DrBad Drilling Hydraulics

8/3/2019 DrBad Drilling Hydraulics

1/9

Chapter 4ilrilling Hydraulics

{hapx. 2 and 3 ptewtdeii irtirsnnukm *ls


2/9

Fig-{"1*Forccs acling on a tiuid element.

lf we are, dealing wi* a liquid such s.r driliing ntud nrvlt waler, fluirl rr:mpresnibility is negligible, alrtlspecifre weight can be consrdercd constant wirh depih.lntegration oi Iq. 4- 1 ibr an iac*mpressible liq*id givrsp*li*D*.{:s ","....{4.?a}whercpo. ihe, qpnstgnl ol integration, is equal to the sur-faee pressurc {D*U)" Nerrmalty the static sur{acspr6*5ute p6 i* eerv unless the bl*wout preve"n{er {}f thew*ll is elosed afid the well is trying kr flnrr. The spciliew*ight of the liquid in field unirs is gi*en by

APpLrE0 nRlLLt!*G EHni$f ft tr'l$

DRILL PIPEANNULUS CIpr$ HOLS

ILL EOLLANS

Fig. 4.2-The well iluiei svstern"

'flrur, rhe mud density ntusl he at l*ast 13.4 lhrnlgal toprcvent the flow oI ftrnrratiein f]uiti intu thc *cilb\;rcwhen the *'ell is opi::n t.1 the *tmosphere (p6 *ll psrg;anei there is no mud circillati*;r.

'*.1 Hydrr.r tntie Fr*ssure in {ias ColsmnsIn many drilling and camplefion operzlitnl, a gas ispr$lln{ in ;it least a parlion of tlrc well. ln $ome ease;"gar is injec*d in the well liarn the *urfaer: while in olherc:r$es gas may enter the wcll fnrm a ;uhsurf*ee fornla-tion. The variatitln of pressur'* with dcpth in a static g*scolumn is rn*rt c*mplie*tc.d than in * sln{ic liquid ml-uml b*cause the gar densit;' chlnges uith changingIlfeSsurs.The gas bclravior can lx d*;cribcrl u*ing lhe rra! ga:equatian delinecl try

IRMEAgLgZ0!'lEs

lt'*t':S'0-5?P'when f",,,, i: theinch per f*rut andg.ter gallon. Thus

qa .3)

specifit weight in pourrJs per :iq*rnp is thc lluid rl*n*ity in p$undr massEq. 4.?a, in fie1d units, i* giv*n byp =0.052oD + pu. . (4.?b).4n impo*a*t xipplicillion ol _the hydr*slliril: prs$$urrequaliern is lhe det*nuination of thc prupcr clnlling {iuiddersity. The fluisi eqlumn in rhr' well must bc of *uffi-eienl density tt) ca*Ji ihe pressurc in the wctl op;xlriteeach permeable ;rratum to be greater than the porepressure of ihe lirrmatir:n fiuirl in the penr:eable stratrrrn.This probienr is illustratcd in the schemati* dmwingshown in Fig- a.?. Howerr:r, dre rlensily cf tbe fluid eol-r:m* mu$l not tre suffiricnt to e ause any of fh* fcnaalicnscxpvscd to thc drilling {"luiil tr frar'trurx. A fi:ictrrred 1*r-m*tion would ;rllnw sonrc nf the iirillirrg l'luir! abo'vc thellxetr:re deph rr.r lcali rzrpidly fronr the well lnm rhe inr"

tured form:iti*n-

Er*mpfu d,/. Calculate lhr rtrtic rnud rlcn.srlr rcquircdto pr*vni flnq, lrom a p*mreablc slr.rtunr al 12,:00 fi ifih* pnrt pre$sure of lhc fnrmarion iluid is $.5S0 psig,Sr;luti*n. Uriirrg Eq. 4.?b.

p &.s{.Xl ,, I.1 .4 lhnr rul0.()5:i ) o.{)5lt ll.l(I)l Thc gart dt viatiun {.*l:tar : is a nt*a{urt: r.rf hrw nrr-ich. rlri:ga.s lr*havinrcltvietss lhrm th;rr nt an ii*tl;;r,l.r. An itl*tig{; is one in uhit*h ther*;.rrr. n{]t;i{lr*ctivc ffiri*: hefrr,cen

pl'=.;nRT-:-R'f,M t j ,1r*,hcre.

l*

ltl z&{*

ll*fl*T::ibrilul* p{rss$re.,glr v*lunr.nrol*s r:f gas,universal &rs r:flnstrfit,ab$oliltc tenrpcraturc,nrass cl' g:rs,gar nlolec*lar w*ight, iincigas devirriol fact*r.


3/9

ONILLING HYOFTAUI'C$

&a$ m{}lecules. Gas sleviarron lactors ficrr natural gasesheve besa deti:nnias{t *xlxrirnentally ar a funrrior, oi.trnlpem$rc.erd pr*qqrr and Bre readily available in rhep*rul*um li*rararc. l"l In rhis chaprcr the. simplifyinga$$umption pf ideal g*s brhavior wiil gener.llly be ruadeto as*isr the student in f*,uusing more casily on dre dril}-rng_hydraulics concepls being dcve loped. ''I'he gas densiry can be. expressed ar a funeti*n afpressure.by rearranging Eq. 4.4_ S*:lving this equ*rionlor gas dcnsity p yielcls^ _ ,il -* plv['v8T"

pM80.3ef

{lhangiag units frrrnr **nsistent units {* cornrnon fieldunrts glv95

tt$*ll,j!r, The pm;sure in rhe annulul tr a deph of1il"fl)0 ft is giv*n by Eq. a.?h.

p: *0.t15:{9"0}tlt);fiX}) * 14.7 * 4,b95 psia.pryres.sqre in the tubing ar a deprh n{ l0.tXr0 lt is give nby Eq. a.6

16!!o:ljlilp I : l _{J{Xie 1.5;14{t}{.460r l4llJ * i, }*g p*ia.

Thus- thc prss{urc di.ffercnce ir giv*n byltz * F t *4,693.* I . I llfi *3,5fi? psi,

which * canrideiubly belorv rhc coilapse preslrurr o[ thetubing.I'lie de*siry af ihe g;rs in th* tubing at rhe lurface c*ukibe approximated u*ing f4. .i.5h a* ii:llows"l ,{t0ri{ 16)F'- ::-:-:*rt-:::: *0' 33 I lbrri/g*|.80.3tlx(iOfj

Ir is interesiing la note lhar rhe usc r:f this ckn.ritv in Eg.4.2b givc.s,p 1 :0.051(0.331X t0,t$0i *. I.tX$= I,l7? pna,

whiclr is wirhin 16 p;ii *f the tns\tcr rt*aiaed using themrrc, crxrpler. Eq- 4.6.

- . {4.5a}

{.{.ib}wh*re ,r ir exprcssed in peundl nali$ p. gallo:r, p is inryu{* Ixr ${uam inch atrsolute, *nC fls in degrccsRankinc.tArilen the lengh ot th* gas colulrln is nut great and theBa$ p;essure is abnve 1,000 psia. rhe hyclist*tir rrqur,tiprt for inr-*mprrxibl* liquirls givcn bi. Eq. +.lh can beused tcg{:Lhcr *ith Eq. 4.5b withour'nruih l*ss in ac_e$?ey, hnveVer, rvhen the gas colunrn is not shon orhighly pressur*d, the variarion of gas clensity with d*prhwithin the ga* er:lumn shrruld tre tiken into ,reerrLrnt. Us-ing liqs. 4, l- 4.3, and 4-,5a wc obrain

0,05? nMtlp '- .-.-'''''--&rj.u0- I :7tl the v*riation in e within the gas column8rcnt. \ve can treal t 3s a (.onst:,lnt . l.variables in the ab.vc equarion vreld.,

t/I M ,!)I -Jp=-.---1,1p;,:,- P 1,-ra-l ;l"i.a]lnlcgration of rhir equarian givrr

All{ -ll!1l.tlJ:?f ' t'tt

4.3 Hydroststic Pres$nrc inComplcx Fluid ('olunrnsDuring many drilling opcrnri{lns. ihe well flui


4/9

'1 r6

Dn0;O2

Sp

*a

Dn-r

06Flg. d.3-A q'mplex liqriid cclumn'

tt is frequcntly rJerirable lo viev* ths wdlJluid $ytmshown !n Fig. *.: tls a mnnometer wh*{ sclving fur thepressure at i giuen point in the wcll. The drillstring in-ieri*:r usual$ is represented by rhe left sida "9f thefis,noffi&{&r, and the annulus usually i* repr**ent*cl by theriglrt sidc ol the manometer' A hydrosrarie prssriurcbilanee e*n ahen be wrinen in lsrnrti r:f a k*ewn prFsureand the unknQwn presssre uring Eq' 4'T'

l-118 {ml

IItI

30*tr$Il?00fral

t000 fcllFig. 4"4*Viexing ths wetl ss 8. msnom*rer.

and the chnng* in hytlrostatic pressurc is aclded to theknown pre$rarcl cr,nvcrsely, when alcl'ing $p through ercction. |tli+t-fri is ne&ative and rlre chang* inhyrlrn*tatic tre:isure is suhtracted fr$m the kre\t.,nprc$sure.

po *p s *0.S5? t I $.:t?.{l{Xi} r-fl . 5(3t}0i+ l?.?{},?0q) + I 6.?t 1,ffiOi *9.0{l $,{xxll'

$irce ths knrwn pressun p6 i; 0 p;iig' *enpo : l,?66 psig.

4.3.1 Eguivalert t)nsity ComeP{Field experien*n in a given area o&en *llaws guidclinesto be dcvcl{rp*d f$r the ma*imutl nruil dcnsity that f*r-mntioffi at a givcn clepth will withttiand without fracfur-ing during nonnal rlrilling opefiltion$. ^lr is.sometimcshipful to compare a *unrplel *'ell fiuid ct:lumn lqr an*quiralent ringte"nuirt cnl$mn that is apcn to the a{-nrosphtrr. Ttis is $ceollflistred by *calrulatrng rhccquivalenr murl d,:rrsity p". which is de [ined hy

APplls *RlLLll',G El*giN{EalG6p. * stfnslPll'tit tr*ttirr,

i{ .8}

Ll.tt-ptt--F-

I

LaI_l-

LnI

Et*tnple 4.3. An inttmedia{e cail,Lg.sring is-,lo beeemented in plate at a depllt *f 10'fiff1 li. 'fhe well con-tair* 10,5-lbmlgal nlud whsn rhe c*sing *tring ir pl*cedon bfiron. The cementing operati*n is desig*r.d ** thatthe 10.5-ltlrnlgal nrurJ rvill be displaeerl fr*rrr rhs annulusby t1) 300 ft of t.:-tUnitgal nrud fluth, {?} l,l0n it qiti.?-lbmlga: filler ce**nl, arr:l (31 t,iJ00 {t of16.?-lhm/gal higi-strength {{:m*nt-'l'hc hrgh'strtngih{ftenl will le dlsptaeeit fitxr the casing with 9-lbmlgalbrirrs. Calculate the pump prc$surc rcquired in conrplete-iy rlisplaee thr csnrgnt fmn: tht casirg'Srrllr;ir.rrr. Thc campler well lluid r*y$ttm is unilerstoftlmoro ***ily if vieu'ed fili a mlnotflerer {Fig' 4.'f). Thehyrtralttti* ptet;$ur* b*lafice is writt*n lry rtadirrg at theknown p*:luril *ncl mrrnirrg thraugh tlrr vtrir*rs lluitl$q{lii:ns n rhe prrint of tltr unknown pmssurc Whcnmoving rl*wn through a tieclioR, t0,+t*bi ) is pi:srtivc

{}D": --. .0.0_12I)Th* cquivaicnl mrrrl dtnsity alrvrys shr:uld b: rcfcrerne'lat a specil'ind depth,

Examplt 4.4. {lalculate the equivaient den*ity lrl t.de{'thof 1il,0{$ ft {*r [xarnple 4-3 {crr statit well co*rJitinnrsfter the {:rtnat}i hss lxr$ di*placetl conrplcely fror:r thcc*sing.5,,lutirtn. At a ,Jcprh trl 10.(Xr{) lt,

r; = $,05?i9. {}}{ I 0,{XX}i + i .}66 * J'9;lf' p*i g


5/9

FRILLIN* HYSNAULICSU*ing f;q. 4.8.

5,94bor =:-:::-----:::- = I l.{ lbln/gal.0.0_52 (10,00oi!i,3.1 Hflb{t *f fintrainrd Solids and Csre{in tlrilling Fluid*rillitg e*ginerx s*lilom deal *ith pnre liquidr i:rg$$ei. Fqr cxample, both drilling {luids and {cffient* srepiimarily a miriture *f w*ter and fi**ly diviel,:d rolids"The drilling mad in ihc annulns also eonrai4x thc drilledsolids fr*nt the xrek brvke n up by rhe bir and rhe florma-tj*n fluids. th*t were eontained in the mck. As long a; thefiareiglr nlarerial$ arc saspadrd by the lluid or seulingthrough the l'luid at their rcrrnina.l velwiry, the effer:r rii'&e {oreign $ulsdals on hydnrstatie prtri$ure can be corn-pulcd by rcplacir,g &s lluicl clensiry in Hq. 4.?b with rheden*14, cltlre mixturc. However. particlcs that hul,e sel-tled *ut of Lhc iluid and src supporred by grairi-to-gruincontact do not influence hytlmsuttc prcssurE.The dcnsity Lrf an ideal nrixtun: can br crrnrputcd usinpthe rqle ulation pruredure dirscussctl in Sec. ? of Ch*p. ?.The avcr,rge density of a mixture of several c{imtxlnentsi* give* by

11?

lvh*re M is :he averxgc *nle*utar wrigh{ of the ga*.Felr comnrcn field units, s*b*rituri** if this exp&ssi.,nf1r"ryean dcnxity in tq. 4"3 and cnnrbiniag wirh q. d..lv iclds

"D, ,p\j '-:J'n1 Pt p+1tfrfrI di,13,05?fu1+,1r'$") pIf the variatian af ; and I i* nat trx) grcet cver rlre eitlumnlength r:f in{ercJit. t&ey cnn be rrcererl u, *un-sunls $f rncsfi v&lu*s e and 1-. lntegmtion of [r1, 4. l?g:ive;Ft-llt l, Ir:Dz-D * u Pi (4. I 3;

wherea*0.f5? lpya"MV"), , ".. .{4.14i

andb:2N,,8. .. . .. {ji.ts}

It ix unfonunete thst {hs prrs$ure f 3 &p}rearx within thek:garithmic term in Eq. 4.i3. This means thar alriterative calcutr*ir:n pnrcrdure musr be used for rhedctenainatiein of the change in prcsxure with el*rnstrpnfnr a gns-cut lluid colunn. Hi:rwever, il rhe gaslliquidmixtulr is highly pressured and not very long, the v*riu-ri*n of gas density wirh pressure carr be ignor,l. In rhisf&se, lh ririxtxrc ilensiry , given try Eq. 4.1t ran hsa&s$fisd f,crl.ctant and rhe change in hydrrrstrti* presrurscso be campulcd using f:{i. 4.1b.

(4.1?)

lt ,t!-2t'r, L *riv,i= I i=l,,* -;-X rn, X r',i*l f*l

ft: ), p,J,,i.- t " {.t-s}a'hew n i, Y i, p i, an&| ass llte n'ra*s, volumr. rlensi ry,and volums fiactian cf compnent i, resp:crively. Asl*ng a* th* t:*ffip*nsnt; a:e liquids anrl serli


6/9

0

* 4dd6t$, rooo6

AVF*Ca glrsrrY sF 6A5C$T i*UO,*gst,rtt lA{!r lgalll!.

fig. 4.$*Annutar donsiry pls! lor xamBle 4.5.

f,trillcd r*lids arc berng *ddecl lo ihe dnlling fluirl at al"t* t]f3.3 l{l -0.2,t :2.6.5 gal/nrin.

Fnrmati*n wnrer is being added to the drillirg il*irl at araie of3. 3l i0"?X0.3ll *0.2 Sallrnin.

?he d*nrity ,:ll'lhr drilling liuid aftcr the iarclilion ol thcwaler and drillerl serliels rvould bel4(350) + ? r .9(2.65) + 9(('.2)

350+ 2.6.1+0.2* i4.05? lbmlgal.

Methane gas is beiag addrd ta the drilling lluid at a ratcof

.1-5b i*

APPLlED SRILLIIIG ENGI'{EERINGL?*ing [qs" 4.14 and 4. 15 give*

$ *0"051[ 1a"05? + l4{$.0ff]?3 I }l :0.73 I ?"iind

6:{1X0.00CI?: 1X80.3Xs20} * I 1.5,Since fhe rvell i* apcn to the atmnsphem, {he surfa{epres$ure St1 is 14"7 psia. 'Ihe botlomhsle ;:rc$sure p1mu$t bt: crtimeted l'rom Hq" 4. 13 i* $n iterstiv$ fflanner.As shcwn in the r*ble belgw, variou* values fcrp: vr?a,ssumed until the ealculated {Oz -I}t } wa* equal to thewetl depth of l?,fi00 ft"

Thur;, the elia*g* in hydrost*tie head due tc thr drilledfarmation nraterial entering the fiud i* givea by

nl F:-F tt:?lirl 0,7?178,?50 1l,t468,7110 r r,8788.716 l l.!{,}CIar*8,716*'6

fst3.32 tnfi fiz*fit-m".fi_-- -',?.0+6t00..1.1 j I .g7Rl*n.3? iJ,0{na4 I

Yi7fr(

y t u.';';1",*fu=u#rY'\:* #;: t' ';tvn\ i #Y8'*-" 'd*rnnring {hr: gas is icti:al and *re formution pressurc is;rpproximat*ly 8,?51 psia. the gas density giver by Eq.80 3lr.oox6:o)

Thu*, the gas nlir*s mle rntering ths wcll is given hvi:,lJx0,46-t )-- =().01J i mol/nun.t6

Siflee tht nud is biling eirculated at a r:lte rif 3.5i1gallmin, the mol*s ,rf gar per g*ltr:n i:f muri ir givtn hy0.tl&lt/,- -- 00(ru211 rrroli*al_J)t)

Exirnrpl* 4.5 indicates rlrat Ih{ leiss in hydrcsaatic hsrJdus 1r1 nr)mral contarninatii-rn $l thr rtrrilling fluid i* ulual'ly negligible. ln the past this wat nert undetrt*o.l bymany drillirrg pers*nr*l. The c*nfusir:n lvas catrserlrnainty hy * ssvete lorvering af denliity rif the **rilli*gfluid leaving thc w*ll ;it lh* surfirc*. This l*wering ofcl*nsity was due t* the rapirlty expanding tnlrtined gaxn*ulting frorn thc decrcase in hydnrstetie pr*ssur *n thed*lling fluid rs it approached the surlace . 'Ihethesrctical sur{aee mud de,nsity that would Lie seen in fix-ample 4.,5 is given by Eq, 4.1I a:i

I I 4.05? + 1 $10.V&231 )l 14.7I 4.7 "{' r {0.{x}0?.1 1 i{riil. 3.1i6?{ll

=i.9 l1tmild'xl.As r:ne tlrill*r renr*rked, tht* afllouul of l'.rss in nrud den-sity "w*uld rd!r$e. e1,en a mcnkcy t* gct *xcited." ln thcpast, it was eornnr)r1 prit(tice to irrcrtas* the denlrty ulrhe drilling fluicl rvhsn g$r-cut rrturl wus chscrved pn therurlili-c lrccautc rf a fear r:rf a p*tentie] blawcrut,lJowever. fixarlple 4.5 rlearly ghowr that this shr:ultln$t bc dnne unle*s lhe well will fli:w wi{h th* pump rrll.As lhown i* Fig. ;1,5, *igriificln{ decrea$cs in annul*rmud deasity *;cur flnly in the iclrtively slall*w pan af{he rnnulrrs. Thc rapid incre:rle irr trnnultr rle.nxity u'ithrlepth *ccun becaust lhc ga: r'olurrre tlcct*.rst: by a l;lc'tr:r nl'trv* when the .hydnrsurie pryssur (lqxrbl*i. Fur er-arrplr, ine reiiring th* l':ydrn*tatie pm,\ture ;t! th* ,rurlirt*irorn 14"7 tn llf .6 psili r:iruler * unit valunre of gxr tr:dr:crase to c,ne-eighth o{'its original site"

'i #{7 #*:2-S lbrrlSal.


7/9

rFiLL*I.IG I{YSRAilLICS

aLowt tFnfwril!tca&lr{{

agx f.FLfrifll Prft

*P{-L {0{-tit39f nATl (r lrilrruF*A4Yrrf,g Fes|fitftcEtorantofl FLt6

Fg.{rlna{.. H}6X r{gglun 3lnira

A*. 4.f*$chernalic $f we[ eontfol oprelfgn*.{"4 ir"snnlnr Frcssur*s DuringWdl Contral *peratiansSn* *f ilre morc impo*ant applieetians of rhe \rdrostaticpre$sure rdarionxhips is the rletermination sf annq*rpressur*i during w*fi epntrpl epcrati$tts^ Well csarolaperations refer to tha ernergency proccdures fullowdwhen fi$rrnation tluid* b*gir flowlng inro the well andd.ispiaeing the driifing &uid. The ll*w of fomrarion fluidsinto the wcll is cell*d a kclc. A schematic illurrating th*hydraulic flnw parhs dudng well-contrrl operarior:s isihown in Fig. 4.6. Sirnnsrion fluids rhat havi flowed in-kl:he we.llborc generally musr be removed by cireulatingthc well thraugh an adjustable chnke ar rhr: surface. Tl*t{liomho:* prgEsure of the well ar all times trru$t rernainsbave the fr$r$ prassure of thc forrnation lo prevet{ adrli-tiortal inllux cl formatir:n iluid. H*wever, a c$rn*plieati*g factnr is the d*nger of fircturing a wEakerctfftrtffi th*t als,J ir exposed rr: ttrc hydraulic prcssure,Fraettring of an sxpcscd stratum oftcn results in airrrnderground blcw*x*t in slhich aq uncrrntrolled fiqllr *flb'nnsdsn fluids from rhe high-pressure strxrum to thettactt*d strat$rff qcrurs. Thus. rtrc pmycrwe\\ cqurciil:ategy is r* arlio*t a *urfacc choke so rhat the bot-l0mh$l{ prcssurt af tic well is :nrintaincd just slightlyabave the f*rmatrial pr$ssum.A plct of the nrrface annular pre$surs vr. the yalurnettf drilling lhliit circulated is calied an annuiar pre$surepmfile, Althnugh annular pr:ssurc ealeulati*ns iirp nort*r;uired fur well c*ntrnl prncedlrr u**d by nrc*tistlera($rs {etday, a prir:r knawledgc of kirh brhavi*rhelp* in ** gwparatian of appr*priatc contingcnr-ypla:rs. Sincc annular frictisnal pressure lo:$ss arcgener*lly lnrall a! the circutatiag rat*s uii*d in rvell c*n-trcrl opemticns, the calculatians cftn be lrucie. u"ring th*lrydmstat ic prcssrre twttians. :'$,{,4.1 Kich ldcntiflcstionThrl annular presrure praf*rle ilrat wil.t tre obserueJ cluringw*11 csntr,sl $peratian* dcp:nds t$ a large extent on thetomposition uf thc kick fluids. In general. * gas kickeauscs higher annular Fres$ures thii:r a liqrritl kiek. l'hi:iis trur becsu$* a grs kick (l) has a l$wcr densiry d:an rliquid kich aM (2) mu*t be allorved ro npand as ir ispurn;rd [e th purf*ce. Both nf th*se fuctor:l re*ult rn altwer hydn:*tali* pre,ssure in the annulus. T"h*s, to rn;rin

Fig. 4.7*Schsrnatic 'lt i.nilial r,?ll cl)ndilisnc durin0 $ll fantrslapsralion.lain a cr:nsl;nnt traaomhole pressurc, a highcr surlacc an-nular pres.5u6 m!*t k rnaintainerl uuing the arlju*talriechoke.

Kirk compesitir:n nu*t be sp*eified for e*nularpre$surc calculatir:ns made for tlr* purpase r,rf well plan-ning. liick ccarpr:*ition gene:ally ir nct known d*ringactual wll eonrrol trpetxtlii$s. Howev$r, the elen*ity olthe kick fluid can be estimaied fn:rm rhe $bsencddrillpipe prcssurs, annular rasing p$$surc, ad plt gain.Tho density caic*lati


8/9

P. ' 52OopAPpLlf 0 llillLLlFtG EF',lt{rRll\lc

trlnwslt prev{fittr. Ths vqlurne *l tlrr: kii:k'conltr$ifialr'dtonc tan hc cstimrttcd u:ingV u *()+tlt a, i+.20)

Ftutnn!c,J.6. A wclt is hcing 'trilled at u.r'tr:ic:tl dcprlr irfiiii'ii'i *i',';.;;;i;t;;'s a $ o"trrnrsinl nlud ut a.t:ric Llr;.i;br;** whsn ths *tllb"gint to llorr' 'l'wlrrtl barlil; ffi ure gaine{i iri tlx pit ovcr a 3 rninu:,f*tlod**foi* rft* pl*f i* sr*ppcd and th* hlt-rr*cut Pt*\'entcfii;*;il;: Aftcr the'pressutes srabili:'ed' .an init'r*loliroio"- o*tsurc ol 5i0 psig and rrn iniliat casirrg;;i;; Jr ilo p..ii u'c tccutd*J'

rhc annular c'apacitvof thc casing uplxrsrir rncdrillpipc is il'9 ftrbbl' Thc an';;*i"*a.lvlippt'xlt* ft*' lft'ri of r{rili collan.is ?fi'&ruirAl. i-*e-rc ine d*n*ity of lhc- lifk lluid' The tolal*f*"ity of ihe drittstring is 130 bbi'S*[utlnn.Asehenlaticillullr.rtingihegeorrrctr,voltlris"-"*pi- ii giv*n in Fig' 4-8 '}'hc t*ral capaeity opposll*the $ffJ ft nf'd*ll cullzts rl

- gry t -3r 5 bhr.:8.6 it/hhllf it is asrurrrerj thfil lh{ kirk fluiqls en!*reet as a slug' then;;;;; ai kick fluirl rs lers th*n the toial

anlu'larcapacity upg:r:sire rhr' drill collarl' Thus'

Ls,=20 bbl {?8-6 ftlirbli* ?? li'Using 6q. 4.lS' the denslly sf llr* lii{:h niii{i i3 givetr bv

??0- 5l(l,,,. = 9.b -- 1.9 lhmrgul'11 115;1 J7l rTlre rerult{ shoukJ bc int*r1rcted *s ;l* indrcatir:tr rrt lo$-.lcnsrt-v kich f'luitl "Ic ' il 8at - .ll'ir is assunietJ rhat tlrt ir*;k {lui


9/9

DRllltfic ]"tY0ftAtJLtf s$inee the cr.rlumn trl nrixerl ;u*e is *n1y I .*61 Nr !r:ng andund*r lrigh prcssur. the mean d*nsity can be :elared tothe hick {lairl d*nsity u$ing equalieas lor the effecriv**ensity of incornprc$*ible mixtures.

6,{X* ?0ps +?5.5{9,6}45_5$ah,ingi *"ris rqu;ltion ftrr the kick fluid density yicldr

6.Gt{{5.-5) - 9,fii25.5 rPr = --=--:-:--- = I 5 lb'rigal,?flwhieh atser indieais that iie kick fluiql i; rr gar.

Xratnple 4" 7. Again {tcl*sider rhe kick ciescriireri in [r,arnpl* 4.6, Conrpure the nrud densiry requi:tti to hill rhcwell and the cquivalcnt densitl, a( thc caiing se&t fbr rheshut-in r,;ell c*nditions. Alsa cofflpute tire eqtivalcntdensity Ihat w*ulel

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DrBad Drilling Hydraulics