker(e'hno)o*6# ere in'orporated into WinGLDE 5She))s *as )ift desi*n softare6?# and are pub)ished forthe first ti,e here

Dsin* the ,ode)# e 'an si,u)ate hat happens to a parti'u)ar a)e as the in4e'tion pressure at thea)e is in'reased (he fo))oin* fi*ures sho ,ode) resu)ts for a Ma''o .&-1 a)e ith a ?/1! portand a 10/! 'hoke

In Fi*ure 1# the a)e perfor,an'e is shon at an in4e'tion pressure of 1000 psi (he in4e'tion rate isshon on the -a3is and the produ'tion 5tubin*6 pressure on the 3-a3is At this in4e'tion pressure 51000

psi6# the a)e 'annot open# re*ard)ess of the tubin* pressure (his is shon b the dashed red )ine atero f)o rate 5(he tubin* pressure in this 'ase is at 4ust oer ?00 psi6


4/7

Gas-Lift Valve/Choke Model age (

Closed Gas-Lift Valve)igure *

In Fi*ure 2# the in4e'tion pressure is in'reased to 1100 psi At this point both# the *as-)ift a)e is openhen the produ'tion pressure is aboe about 900 psi Hote the tpi'a) thrott)in* a'tion of the un'hokeda)e as the produ'tion pressure is redu'ed be)o the openin* pressure And# note that the 'hoked a)ea'tua)) trans,its ,ore *as and re,ains fu)) open unti) 4ust before the ')osin* pressure is rea'hedEssentia))# the 'hoked a)e ,aintains the fu))# desired in4e'tion rate a'ross the entire operatin* ran*eand then snaps ')osed instead of thrott)in* ')osed

Unloading Gas-Lift Valve +ith ChokeVs, Unloading Valve +ith no Choke

)igure !

Choked

ot Choked


5/7

Gas-Lift Valve/Choke Model age .

In Fi*ure ?# the in4e'tion pressure is in'reased to about 1200 psi Ho the *as-)ift a)e is open at tubin*pressures aboe about 00 psi (he sa,e thrott)in* perfor,an'e is seen for the un'hoked a)e# and thea*ain the 'hoked a)e trans,its ,u'h ,ore *as oer the fu)) ran*e of operation of the a)e

Choked vs, Unchoked Unloading Valveith &igher In0ection ressure and Thus Larger 1#erating Range

)igure %


6/7

Gas-Lift Valve/Choke Model age 2

? (he ori*ina) intent as that the *as-)ift a)e/'hoke ,ode) 'ou)d be used to si,p)if the pro'ess oftestin* and ,ode))in* an ne *as-)ift a)e (his spe'u)ation sti)) needs to be inesti*ated

3u$$ar' of 4enefits of Using Chokes in Unloading Gas-Lift Valves

(here are seera) knon or suspe'ted benefits of usin* 'hokes in un)oadin* *as-)ift a)es

1 (he *as in4e'tion rate throu*h ea'h un)oadin* a)e 'an be )i,ited to the desired a,ount (herisk of ;oer in4e'tion; durin* the un)oadin* pro'ess is e)i,inated

2 (he prob)e, of thrott)in* in un)oadin* *as-)ift a)es 'an be si*nifi'ant) redu'ed (he risk of;under in4e'tion; durin* the un)oadin* pro'ess is *reat) redu'ed

? (he abi)it to desi*n the un)oadin* pro'ess for a knon in4e'tion rate# and to be ab)e to 'ount onthis rate bein* rea)ied at ea'h un)oadin* a)e# 'an he)p assure that the un)oadin* pro'ess issu''essfu) in its ob4e'tie of rea'hin* the desired operatin* depth

$e'ause the in4e'tion rate 'an be Cfine tuned; ith the use of 'hokes# one standard port sie 'anbe 'hosen for a)) un)oadin* *as-)ift a)es in a strin*# and often in a fie)d (his ,ini,ies *as-)ifta)e pur'hasin* and inentor prob)e,s

(here is a stron* )ike)ihood that the presen'e of a 'hoke redu'es the risk of erosion da,a*e ofthe *as-)ift a)e port/seat durin* the un)oadin* pro'ess

! (here is the possibi)it that the *as-)ift a)e/'hoke ,ode) 'an be used to si,p)if the pro'ess oftestin* *as-)ift a)es ith the API pro'ess (his 'ou)d potentia)) redu'e the 'ost of this pro'essand thus a))o ,ore a)es to be tested

Conclusions

(he un)oadin* pro'ess is perhaps the ,ost 'riti'a) ti,e in the )ife of a *as-)ift e)) If the e)) is notun)oaded su''essfu)) to ;botto,#; or if an un)oadin* *as-)ift a)e is da,a*ed durin* the un)oadin*pro'ess# the e)) ,a suffer si*nifi'ant ineffi'ien' and deferred produ'tion for ,onths or ears to 'o,e

(he pra'ti'e of usin* 4udi'ious) desi*ned 'hokes in un)oadin* a)es has been proen to he)p in theun)oadin* pro'ess# and ,a a)so he)p to prote't the a)es fro, potentia) erosion da,a*e

(he pra'ti'e is re'o,,ended for 'onsideration b a)) *as-)ift operatin* 'o,panies

Ackno+ledge$ents

(he authors ish to thank She)) Internationa) and the =a)e Perfor,an'e +)earin*house for per,ission to

prepare and present this paper

References

1 (hornhi))-+raer is a standard# pub)ished ,ethod for 'a)'u)atin* the *as f)o rate throu*h a;s7uare ed*e; orifi'e


7/7

Gas-Lift Valve/Choke Model age 5

2 API .e'o,,ended Pra'ti'e 11=2 # ;Gas Lift =a)e Perfor,an'e (estin*#; 1st Edition# Januar199 (his do'u,ent 'oers the test pro'edures for f)o perfor,an'e testin* of ire)ine-retrieab)e and tubin*-retrieab)e IP 5in4e'tion pressure operated6# and PP 5produ'tionpressure operated6 *as )ift a)es Pa*es> ?!

? For ,ore on the She)) WinGLDE Gas-Lift &esi*n# Ana)sis# and pti,iation pro*ra,# see theWinGLDE eb site at http>//apps,iths'o,

4. (he =a)e Perfor,an'e +)earin*house 5=P+6 is a 4oint industr pro4e't for the purpose of testin*

and ,ode))in* *as-)ift a)es For ,ore infor,ation# see the =P+ eb sitehttp>//de'kerte'h'o, +urrent)# the ,e,ber 'o,panies of the =P+ are> +heron# She))Internationa)# and Weatherford An *as-)ift re)ated peratin* or Seri'e 'o,pan is e)i*ib)e to

4oin

(he =P+ 'ondu'ts an annua) testin* and ,ode))in* pro*ra, on beha)f of its ,e,ber 'o,panies(he 2001 pro*ra, has been distributed to the ,e,ber 'o,panies and 'an be shon to other'o,panies if the e3press interest in 4oinin* the pro4e't
http://www.decktech.com/http://www.decktech.com/

Documents

Paper Chokes for Unloading