CHAPTER CHAPTER
Cir culation cCir ulation culation culation 14 14 Lost Lost
Introuction Losses of whole mud to subs subsur ur face fac e formations format ions is called lost circulation…
Losses o! "#ole $u to su%sur!ace !or$ations is calle lost circulation or lost returns. Lost circulation #as #istoricall& %een one o! t#e 'r 'ri$ i$ar& ar& contr contri%u i%utors tors to #i(# $u costs. )t#er #ole 'ro%le$s suc# as "ell%ore insta%ilit&* stuc+ 'i'e an even %lo"outs %lo"outs #ave %een t#e result o! lost circulation. ,esies t#e o%vious %ene %e ne!i !its ts o! $ain 'ree$aintaini tainin( n( circulati circulation* on* 'r ventin( or curi curin( n( $u losses is i$'ortant to ot#er rillin( o%ectives suc# as o%tainin( (oo ualit& !or$ation evalue!!ecti ective ve 'ri$ 'ri$ar& ar& ation an ac#ievin( an e!! ce$ent ce$ ent %on on casin(. Lost circulation occurs in one o! t"o %asic "a&s: 1. Invasion or $u loss to !or$ations t#at are cavernous* vu(ular* !racture or unconsoliate. /. racturin( "#ic# is $u loss ue to #&raulic !racturin( !ro$ ecessive inuce 'ressures 2see i(ure 1.
a
d
b
a
d
c
Figure 1: Lost-circulation sections: a: High-permeability unconsolidated sands and gravel. b: Cavernous or vugular zones in carbonates (limestone or dolomite). c: atural !ractures" !aults and transition zones in carbonates or hard shales. d: #nduced !ractures !rom e$cessive pressure.
Lost Cir Lost Cir culation culation culation culation
14.1 14.1
Revision No: Revision Revision No: Revision No: A-0 No:/ Revision A-0 / Revision Date: Date: 03·31·98 03·31·98
Causes o! Lost Cir culation culation 1. Invasion. In $an& cases* lost cir culation cannot %e 'revente in nous* !or$ations t#at are caver nous* vu(ular* !racture or unconsoliate. De'lete lo"-'ressure !or $ations 2usuall& sans are si$ilar relative to lost-circulation 'otential. a. Coarse* unconsoliate !or $ations $ations can #ave su!!icientl& #i(# 'er $e $e- a%ilit& !or "#ole $u to invae t#e !or$at !or$ation ion $atri* resultin( in lost circulation. #is #i(# 'er$ea% 'e r$ea%ilit& ilit& is o!ten 'resent in s#allo" sans an (ravel %es. ee!s or$ations or$ ations t#at "ere once r ee!s an o&ster %es also #ave si$ilar eason tenencies. )ne i$'ortant r eason 'reventin( entin( $u loss in !or 'rev s#allo" intervals is t#at it $a& cause t#es t#ese e unconsoliate unconso liate !or$ations to "as# out* !or$in( a lar(e cavit& t#at is less sta%le "#ic# coul cave
in $ore easil& !ro$ over%ur en en an ri( "ei(#t. %. Anot#er 'otential loss 5one is in e'lete !or$ations 2usuall& sans. 6roucin( !or$ations in t#e sa$e !iel* or (eneral vicinit&* $a& cause su%nor$al 2e'lete !or$ation 'ressure ue to t#e !lu-etraction o! t#e !or$ation !lu is. In suc# a case* $u "ei(#ts reuire to control ot#er e'ose !or$ation 'ressures $a& %e too #i(# !or t#e e'lete !or $ation* $ation* !orcin( $u to invae t#e lo" 'ressure 'ress ure e'lete e'lete !or$ation !or$ation 2see i(ure /. I! t#is situation eists* 'lans s#oul s#oul %e !or$ulate to 'r e- vent lost circulation or stuc+ 'i'e !ro$ occurrin( in t#e e'lete 5one. 7'ecial %ri %ri( (in( in( a(ents an sealin( $aterials s#oul %e us use e to !or$ a (oo seal an !ilter ca+e on t#e e'lete 5one.
%ud &eight 1'.( lb)gal
*roducing &ell
+hale
Limestone
*otential loss zone
+hale
,epleted sand 1. lb)gal
1. lb)gal
Figure ': ,epleted sand.
nous Caver nous or vugular zones zon es ar e usually associated with low-pr essur essur e carbonate…
nous Caver nous and vugular for mations mations are often easily traceable… and edictable… pr edictable…
c. Cavernous or vu(ular 5ones ar e usuall& associate "it# lo"essur e car% 'r essur car%onate onate 2li$ 2li$estone estone an an olo$ite or volcanic !or$ations. In li$e- stone* vu(s are create %& t#e 'r e- vious continuous !lo" o! "ater t#at issolve 'art o! t#e r oc+ 2leac# ac#in(* in(* creatin( a oc+ $atri 2le voi s'ace o!ten later !ille "it# oil. #en t#ese vu(ular !or $ations $ations are rille* t#e rillstrin( $a& !all !reel& t#rou(# t#e voi 5one an a ra'i loss o! $u is usuall& e'e- rience. #e volu$e an 'ersis-- tence o! t#is +in o! loss 'ersis e'ens on t#e e(ree to "#ic# t#e vu(s are interconnecte. 7i$ilar vu(s an caverns can evelo' urin( t#e coolin( o! volcanic $a($a or as#. Cavernous an vu(ular !or $ations are o!ten easil& tracea%le !ro$ o!!set "ells an 'r eicta%le eicta%le !ro$ $u lo(s an lit#olo(& . . u loss also occurs to !issures or !ractures in "ells "#ere no coarsel& 'er$ 'er$ea ea%le %le or cavernous !or $ations $ations eist. #ese !issures or !ractur es es $a& occur naturall&* or $a& %e ini- tiate or etene %& #&raulicall& i$'ose 'ressures. Natu Na tural ral !ra !ract ctur ur es eist in $an& cases* "#ic# $a& %e i$'er$ea%le uner %alance 'r es es- sure conitions. Losses $a& also occur %ounaries. s. at unseale !ault %ounarie /. racturin(. &raulic !racturin( is initiate an lost circulation occurs "#en so$e critical !racture 'ressure is reac#e or eceee. )nce a !ractur e is create or o'ene %& an i$'ose 'ressure* 'res sure* it $a& %e i!!icult to re'air 2#eal an it $a& never re(ain t#e ori(inal ori( inal !or$ation stren(t stren(t#* #* as s#o"n later in i(ure ;. Lost $a& & 'ersist even t#ou(# t#o u(# circulation $a t#e 'ressure is later reuce. #is is one reason "#& %etter ter to 'retreat !or* an it is %et 'r event* event* lost circulation t#an to
'er$it it to occur. Lost circulation resultin( !r o$ o$ inuce 'ressure is usuall& usua ll& caus cause e %& one o! t"o situations:
a. 7ettin( inter$eiate casin( in t#e "ron( 'lace. I! casin( is set a%ove t#e transition 5one crossin( !r o$ nor$al to a%nor$al 'r essur es* t#e 'ressures eerte %& t#e #eav- ier $u 2reuire to %alance t#e increasin( 'ressures "ill o!ten inuce !racturin( at t#e "ea+ cas- in( seat. Losses ue to !racturin( are $ost co$$onl& near t#e 'r e- vious casin( seat* not at %it e't#* even i! casin( is 'ro'erl& set.
%. <cessive o"n#ole 'ressures ar e t#e result o! $an& conitions incluin(: i. ec#anical !or ces. a I$'ro'er #&raulics. <cessive 'u$' rates an velocities causin( #i(# <uivalent Cir culatin( Densit& 2
%ase $us to t#in at #i(#er te$'eratures (enerate "#ile circulatin( an to t#ic+en at lo"er te$'era- tures urin( tri's. It is co$$on !or cir culatin( 'ressures to ecrease 100= 'si as t#e $u #eats to circulatin( te$'eratur e. / Raisin( or lo"erin( t#e 'i'e too !ast 2sur(e/s"a%. c 7'uin( %ri(es. <cessive Rate o! 6enetration 2R)6 !or a (iven !lo" rate "ill result in #i(# cuttin(s concentration in t#e annular !lui causin( a #i(#
ii. ole conitions. a 7lou(#in( s#ale or incr ease solis loain( in t#e annulus an #i(# euivalent circulatin( ensit& . % Accu$ulation o! cuttin(s in a "as#e-out 'ortion o! t#e #ole or in t#e $u. c Cuttin(s %es or %arite sa( !or$in( on t#e lo" sie o! a irectional "ell* or 'ossi%le slu$'in(. ,ri(es. e >ic+s an "ell-contr ol 'r oceur es.
iii. u 'r o'er ties. a <cessive viscosities an (el str en(t#s. % ,uilu' o! rille solis. c #ic+ !ilter ca+es t#at reuce t#e #&raulic ia$eter o! t#e "ell%or e. <cessive $u ensit& or increasin( $u ensit& too !ast. e ?n%alance $u colu$ns. ! ,arite sa(.
6reventive easur es Good planning and pr oper drilling practices are the keys to pr eventing lost cir culation…
/. ini$i5e o"n#ole 'r essur es. a. 6i'e $ove$ent s#oul not ecee critical s'ees "#en tri''in(. #en t#e rillstrin( is run in t#e #ole* t#ere is a sur(in( 'ressure !ro$ t#e 'iston e!!ect o! t#e %it an collars increasin( t#e 'ressure eerte on t#e %otto$ o! t#e #ole. @oo rill- in( 'ractices "ill +ee' t#ese 'r es- sure sur(es "it#in t#e !racture an !or$ation 'ressure* as s#o"n in i(ure 3.
@oo 'lannin( an 'ro'er rillin( 'ractices are t#e +e&s to 'reventin( lost circulation %& $ini$i5in( ecessive 'ressures on t#e !or $ation. 7everal $easures can %e ta+en to 'revent or $ini$i5e lost cir culation: 1. 7et t#e casin( in t#e a''ro'riate 5one so t#e !racture (raient o! t#e !or $a- tion at t#e casin( s#oe "ill %e su! !i- cient to su''ort t#e #&rostatic #ea o! #eavier $us reuire to %alance 'ressures in t#e 3 l !or$ations %elo". a ( / % l 2
t # ( i e " u $ t n e l a v i u . <
1
1;
14
racture 'r essure ,r ea+in( cir culation
Rea$in(
Cir culatin( #ole clean
13 1 Increase in
11 RI
10
Cir c
Drl(
6)) 6ore 'r essure
i$e
Figure : /ottom-hole pressure !or normal drilling cycle (a!ter Clar0).
3 0 0 0 * 1 1 i s ' 2
an& "ells e'erience lost cir culation "#ile runnin( 'i'e or casin( into t#e #ole. #e len(t# o! 'i'e in t#e #ole a!!ects t#e $a(nitue o! t#e sur(e. ests s#o" t#at t#e !lo" o! $u alon( t#e 'i'e creates $ost o! t#e 'r essur e sur(e. #e lon(er t#e 'i'e* t#e (reater t#e sur(e. #ere!ore* t#e ee'er t#e "ell* t#e slo"er t#e
The longer the pipe, the greater the ge sur
!tarting the pumps too rapidly will create a pr essur e that can cause lost cir culation…
e ( r u s
1
1; t # ( i e " 14 u $ t n e l a 13 v i u . < 1/
10
31 B in. 41 B in.
0.4 0. 0 10
/0 30 40 Runnin( s'ee 2sec 'er stan
Figure : 2!!ect o! running speed and annular clearance on pressure sur ges.
,rea+ o"n
Loss o! cir culation
Initial !racture 'r essur e ,r ea+in( cir culation
Rea$in( Re(ain !or$ation str en(t#
Increase in
11
1;*000-!t "ell 8-in. #ole
1.0
e r 0.8 u s s e 0. r 6
'i'e s#oul %e run into t#e #ole as t#e e't# o! t#e %it incr eases. 7$aller annular clearances also increase sur(e 'ressures $uc# in t#e sa$e "a& annular 'r essur e losses are increase as annular clearances ecrease 2see i(ure 4. %. Ra'i $ove$ent o! 'i'e "#ile circulatin( also causes even (reater 'ressure sur(es. Ra'i s'uin( o! t#e 'i'e or !ast rea$in( "#ile circulatin( can create lar(e sur (es. c. Eer& #i(# R)6 loas t#e annulus "it# cuttin(s* t#us increases t#e
1.
RI
6ull
u'
Drl(
Re(aine cir culation ait ill Cir culatin(
#o le #o le clean
6ore 'r essure
i$e
Figure : ,rilling cycle causing !racturing and subse3uent regain o! some !ormation strength (a!ter Clar0).
t#e sur(e is t#e 'ressure reuire to t#e nor$al circulatin( rate. aintainin( lo" (el structure an (rauall& increasin( t#e 'u$' rate "ill reuce t#is t&'e o! sur(e 'r es- sure. ,rea+in( circulation at several intervals "#en tri''in( in #ole is anot#er "a& to $ini$i5e t#ese 'r essur es. e. ?se enou(# rill collars to +ee' t#e neutral 'oint in t#e ,otto$ole Asse$%l& 2,A to $ini$i5e rillstrin( "#i''in(. !. Durin( t#e 'lannin( '#ase o! t#e "ell* casin(s an rillstrin(
esi(n s#oul %e en(ineere !or 'ro'er an sa!e o'eration* an also to o'ti$i5e #&raulics !or (oo #ole cleanin( an $ini$u$
300
De't#: G*000 !t
3 i s ';0 2
103 B 4-in. casin( 41 B -in. rill 'i'e
e ( r u s
00
e r u s s e r 1;0 6
100
;0
0
0
1/ /4 @el stren(t# 2l%/100 !t
3
an restor e 2see i(ure . #e& also
Figure 4: 2!!ect o! gel strength on pressure surge.
increase t#e
'ol&$ers or Lost-Cir culation aterial 2LC. #e use o! LC in t#ese s"ee's is 'r e!er a%le in $an& cases since t#e& are screene out at t#e sur !ace an #ave no 'er$anent e! !ect on t#e viscosit& o! t#e $u. Controllin( t#e R)6 $a& %e necessar& i! e!!icient #ole cleanin( can not %e ac#ieve. Alt#ou(# t#is $a& len(t#en t#e r otatin( #ours* it "ill (enerall& %e less
e'ensive t#an t#e costs incur re %& losin( r eturns. ii. Control rill solis at t#e $ini$u$ 'ractical level an a 'ro'er treat$ent to $ini$i5e !ilter-ca+e %uil-u'. An&t#in( t#at reuces t#e annular clear ance causes a 'ressure incr ease. ,allin( o! t#e %it* collars* sta%ili5ers or tool oints ecr eases t#e annular clearance. In t#e case o! etensive %it an/or sta%ili5er %allin(* a si(ni!icant 'ressure "ill %e eerte on t#e !or$ation. An increase in ra( or s"a%%in( on connections are 'ossi%le inicators o! %allin(. 7o$eti$es a %all can %e 'u$'e o!! a %it* %ut i! t#at !ails* t#e co$$on 'ractice o! s'uin( t#e %it s#oul %e avoie. #e co$%ination o! t#e reuce annular clear ance an t#e 'i'e sur(e can cause t#e 'ressure to ecee t#e !racture 'r essure. iii. i(# !lui-loss $us e'osit a t#ic+ !ilter ca+e t#at can
reuce t#e annular clearance. #e s$aller annular s'ace increases t#e
#en Lost Circulation )ccurs A NALH7I7
The pr obable location of the loss zone may be deter mined fr om knowledge available at the rigsite
) < 6R),L<
#en lost circulation is !irst note* t#e conitions at t#e ti$e t#e loss occurre s#oul %e accuratel& recore an stu- ie. #e ti$e o! t#e occurrence 2"#ile rillin(* circulatin( or tri''in(* t#e t&'e o! t#e loss 2see'in(* 'artial or co$'lete an t#e severit& o! t#e loss "it# r es'ect to t#e e'ose !or$ations s#oul %e consiere. #is in!or$ation "ill #el' eter$ine "#& t#e loss occurre* "#er e in t#e #ole t#e loss occurre an t#e %est re$e& !or t#e situation. #e 'r o%- a%le location o! t#e loss 5one $a& %e eter$ine !ro$ +no"le(e availa%le at t#e ri(site. or ea$'le:
1. or$ation in!or $ation. a. Car%onate !or$ations contain cavernous an vu(ular 5ones. #is t&'e o! loss "oul %e inicate i! t#e loss "as s"i!t* lar (e an acco$'anie %& a ro' in t#e rillstrin(. %. 7#ale !or$ations ten to"ar !rac- turin( t#at $a& %e a slo"er t&'e o! loss. #is loss nees to %e con- trolle uic+l&* as continue losses "ill enlar(e t#e !racture an co$- 'ro$ise !or$ation inte(rit& . c. A c#an(e in t#e rill rate $a& inicate a !or$ation c#an(e "it# 'ossi%le c#an(e in !or $ation inte(rit& .
/. )'erational in!or $ation. a. 7o$e t&'e o! #&raulic-'r essur einuce lost circulation "oul %e inicate i! t#e $u "ei(#t "as %ein( increase at t#e ti$e o! loss. #is t&'e o! loss $a& seal itsel! 2see'a(e or reuire tr eat$ent 2inuce !racture e'enin( on t#e severit& o! t#e loss. %. Ra'i $ove$ent o! t#e rillstrin( "ill cause 'ressure sur(es t#at can inuce !ractures or reo'en 'r eviousl& seale loss 5ones. ?nless a 'reviousl& seale loss 5one #as %een 'ressure teste it s#oul al"a&s %e assu$e t#is area re$ains a 'oten- tial source o! losses. #e rate o! 'i'e $ove$ent urin( tri's an "#ile rea$in( s#oul %e auste to co$'ensate !or t#is "ea+ness. A $ore in!or$e ecision can %e $ae re(arin( t#e 'ro'er ste's to eli$- inate t#e losses "it# t#e in!or $ation (at#ere a%ove.
"estoring cir culation as #uickly as possible is ver y impor tant…
L)CAIN@
< )N<
Restorin( circulation as uic+l& as 'ossi- %le is ver& i$'ortant since lost cir cula- tion increases $u cost an can cause ot#er "ell%ore 'ro%le$s t#at result in aitional o'erational costs. 1. Locate t#e eact 'oint o! lost cir cula- tion. Contrar& to t#e co$$on %elie!* t#e $aorit& o! t#e losses o not occur at t#e %otto$ o! t#e #ole. It #as %een esta%lis#e t#at $ore t#an #al! o! t#e losses occur ust %elo" t#e last casin( s#oe. 7everal $et#os ar e availa%le !or locatin( t#e 'oint o! lost circulation. #ese inclue: a. 7'inner sur ve&. #e s'inner surve& is $ae %& runnin( a s$all s'inner attac# $ent into t#e "ell on a sin(le con- uctor ca%le in suc# a $anner t#at t#e vane rotor "ill s'in or turn i! t#ere is an& #ori5ontal $otion o!
t#e $u. #e R6s o! t#e r otor are recore on !il$ as a series o! as#es or s'aces. #e R6 "ill %e ver& slo" until t#e 'oint o! loss is reac#e. #ere is a e!inite increase in t#e rotorJs s'ee at t#e 'oint o! loss. #ere are t"o o%ections to t#is $et#o: ii. It reuires eli%erate loss o! lar(e volu$es o! $u. ii. It is not e!!ective "#ere sealin( $aterial is alrea& 'resent in t#e $u. %. e$'erature sur ve&. #e te$'erature surve& e'ens on a su%sur!ace t#er$o$eter !or $easurin( t#e i!!erence in t#e $u te$'erature an t#e !or $ation te$'erature. It is $ae %& runnin( a sensitive ele$ent in t#e #ole t#at c#an(es its resistance as t#e te$'erature c#an(es. "o sur ve&s are run. #e !irst is run to esta%lis# t#e te$'erature (raient o! t#e "ell a!ter t#e $u #as co$e to euili%riu$ "it# t#e !or $ation. #e secon surve& is run i$$ei- atel& a!ter ain( !res# cool $u to t#e "ell. A s#ar' te$'eratur e iscre'anc& "ill occur at t#e 'oint o! loss. c. Raioactive tracer sur ve&. Raioactive surve&s !or locatin( t#e 'oint o! loss consist o! $a+in( t"o (a$$a ra& surve&s. A %ase lo( is run %e!ore t#e introuction o! raioactive $aterial. A slu( o! $u containin( raioactive $aterial is t#en 'u$'e o"n t#e #ole an a ne" lo( is run. i(# concentrations o! t#e raioactive $aterial "ill %e locate at t#e 'oint o! loss. #is $et#o 'rovies accurate ata !or locatin( t#e 'oint o! loss* %ut reuires e'ensive eui'$ent an aitional eli%erate loss o! $u to o%tain t#e esire in!or $ation.
. ot "ire sur ve&. #e #ot "ire tool is essentiall& a cali%rate resistance "ire t#at is sensitive to te$'erature c#an(es. It is run to a esire 'oint in t#e #ole an t#e resistance is note. u is t#en 'u$'e into t#e #ole. I! t#e tool is a%ove t#e 'oint o! loss* $u "ill !lo" %& it* c#an(in( t#e r esis- tance. I! t#e resistance oes not c#an(e* t#e tool is %elo" t#e 'oint o! loss. #e tool can %e use in an& +in o! $u* %ut a lar (e a$ount o! $u is reuire "#ile $a+in( t#e sur ve&. e. 6ressure tansucer sur ve&. #is t&'e o! surve& involves usin( a s#ort c&liner o'en at t#e to' an s"a(e at t#e %otto$ to restrict t#e !lo" o! $u t#r ou(# t#e tu%e. A "ino" "it# a neo 'rene ia'#ra($ is !itte on one sie o! t#e tu%e. #ere is an electroe t#at $oves %ac+ an !or t# %et"een t#e t"o !ie electroes on t#e ia'#ra($. As t#e 'r essure i!!erential varies across t#e ia'#ra($* t#e 'otential varies in t#e electric circuit inicatin( t#e rate o! !lo" o! t#e $u an "#ere t#e $u %eco$es static. #is $et#o a''ears to #ave certain avanta(es: K It is si$'le in construction an o'eration. K It is not easil& clo((e %& lostcirculation $aterial. K It is "or+a%le in al$ost an& t&'e o! $u. K It can %e use to locate a #ole insie o! casin(. "o a''arent isavanta(es ar e: K Consiera%le $u !lo" is r euir e. K #e eui'$ent $a& not %e reail& availa%le.
#ou(# it is (oo 'ractice to locate t#e t#ie! 5one* t#ere are several reasons "#& surve&s are not run $ore o!ten: iii. Consiera%le ti$e is s'ent (ettin( t#e necessar& eui'$ent to t#e ri(* an a eli%erate loss o! $u is reuire !or t#ese sur ve&s. iii. #e results o! t#ese surve&s ar e so$eti$es i!!icult to inter'r et. iii. Conitions are not al"a&s suc# t#at t#e tools $a& %e run %ecause o! a%nor$al su%sur!ace 'r essure. /. Deter$ine t#e severit& o! loss. #is is %est eter$ine %& t#e a$ount o! loss an t#e static $u colu$n #ei(#t. I! t#e static $u colu$n #ei(#t is not visi%le it can %e eter $ine %& runnin( a 'iece o! "oo 24 in. 4 in. 4 !t on a "ir eline. Anot#er o'tion is t#e use o! a sonic ec#o-$easurin( evice. a. Loss 5ones can %e classi!ie as: i. 7ee'in( losses 21 to 10 %%l/#r. ii. 6artial losses 210 to ;00 %%l/#r. iii. Co$'lete loss 2#ole !ull to $u level at /00 to ;00 !t. iv. 6artial or co$'lete loss to ee' inuce !ractur es. v. 7evere co$'lete loss 2#ole !ull to $u level at ;00 to 1*000= !t. 3. Deter$ine t#e t&'e o! loss. #is is %est eter$ine %& t#e lit#olo(&. Lost circulation as it relates to lit#olo(& is iscusse a%ove in Causes o! Lost Circulation. #ese classi!ica tions can %e relate to t#e !our t&'es o! !or$ations in "#ic# $u losses occur 2see i(ure 1. a. 7#allo"* unconsoliate !or $a- tions "#ere roc+ 'er$ea%ilit& can ecee 14 arcies 2see a in i(ure 1. Ienti!&in( !eatur es. iii. )!!set recors t#at ienti!& t#e 5one an its c#aracteristics. iii. @raual lo"erin( o! $u level in 'its. iii. Loss $a& %eco$e co$'lete i! rillin( is continue.
%. or$ations t#at #ave natural !ractures suc# as li$estone an so$e #ar s#ale !or$ations 2see c in i(ure 1. Ienti!&in( !eatur es. i. )!!set recors an (eolo(ical $ar+ers. ii. a& occur in an& t&'e o! #ar* %rittle r oc+. iii. Loss is evience %& (raual lo"erin( o! $u in 'its. iv. Loss $a& %eco$e co$'lete i! rillin( is continue an $or e !ractures are e'ose. c. ractures t#at are inuce t#rou(# $ec#anical or #&raulic !orces eerte on t#e !or $ation 2see in i(ure 1. Ienti!&in( !eatur es. i. )!!set recors t#at inclue ecessive annular #&raulics. ii. Coul occur in an& t&'e r oc+* %ut "oul %e e'ecte in !or $ations "it# c#aracteristicall& "ea+ 'lanes* suc# as so!t s#ales. iii. Loss is usuall& suen an co$'lete. iv. Loss $a& !ollo" an& incr ease in $u "ei(#t or suen sur(e in 'r essure. v. Can %e in co$'etent or inco$'etent !or $ations. . Cavernous 5ones nor $all& con!ine to li$estone 2see % in i(ure 1. Ienti!&in( !eatur es. i. Nor$all& con!ine to li$estone an olo$ite. ii. Loss o! returns is usuall& suen an co$'lete.
iii. ,it $a& ro' !ro$ a !e" inc#es to a !e" !eet ust 'recein( loss. iv. <cessive torue $a& %e e'erience %e!ore loss. 4. Classi!ication o! loss %& eter $inin( t#e 'ressure "it#in t#e 5one. a. 6osition t#e %otto$ o! t#e rill 'i'e at t#e to' o! t#e sus'ecte loss 5one. %. Attac# a suita%l& si5e len(t# o! "oo* a''roi$atel& 4-!t lon(* to t#e ri( surve& line an run it o"n t#rou(# t#e rill 'i'e until t#e static !lui level is !oun. A sonic ec#o-$easurin( evice can also %e use to !in t#e !lui level. c. #e 'ressure "it#in t#e loss 5one is t#en calculate as !ollo"s: 65 2D5 - D!2'20.0; $her e% 65 6ressure o! t#e loss 5one 2'si D5 rue Eertical De't# 2ED o! t#e loss 5one 2!t D! lui ro' insie t#e rill 'i'e 2!t ' lui ensit& insie t#e rill 'i'e 2l%/(al . #e static $u ensit& "#ic# t#e 5one "ill su''ort is calculate as !ollo"s: 5 65 20.0; D5 $her e% 5 u "ei(#t t#at t#e 5one "ill su''ort 2l%/(al
Corrective easur es C)RR
) 7
…make an assessment of the sever ity of a loss zone and match the r emedial material and techni#ue to it in ter ms…
#e %est a''roac# to control lost cir culation is to $a+e an assess$ent o! t#e severit& o! a loss 5one an $atc# t#e re$eial $aterial an tec#niue to it in ter$s o! %ot# t#e si5e o! t#e $aterial an its !unction. 1. 7ee'in( losses can occur in an& !or$ation t&'e "#en t#e %ri(in( a(ents are not lar(e enou(# to !or $ a seal 2see i(ure 8a* or "#en t#er e are no !ine 'articles to co$'lete t#e seal. a. #e 'ull-u'-an-"ait tec#niue s#oul %e t#e !irst tec#niue use to atte$'t to re(ain !ull r eturns 2see 'ull-u'-an-"ait tec#niue. %. I! t#e #ole "ill not stan !ull "#ile "aitin(* t#e tec#niue o! $iin( an LC slurr& containin( !ine to $eiu$ %ri(in( a(ents or utili5in( a suee5e #i(#-!ilter-loss slur r& s#oul %e consiere. c. Reuce $u "ei(#t i! 'ossi%le. /. 6artial losses occur in (ravel* s$all natural !ractures an %arel& o'ene inuce !ractures 2see i(ure 1. #e sa$e tec#niues use in see'in( losses s#oul %e use in 'artial losses. a. #e 'ull-u'-an-"ait tec#niue s#oul %e t#e !irst tec#niue use to atte$'t to re(ain !ull r eturns 2see 'ull-u'-an-"ait tec#niue. %. I! t#e #ole "ill not stan !ull "#ile "aitin(* t#e tec#niue o! $iin( an LC slurr& containin( a %len o! $eiu$ to lar(e %ri(in( a(ents or utili5in( a #i(#!ilter loss slur r& suee5e s#oul %e consiere. c. Reuce $u "ei(#t i! 'ossi%le. 3. Co$'lete losses occur to lon(* o'en sections o! (ravel* lon( intervals o! s$all natural !ractures* lar(e natural !ractures or o'en inuce !ractur es 2see i(ure 1.
a. #e 'ull-u'-an-"ait tec#niue s#oul %e t#e !irst tec#niue use to atte$'t to re(ain !ull r eturns 2see 'ull-u'-an-"ait tec#niue. %. ?se #i(#-!ilter-loss slurr& suee5e tec#niue 2see #i(#-!ilter -loss suee5e tec#niue. c. I! returns are not re(aine "it# t#is tec#niue* a #ar 'lu( suc# as a ce$ent* ce$ent-%entonite* ce$ent- (ilsonite or iesel-oil %entonite- ce$ent is reco$$ene 2see tec#niues !or ce$ent slur ries. . Reuce $u "ei(#t i! 'ossi%le. 4. 6artial or co$'lete loss to ee'* inuce !ractur es. a. #e 'ull-u'-an-"ait tec#niue 24 to 8 #r s#oul %e t#e !irst tec#- niue use to atte$'t to re(ain !ull returns 2see 'ull-u'an-"ait tec#niue. %. A''l& so!t 'lu( suee5e 2see tec#niues on so!t 'lu(s. c. I! t#e #ole "ill not stan !ull "#ile "aitin(* t#e tec#niue o! $iin( an LC slurr& containin( a %len o! lar(e %ri(in( a(ents or utili5in( a #i(#-!ilter-loss slur r& suee5e s#oul %e consiere. . Reuce $u "ei(#t i! 'ossi%le. ;. 7evere co$'lete losses occur to lar (e* o'en natural !ractures* caverns an o'en inuce !ractur es. a. 7uee5e "it# eit#er a #i(#-!ilter loss slurr& suee5e or lar(e a$ounts o! iesel-oil-%entonitece$ent slurries 2see tec#niues !or eac#. %. I! t#e severe* co$'lete losses continue to occur as $ore o'en* natural !ractures or caverns ar e 'enetrate* t#e tec#niue o! rillin( %lin or "it# aerate $u an settin( casin( s#oul %e consiere. c. Reuce $u "ei(#t i! 'ossi%le.
CA?7<7
)R AIL?R< ) R<@AIN CIRC?LAI)N
…lostcir culation techni#ues
and materials must be functionally related to the losses they cur e
&ractured shales e'posed to water-base muds will generally heal and cir culation can be r egained…
7o$e o! t#e $ost usual causes* ir ectl& or inirectl&* !or !ailure to control loss o! circulation ar e: 1. #e location o! t#e loss 5one is not esta%lis#e $an& ti$es* resultin( in atte$'ts to 'lace $aterials at t#e "ron( s'ot. Loss 5ones are usuall& not on %otto$ %ut are near t#e last casin( seat or lost-circulation 'oint. /. Lost-circulation $aterials are not s&ste$aticall& $atc#e to t#e t&'e an severit& o! t#e loss 5one. #ere $ust %e a $iture o! 'article si5es to initi ate an 'ro'a(ate an e!!ective seal. 3. #ere is so$eti$es a reluctance to 'rocee to t#e tec#niue reuire to $atc# t#e severit& o! t#e loss 5one 2i.e. rillin( %lin an settin( 'i'e. 4. Aeuate recors are not +e't t#at escri%e t#e losses an t#e $aterials an tec#niues use a(ainst t#e$. Accurate accounts o! e'erience in an area are valua%le. ;. In ce$entin(* t#e colu$ns are not %alance an rillin( $u %r ea+s t#rou(# t#e 'lu( %e!ore it sets. In aition* "#en t#e 'i'e is "it#ra"n !ro$ t#e #ole a!ter 'lace$ent* t#e $u level in t#e annulus (oes o"n an $u !ro$ t#e !or$ation can %rea+ t#rou(# t#e !res#l& 'lace slurr&. ,alance colu$ns an 'lu(- ro''in( tec#niues s#oul %e e$'lo&e. . #e !or$ation stren(t# is too "ea+ to su''ort t#e #&rostatic 'ressure o! t#e !lui colu$n neee to control t#e 'ressure in ot#er e'ose 5ones. o %e e!!ective* t#e lost-circulation tec#niues an $aterials $ust %e !unc- tionall& relate to t#e losses t#e& cur e. or ea$'le* "#ere a reasona%le a$ount 21; to /0 l%/%%l o! LC #as * not "or+e in a #i(#-!ilter-loss slur r& it is usuall& useless to use #i(#er
concentrations o! t#e sa$e or si$ilar $aterials. #e net ste' s#oul %e to increase t#e si5e o! t#e %ri(in( $aterials. ()T*% +t cannot be stressed too str ongly that the lost-circulation techni#ue must be matched to the severity of the loss zone
6?LL-?6-AND-AI
L)7-CIRC?LAI)N A
-I- II<. Cear !i%er 2"oo !i%er. 7a"ust 2"oo !i%er. Drillin( 'a'er 2'a'er. a($a i%er 2$ineral !i%er.
K K K K @ranular K N? 6L?@ 2nut s#ells - !ine* $eiu$ an coarse. K @-7
"i+seal 2%len o! !i%rous* (ranular an !la+es. K -I 7
$u* #ei(#t t#e $u stans in t#e #ole an t#e rate o! loss. #e $ost 'ro%a%le 'oint o! t#e loss is ust %elo" t#e casin( s#oe i! a !racture o! t#e !or$ation ue to a 'ressure sur (e is sus'ecte. /. ?se o'en-ene rill 'i'e !or 'lace$ent o! t#e 'lu( i! 'ractical. )t#er"ise use o'en "atercourse %its or et %its "it# t#e no55les re$ove. I! $aterials $ust %e 'lace t#rou(# a et %it or D/LD tools* $eiu$- to-!ine* si5e %ri(in( a(ents s#oul %e use to 'revent 'lu((in( t#e %it. ()T*% se acid soluble materials for losses to the reservoir 3. i a 100- to ;0-%%l LC slur r& . ,lens o! coarse* $eiu$ an !ine (ranular* !i%er an !la+e %ri(in( a(ents are co$$erciall& availa%le an coul %e su%stitute !or t#ose ae se'aratel&. ?se $u !r o$ t#e circulatin( s&ste$ or $i LC in a !res#l& 're'are* viscous*
R
K i(#-!ilter-loss suee5e 27alt (el O A ; l%/%%l coarse-to-$eiu$
iato$aceous ear t#. !i%ers. K Ce$ent slurr& 2#ar 'lu(. material )il-%ase suee5es must be K Diato$aceous ear t#. tailored to K Calciu$ car%onate O -I-<. K @un+ suee5e !or oil $us 2E@-94 the severity in "ater. of loss…
?7<
) 6L?@@IN@ )R ,RID@IN@ A@
#is tec#niue s#oul %e use a(ainst see'in( an 'artial losses an t#e less severe co$'lete losses. A 'lu( o! %ri(in( a(ents in t#e $u is $ie an a''lie as !ollo"s: 1.
t#e
seldom known This logic is based on the knowledge that low rates of loss occur through small openings and higher rates of loss occur through larger openings &igure illustrates how materials that are too large will form a bridge at the face of the open- ing, while properly sized materials form a bridge in the opening where it is not as likely to be eroded away when circulation is resumed &igure . illustrates how the use of materials that are too small go through the opening and do not form a bridge $hen selecting the size of materials to use, the size of the nozzles in the bit and other pos- sible restrictions /eg 0$1 tools, mud motors2 should always be consider ed
5
/
5
Figure 6a: Fracture seal at !ace o! &ellbor e. Figure 6b: Fracture seal &ithin the !ormation.
/
3 Figure 7a: +mall lost-circulation materials !ailing to l % % a bridge. Figure 7b: #nitial bridge being !ormed by / !orm % l 2large particle &ith !inal seal by smaller par ticles. n o i t a A t&'ical A t&'ical r t n 1 !i%r ous la$ellate e c $aterial $aterial n 1 o C
o'en-ene rill 'i'e o''osite t#e loss 5one. 6u$' at a slo" rate until t#e $aterials #ave sto''e t#e loss. Re'eat once $ore i! t#e #ole oes not A t&'ical 8 !ill an t#en 'rocee to a #i(#-!ilter(ranular $aterial 4 loss slurr& suee5e tec#niue* i! t#er e 0 still is no inication o! success. I! t#e 0 .0/ .04 .0 .08 .10 .1/ .14 .1 .18 .0 Lar(est !racture seale 2in. #ole !ills* close t#e %lo"out 'r eventers Figure 8: 2!!ect o! concentration and type o! 2ra$s an suee5e t#e annulus "it# lost-circulation material on sealing !ractur es ;0 'si !or 30 $in. easure t#e (a!ter Ho&ard and +cott). 'r es- sure on t#e annulus usin( a trou%le an 'oor $u 'ro'erties $a& 0- to result !ro$ #i(#er concentrations. 300-'si (au(e. LC slurries o"ever* i! %ri(in( a(ents are to containin( a %len o! $aterials are %e a''lie in a slu( o! $u* t#en $ost e!!ec- tive. ,ri(in( a(ents con- centrations u' to 30 l%/%%l can $ust contain at least (ranular an %e $ore e!!ective 2see a%les 1 an !i%rous a(ents to %e e!!ective. A . use!ul LC $iture is It is i$'ortant to increase t#e si5e 3 to 'arts (ranular* / 'arts an a$ount o! t#e (ranular a(ent i! !i%r ous an 1 'art !la+e $aterial. conventionall&-si5e $aterials are not #e si5e o! t#e (ranular an !la+e e!!ective. #e e!!ectiveness o! (ranular * %ri(in( a(ents s#oul %e $atc#e to !i%rous an !la+e %ri(in( a(ents in t#e severit& o! t#e loss. No avanta(e 'lu((in( a si$ulate !racture is s#o"n is (aine i! t#e concentration o! lostin i(ure 9. circulation $aterials in t#e total $u s&ste$ or #i(#-!ilter loss slurr& ecees 1; to /0 l%/%%l 2see i(ure 9. 6u$' 7tatic 7lot
Concentration 2l%/%%l
Lar(est 7lot 7eale 2in.
ar%le ,e
Eolu$e #r u at 1*000 'si 2$l
Eolu$e #r u at 1*000 'si 2$l
,,-7#ot ,e
7eal
Eolu$e #r u at 1*000 'si 2$l
7eal
10
0.10
;00
All
No
1*G00
Hes
0
0.13
;0
1*900
Hes
*0;0
Hes
30
0.1
400
1*G00
Hes
800
Hes
40
0.0
300
1*G00
Hes
1*800
Hes
9able 1: *er!ormance o! various concentrations o! mi$ed sealing materials (a!ter Lummus).
l%/%%l Coarse@rin aterial
30 est
1
6u$'in( test t#rou(# 9 B 3-in. stanar et %it no55les
3
4
6lu((e i$$eiatel&
lo"e t#r ou(# at /00 'si
7tatic slot: Lar(est slot seale 2in.
0.1
0.08
otal vol t#rou(# 2$l
400
100
D&na$ic slot: Lar(est slot seale 2in.
0.13
0.0
otal vol t#rou(# 2$l
00
0.;0
7tatic $ar%le %e: Eol t#rou(# at 100 'si 2$l
;00
400
1*G00
1*00
,,-s#ot %e: Eol t#rou(# at 100 'si 2$l
400
300
Eol t#rou(# at 1*000 'si 2$l
800
800
Eol t#rou(# at 1*000 'si 2$l ;
&or a bridging agent to function, some of it must be of suf ficient size to bridge the opening to be plugged
l%/%%l eiu$@rin aterial
30
9able ': Comparison o! coarse and medium grinds o! mi$ed sealing material in mud (a!ter Lummus). u losses ran(in( in severit& !r o$ sti$ulation inustr& t#is is calle !rac1 1 ture-ti' screen out. luis treate see's to co$'lete losses into B 8- to B 4"it# in. natural an inuce !ractures can 1; to 30 l%/%%l o! $aterial #avin( a %e sto''e %& usin( %ri(in( a(ents. 'ar - ticle si5e si$ilar to $eiu$ an or a %ri(in( a(ent to !unction* so$e coarse N? 6L?@* @-7
aterial
&'e
Descri'tion
Concentration 2l%/%%l
Lar(est racture 7eale 2in. 0
3
Nut s#ell
@ranular
;0F P B 1= 10 $es# ;0F P 10= 100 $es#
0
6lastic
@ranular
;0F P 3 B 1= 10 $es# ;0F P 10= 100 $es#
0
Li$estone
@ranular
;0F P 3 B 1= 10 $es# ;0F P 10= 100 $es#
40
7ul'#ur
@ranular
;0F P 3 B 1= 10 $es# ;0F P 10= 100 $es#
10
Nut s#ell
@ranular
;0F P 10= 1 $es# ;0F P 30= 100 $es#
0
<'ane 'erlite
@ranular
;0F P 3 B 1= 10 $es# ;0F P 10= 100 $es#
0
Cello'#ane
3
La$ellate
B 4-in.
7a"ust
i%r ous
6rairie #a&
i%r ous
1
i%r ous
3
,ar+
Cotton see #ulls 6rairie #a&
Cello'#ane 7#ree "oo 7a"ust
B 4-in. 'ar ticles B -in. B 8-in.
@ranular i%r ous
!la+es
1
10
!i%ers
10 10
B 8-in. 'ar ticles
1
La$ellate
1
!la+es
8
i%r ous
1
!i%ers
8
i%r ous
B 4-in.
1
B 1-in. 'ar ticles
.1/
.1
.0
8
ine B -in.
.08
10
!i%ers
3
.04
0
Figure 1: +ummary o! lost-circulation material tests (a!ter Ho&ard and +cott).
is thr ough filtration that the
+t
lostcir culation materials and mud solids ar e left as a firm plug in the opening taking mud
I@-IL
:ater
Figure 11: High-!luid-loss-s3ueeze techni3ue !or lost circulation sho&ing &ater being lost through !iltration depositing solids &ithin !ractur e.
o! #i(#-!ilter-loss slurries an t#eir a''li- cation to loss 5ones var&in( in severit& !ro$ see'in( to 'artial to co$'lete ar e escri%e later . #ere are sli(#t i!!erences in a''lication to t#ese 5ones* %ut t#e $ain is- tinction is increasin( t#e si5e o! t#e %ri(in( a(ent as t#e loss 5one %eco$es $ore sever e.
+f hydraulic fracturing of the formation is suspected, the most pr obable point of loss is :ust below the casing shoe
To avoid fracturing other zones, safe s#ueeze pr essur es in e'cess of mud hydrostatic pr essur e should be used
irst* t#e severit& o! t#e loss s#oul %e esta%lis#e !ro$ t#e !lui level an t#e rate o! loss. #en* t#e a''r oi$ate 'oint o! t#e loss s#oul %e esta%lis#e an t#e t&'e o! !or$ation ta+in( $u e!ine. I! #&raulic !racturin( o! t#e !or$ation is sus'ecte* t#e $ost 'r o%- a%le 'oint o! loss is ust %elo" t#e casin( s#oe.
)R
7<<6IN@ L)77
1. i 100 %%l o! slur r& : a. A 10 to /0 l%/%%l o! atta'ul(ite or se'iolite cla& to 80 %%l o! "ater 2atta'ul(ite an se'iolite cla&s %e#ave si$ilarl& in salt"ater. I! t#ese cla&s are not availa%le* use ; to /0 l%/%%l %entonite an 'r etreat t#e "ater1 "it# 1 B 4 l%/%%l o! soa as# an B 4 l%/%%l o! caustic soa to re$ove calciu$ an $a( nesiu$ ions. Allo" cla& to &iel. I! %entonite is use* a 1 B l%/%%l o! li$e to !locculate t#e %entonite an increase t#e !lui loss. or: %. A ;0 l%/%%l o! iato$aceous eart# $aterials 2Diaceel D* Diaseal or a suita%le su%stitute suc# as L)-A<<. Diaseal is a $iture o! iato$aceous ear t#* li$e an 'a'er. I! t#is $iture is use* atta'ul(ite is not reuire. A i!!erent LC si5es an s#a'es to o%tain a 10- to 0-l%/%%l total concentration o! LC. /. 7et t#e %it at t#e to' o!* or o''osite* t#e loss 5one. Dis'lace t#e LC slurr& to t#e en o! t#e rill 'i'e. 3. Close t#e ra$s. @entl& suee5e 2;0 'si $ai$u$ $aterial into t#e loss 5one at a rate o! 1 %%l/$in. ol t#e suee5e 'ressure 4 to 8 #r or until it issi'ates. easure t#e suee5e 'ressure on t#e annulus usin( a 0- to 300-'si (au(e.
o avoi !racturin( ot#er 5ones* sa!e suee5e 'ressures in ecess o! $u #&rostatic 'ressure s#oul %e use. or ea$'le: De't# 2!t 0 - 1*000 1*000 - ;*000
;*000 an ee'er
7uee5e 6ressure 2'si 0 - 00 100 - ;00 ;00
()T*% !urface pressure plus mudcolumn pressure should never e'ceed overburden pressure /; psi8ft2
)R
6ARIAL L)77
1. i 100 %%l o! slur r& : A 10 to /0 l%/%%l o! atta'ul(ite or se'iolite cla& to 80 %%l o! "ater . I! t#ese cla&s are not availa%le an %entonite is use as t#e viscosi!ier * a 1 B l%/%%l o! li$e to !locculate t#e cla&s an increase t#e !lui loss. or: A ;0 l%/%%l o! iato$aceous eart# $aterials 2as %e!ore or a suita%le su%stitute 2L)-A<. ?se %arite onl& i! t#e $u "ei(#t is 1/ l%/(al or #i(#er or i! it is t#e onl& iner t 'o"ere $aterial availa%le. A a co$%ination o! i!!erent LC si5es an s#a'es to o%tain a 1;-l%/%%l total concentration o! LC. /. 7et t#e rill 'i'e "it# t#e o'en en at t#e to' o! or o''osite t#e loss 5one. 3. Dis'lace /; %%l o! slurr& into t#e 5one at a rate o! / to 4 %%l/$in. 4. 7#ut o"n !or /0 to 30 $in. ;. Dis'lace anot#er /; %%l o! slurr& at t#e sa$e rate. . Continue t#is 'roceure* alter natel& "aitin( an is'lacin( until t#e #ole !ills. 7o$eti$es t"o 100-%%l %atc#es "ill %e reuire. #e rill 'i'e s#oul %e reci'rocate urin( t#ese o'era- tions to 'revent it !ro$ stic+in(.
G. #en t#e #ole !ills* close t#e ra$s an suee5e t#e annulus "it# ;0 to 100 'si %& is'lacin( t#e slurr& ver& slo"l& 21 %%l/$in o"n t#e rill 'i'e. Attac# a 0- to 300-'si (au(e to t#e annulus so t#at lo" 'r essure values can %e easil& rea. aintain t#e suee5e !or 30 to 0 $in. 8. 6ull out o! t#e #ole* 'ic+ u' t#e %it an continue rillin(.
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C)6L<< L)77
#e 'roceure !or co$'lete loss is t#e sa$e as t#e 'roceure !or 'artial loss ece't !or t#e co$'osition o! t#e %ri(- in( a(ents. #e co$'osition o! t#ese $aterials s#oul %e as !ollo"s: 1. A 10 to 1; l%/%%l o! atta'ul(ite or se'iolite cla& to 80 %%l o! "ater. I! t#ese cla&s are not availa%le* treat
t#e "ater as %e!ore. A 1 B l%/%%l o! li$e. or: A ;0 l%/%%l o! iato$aceous eart# $aterials 2as %e!ore. ?se %arite onl& i! t#e $u "ei(#t is 1/ l%/(al or #i(#er or i! it is t#e onl& iner t 'o"ere $aterial availa%le. A a co$%ination o! i!!erent LC si5es an s#a'es to o%tain a /0- to 30-l%/%%l total concentration o! LC. or is'lace$ent* see 7te's t#rou(# 8 in or 'artial loss. /. #en severe* co$'lete loss r eturns occur in !or$ations "it# lar(e* naturall& occurrin( !ractures* vu(s* c#annels or cavernsQ at least one conventional lost-circulation 'ill suc# as t#ose 'reviousl& iscusse s#oul %e s'otte. I! t#is 'r oceur e !ails to i$'rove t#e lost-cir culation 'ro%le$* cavern treat$ents "it# %ul+ !illers suc# as ra(s* $u sac+s*
#a&* 'a'er* "oo* etc. s#oul %e consiere 'rior to 'u$'in( ce$ent 'lu(s.
ARD
6L?@7
Earious #ar ce$ent 'lu(s are o!ten e!!ective a(ainst co$'lete losses an severe co$'lete losses. #e co$'osition an tec#niue o! a''lication o! t#e ce$ent slurr& %ein( use to co$%at lost circulation $ust %e !unctionall& aeuate i! t#e o% is to succee. 1. Ce$ent slurr& co$'osition. Ce$ent* or ce$ent 'lus %entonite* is an i$'ortant lost-cir culation re$e& %ecause t#ese slurries "ill o!ten seal vu(ular loss 5ones. #ree 6ortlan ce$ent slur ries are reco$$ene: neat* %entonite
an (ilsonite. #ese #ave %een c#osen %ecause a "ie variet& o! 'ro' erties can %e o%taine an t#e& ar e usuall& availa%le.
Neat-6ortlan ce$ent. i to 1;. l%/(al usin( 4F "ater an ce$ent. #is slurr& is a ense !lui an evelo's #i(#-co$'r essive stren(t# "#en it sets. ,entonite or (el ce$ent. ,entonite ce$ent !or$e %& ain( ce$ent to "ater containin( 're#&rate %en tonite (ives o'ti$u$ 'ro'erties. #e slurr& !or$e #as lo"er ensit& an #i(#er (el stren(t#. It also #as a #i(#er set stren(t# t#an a slur r& !or$e %& ain( "ater to a r & $iture o! %entonite an ce$ent. In $iin( t#e slurr&* treat t#e !res#"ater to %e use "it# 1 B 4 l%/%%l o! soa as# an 1 B 4 l%/%%l o! caustic to re$ove calciu$ an $a(nesiu$
ions. A 10 l%/%%l o! %entonite an allo" t#is to &iel. ?se t#is %entonite slurr& to $i a 14.; to 1;.0 l%/(al %entonite-ce$ent . ?se 100 sac+s o! ce$ent or slur r& $or e !or lar(e #ole si5es.
@ilsonite-6ortlan ce$ent. @ilsonite can %e ae to ce$ent slurries t#at are %ein( use to re(ain returns. It ecreases t#e ensit& o! t#e slur r & an acts as a %ri(in( a(ent* %ot# o! "#ic# #el' to +ee' t#e slurr& in t#e vicinit& o! t#e "ell%ore. It s#oul %e run eactl& li+e %entonite-ce$ent slurries an s#oul %e suee5e i! t#e #ole !ills urin( its a''lication. ,et"een /; to 100 l% o! (ilsonite 'er sac+ o! ce$ent are r eco$$ene. #ese t#ree ce$ents are reco$$ene %ecause t#e& 'rovie slur ries "it# a ran(e o! 'ro'erties !r o$ t#in* #eav& slurries t#at set #ar* to li(#ter* t#ic+ slurries #avin( %ri(in( 'ro'erties. #e& are also availa%le ever&"#ere. o"ever* t#e& are not intene to %e use to t#e eclusion o! all ot#er ce$ent !or $ulations. 1. ec#niues !or a''l&in( ce$ent. Ce$ent slurries s#oul %e use to co$%at losses to natural !ractur es 1 B 3 in. to 1 !t in ia$eter* an to %ro+en li$estones or %oulers. ()T*% Cementing loss zones fails many times because mud has broken through the unset slurry =>alancing columns? will usu- ally prevent this, particularly if column weights are carefully calculated
,ALANC
3. C#oose a ce$ent slurr&. Accor in( to t#e severit& o! t#e loss 5one* $i an run 100 to 300 sac+s. 4. Locate t#e loss 5one* usin( an a''ro'riate tec#niue escri%e 'r eviousl&. ;. Run t#e rill 'i'e an ce$entin( su% 'ast t#e loss 5one to $a+e sur e it is e'ose. Clean t#e #ole 'ast t#e 5one i! reuire. 6ull u' t#e ce$entin( su% at a 'oint ;0 !t a%ove t#e to' o! t#e loss 5one. . Calculate t#e slurr& volu$e o! ce$ent neee to %e s'otte. i an 'u$' t#e ce$ent until t#e esire volu$e is 'u$'e. Dis'lace t#e rill 'i'e at 10 %%l/$in. Leave enou(# ce$ent insie t#e rillstrin( to %alance t#e 'lu( in t#e annulus. #is "ill eli$inate t#e ?-tu%e e!!ect an $ini$i5e ce$ent conta$ination. G. 7lo"l& 'ull out o! t#e #ole. As t#e 'i'e is "it#ra"n* t#e $u level in t#e annulus "ill !all an cause an i$%alance o! 'ressure !ro$ t#e !or $ation to t#e #ole. #is $a& cause $u or !or$ation !luis to %r ea+ t#rou(# t#e ce$ent slurr&. o 'r event t#is* ver& care!ull& a $u to t#e annulus t#rou(# t#e !ill-u' line. Ain( too $uc# $u to t#e annulus "ill !orce $u !ro$ t#e annulus into t#e !or$ation t#r ou(# t#e ce$ent slurr& %e!ore it #as a c#ance to set. #e a$ount o! $u 'u$'e $ust $atc# t#e volu$e is- 'lace$ent 2not ca'acit& o! t#e 'i'e. I! it is one carelessl&* it can o $or e #ar$ t#an (oo. 6u$' t#e reuire a$ount o! $u ever& 10 stans. ait on ce$ent at least 8 #r . 8. easure !lui level. I! it is lo"er or #i(#er t#an t#e ori(inal static level* o not atte$'t to aust. I! it is #i(#er an anot#er 'lu( is r un* aust %& ain( 'ro'ortionatel& less $u as t#e 'i'e is "it#ra"n.
DI<7
?se t#is tec#niue a(ainst co$'lete losses an severe co$'lete losses. #ese ste's s#oul %e use in a''l&in( t#is tec#niue: 11. I! 'ossi%le* rill "it#out r eturns t#rou(# t#e entire lost-cir culation 5one. 1/. 6ull out o! t#e #ole. easure static $u level as 'reviousl& $entione. 13. Locate t#e loss 5one as in 7te' 4* %alance-colu$n $et#o. 14. A!ter locatin( t#e loss inter val* set t#e %otto$ o! t#e $iin( su% ;0 !t a%ove it. 7et a $ai$u$ suee5e 'r essure. 1;. 6u$' in a 10-%%l cus#ion o! "ater -!r ee iesel oil a#ea o! . t#e slur r& 1. i 100 sac+s o! re(ular ce$ent an 100 sac+s o! %entonite "it# ;0 %%l o! iesel oil. or volu$es ot#er t#an ;0 %%l* $i t"o* 9-l% sac+s o! ce$ent an t"o* 100-l% sac+s o! %entonite "it# eac# %ar re l o! iesel oil. or lar(e !ractures or lon( sections o! #one&co$%e vu(s* 300 sac+s o! eac# $aterial s#oul %e use. or lar(e %atc#es* use a ce$enter an $i t#e r& $aterials "it# t#e iesel oil continuousl&. or s$all %atc#es use a suita%le tan+. #is $iture "ill &iel 1.39 %%l o! !or eac# %arrel o! iesel oil. slur r& #is slurr& "ill "ei(# 11.; l%/(al. 1G. Dis'lace t#e slurr& o"n t#e rill 'i'e an !ollo" it "it# ; %%l o! iesel oil. 18. 7tart 'u$'in( rillin( $u into t#e annulus "#en t#e 10-%%l cus# ion o! iesel oil reac#es t#e $iin( su%. Close t#e ra$s. Control t#e 'u$'in( rates so t#e ratio o! t#e slurr& volu$e to t#e $u volu$e
is /:1. 6u$' rates o! 4 %%l/$in o"n t#e rill 'i'e an / %%l/$in o"n t#e annulus "ill usuall& %e satis!actor& "it# 41 B -in. rill 'i'e in GG B 8-in. an lar(er #oles. 19. Dis'lace one-#al! o! t#e slurr& into t#e !or$ation at t#is !ast 'u$'in( rate. #e rill 'i'e $a& occasionall& %e reci'rocate slo"l& to inicate "#et#er t#e slurr& $i(#t %e $ovin( u' t#e annulus. I! t#e "ei(#t inica - tor s#o"s an& increase ra(* %r ea+ t#e connections an raise t#e 'i'e until it is !ree. a+e connections an continue is'lace$ent. #er e is no nee !or concern over s#or t s#uto"n 'erios since t#e slur r& #as no 'u$'in( ti$e li$itation insie t#e 'i'e. 10. Dis'lace t#e net uarter o! volu$e o! slurr& an $u at one-#al! t#e rate use in 7te' 9. 11. Dis'lace t#e re$ainin( uarter volu$e o! slurr& at one-#al! o! t#e rates use in 7te' 10. I! t#e #ole !ills* as s#o"n %& 'ressure on t#e annulus* atte$'t 2%& a #esitation suee5e to o%tain a 'r essur e %uilu' usin( rates o! 1 %%l/$in into rill 'i'e an 0.; %%l/$in into annulus. ()T*% )ne barrel of slurry should be left in the drill pipe at the completion of the s#ueeze, if pressure has developed >alance columns if no pressure develops 1o not attempt to reverse circulate because mud will contact the slurry and gel up inside the drill pipe 1/. A!ter t#e suee5e o%* 'ull out o! t#e #ole an "ait a $ini$u$ o! 8 #r !or t#e ce$ent to set %e!ore rillin( out. I! t#e !irst atte$'t is unsuc- cess!ul* re'eat t#e 'roceure a!ter "aitin( on t#e ce$ent !or 8 #r .
3void contamination of the slur r y with mud or water in the suction lines and pumps
6R
7)
The success of downholemi'ed soft plugs depends on having the right amount of components meet and mi' near the loss zone
6L?@7
Do"n#ole-$ie so!t 'lu(s 2iesel-oil/ %entonite* ,en(u$. ?se t#is tec#niue a(ainst inuce !ractures an to #ol ce$ent slurries at or near t#e "ell%or e until t#e& set. #e success o! o"n#ole-$ie so!t 'lu(s e'ens on #avin( t#e ri(#t a$ount o! co$'onents $eet an $i near t#e loss 5one. Close attention s#oul %e 'ai to t#is. or ea$'le* in usin( iesel-oil/ %entonite* $u can %e 'u$'e into t#e annulus to esta%lis# t#e o'ti$u$ constant $u!lo" rate %e!ore t#e iesel-oil/%entonite slurr& leaves t#e rill 'i'e. o" to $i an a''l& iesel-oil/%entonite: 11. I! 'ossi%le* rill "it#out r eturns t#rou(# t#e entire lost-cir culation 5one.
1/. 6ull out o! t#e #ole. easure t#e static $u level as 'r eviousl& escri%e. 13. Locate t#e loss 5one as 'r eviousl& escri%e. 14. A!ter locatin( t#e loss interval* r un t#e 'lace$ent su% 'ast t#e loss 5one to $a+e sure it is e'ose. 6lace t#e %otto$ o! t#e $iin( su% ;0 !t a%ove it. 7et a $ai$u$ suee5e 'r essure. 1;. 6u$' in a 10-%%l cus#ion o! "ater !ree iesel oil a#ea o! t#e slur r& . 1. i /00* 100-l% sac+s o! %entonite "it# ;0 %%l o! iesel oil. or volu$es o! ot#er si5es* $i 4 sac+s o! %entonite "it# eac# %arrel o! iesel oil. iin( can %e one continu- ousl& usin( a ce$entin( truc+. #is $iture "ill &iel 1.39 %%l o! slur r& !or eac# %arrel o! iesel oil. or severe loss 5ones* 00 sac+s o! %en- tonite in 1;0 %%l o! iesel oil $ie continuousl& s#oul %e use. 1G. Dis'lace t#e slurr& o"n t#e rill 'i'e an !ollo" "it# ; %%l o! iesel oil. #en t#e !ront o! t#e 10-%%l iesel oil cus#ion reac#es t#e en o! t#e rill 'i'e* %e(in 'u$'in( rillin( $u into t#e annulus at a rate o! 4 %%l/$in "it# a secon 'u$'. Close t#e ra$s. 18. Control t#e 'u$'in( rates so t#at t#e ratio o! slurr& volu$e to $u volu$e is 1:1. 6u$' rates o! 4 %%l/$in o"n t#e rill 'i'e an 4 %%l/$in o"n t#e annulus "ill usuall& %e satis!actor& "it# 41 B -in. rill 'i'e in GG B 8-in. an lar(er #oles. 19. Dis'lace one-#al! o! t#e slurr& into t#e !or$ation at t#is !ast 'u$'in( rate or until 'ressure %e(ins to %uil u' on t#e annulus. #en 'r essur e is o%taine* slo" t#e 'u$' rate on %ot# t#e rill 'i'e an annulus to (et t#e slurr& into t#e loss 5one "it#out eceein( t#e $ai$u$
'ressure set 2100 to ;00 'si. Attac#
These pills may also be used to pr event water flow and consolidate loose gravels
a 0- to 300-'si (au(e to t#e annulus so t#at lo"-'ressure values can %e easil& rea. #e rill 'i'e $a& occasionall& %e reci'rocate slo"l& to o%tain an inication as to "#et#er t#e slur r& $i(#t %e $ovin( u' t#e annulus. I! t#e "ei(#t inicator s#o"s an& increase ra(* %rea+ t#e connections an raise t#e 'i'e until it is !ree. a+e connections an continue is'lace$ent. #ere is no nee !or concern over t#e s#or t s#uto"n 'erios since t#e slur r& #as no 'u$'in( ti$e li$itation insie t#e 'i'e. 10. Dis'lace t#e net uarter o! slur r& volu$e an $u at one-#al! t#e rate use in 7te' 9. 11. Dis'lace all ece't 1 %%l o! t#e re$ainin( uarter volu$e o! slur r& at a rate o! one-#al! t#e rate use in 7te' 10. Atte$'t* %& a #esitation suee5e* to (et a 'ressure %uilu'. ()T*% )ne barrel of slurry should be left in the drill pipe at the completion of the s#ueeze 1o not attempt to reverse circulate because mud will contact the slurry and gel up inside the drill pipe 1/. In instances "#ere t#e #ole cannot %e !ille* a 'ac+er s#oul %e set in t#e %otto$ o! t#e casin(. u an slurries s#oul %e is'lace o"n t#e rill 'i'e in alternate %atc#es o! /0 %%l o! slurr& to ; %%l o! $u usin( a s'acer o! 1 or / %%l o! oil %et"een slur ries. 13. A!ter t#e suee5e o%* 'ull out o! t#e #ole !or t#e %it* rill out t#e 'lu( an t#en rill a#ea. Re'eat t#e 'roceure i! no suee5e 'ressure evelo's. @"*C3T+)(!% )bserve the same pre- cautions mentioned previously for the diesel-oil8bentonite8cement slurry s#ueeze
) ) ,
I AND A66LH A 7M?<<<
alli%urton ,en(u$ No. 1 is a natural (uar (u$ 'lus a 'reservative an a co$- 'letin( a(ent. ,en(u$ $i is a 10 "t F ,en(u$ No. 1 an 90 "t F %entonite 're$ie to(et#er . ,en(u$ slurr& is 're'are %& ain( 100 l% o! ,en(u$-%entonite $i to 13 to 1; (al o! iesel oil. It sets #ar er t#an iesel-oil/%entonite %ecause o! t#e or(anics it contains* 'articularl& "#en $ie in saline "aters an $us. Its set stren(t# !alls %et"een t#at o! iesel-oil/ %entonite an iesel-oil/%entonite/ ce$ent %ut is $ore nearl& li+e ieseloil/ %entonite. It s#oul %e use: K #ere $ore stren(t# t#an t#at (iven %& iesel-oil/%entonite is r euire. K #ere saline $iin( "aters are si(ni!icantl& lo"erin( t#e stren(t# o! iesel-oil/%entonite. or a''lication* !ollo" t#e instructions !or iesel-oil/ %entonite a%ove. #e r eco$$ene ratio o! $u to ,en(u$ varies !r o$ 4:1 to 1:1 accorin( to t#e str en(t# reuire.
CR)77LIN>
$aterials or %e iniviuall& 'ac+a(e. ost o!!er a retarer an accelerator !or s'eci!ic cases i! neee. In $ost situations* t#e retarer "ill %e reuire to ela& 're$ature crosslin+in( until t#e slurr& can %e 'lace o''osite t#e loss 5one. #e 'ills $a& %e "ei(#te "it# -I ,AR or
slurr& to t#e rill 'i'e an is'lace t#e slurr& !ro$ t#e %it* 'ull u' an suee5e t#e 'ill. 6ilot testin( is #i(#l& r eco$$ene to eter$ine t#e correct concentration o! retarer or accelerator to %e use. &'icall&* t#e 'ills "ill reac# consistenc& at 11;S 24SC in a''r oi$atel& 0 $in "it# no retarer or accelerator use. #e crosslin+in( is !aster at #i(#er te$'eratures. #ere!ore* in $ost situa- tions a retarer "ill %e neee. A(ain* consult t#e $anu!acturersJ r eco$$en- ations to avoi 're$ature setu' o! t#e 'ill.
DRILLIN@ ,LIND/ A
ec#niues !or reatin( Lost Circulation in )il-,ase us
$ ater -
base fluids typically have a higher =spur t? fluid loss causing an almost instantaneous filter cake…
Alt#ou(# t#ere s#oul %e no i! !er ence %et"een "ater- an oil-%ase $us in t#e 'ressure neee to initiate a #&raulic !racturin( o! t#e !or$ation* t#ere is a si(ni!icant i!!erence once t#e !ractur es are !or$e. ater-%ase !luis t&'icall& #ave a #i(#er s'urt !lui loss causin( an al$ost instantaneous !ilter ca+e to !or$ t#at ais in !or$ation sealin( in 'er$ea%le !or $ations. )il-%ase !luis o not is'la& t#e sa$e c#aracteristics. )nce a !racture is initi- ate %& an oil-%ase !lui* t#e 'r essure necessar& to 'ro'a(ate t#e !racture is $uc# s$aller %& co$'arison. #is is co$'oune %& lac+ o! a si(ni!icant 'ressure ro' across t#e !ilter ca+e o! $ost oil-%ase !luis. #is allo"s c#an(es
in "ell%ore 'ressures to %e trans$itte to t#e !or$ation $ore reail& an !ur t#er 'ro'a(ate t#e !racture. 7tuies #ave s#o"n t#at t#e 'ressure reuire to re-o'en a !racture is also lo"er "#en usin( an oil-%ase !lui. A !urt#er co$ 'lication is introuce i! t#e lostcirculation $aterial %ein( use acts to 'ro' o'en t#e !ractur e. As $entione earlier* 'r o'er ties uniue to oil-%ase $us nee to %e consiere "#en 'reventin( lost cir culation. #e $aor 'ro'erties an t#eir e!!ects ar e: K lo" 'ro'ert& i!!erences cause %& te$'erature. A!ter a %it tri'* it $a& %e necessar& to o'erate at a reuce !lo" rate until a !ull #ole c&cle is co$'lete.
…these materials increase the e#uivalent cir culating y densit
#is allo"s t#e $u to #eat to nor $al circulatin( te$'erature an viscosit&* 'reventin( unnecessaril& #i(# euiva - lent circulatin( ensities. 6u$' 'r es- sure i!!erences in ecess o! 100 'si in #eavier !luis are not unco$$on as t#e !lui #eats u'. K Due to (reater !lui e'ansion in co$- 'arison to "ater-%ase !luis* t#e $ea- sure $u "ei(#t "ill o!ten incr ease as t#e !lui cools on sur!ace as urin( a tri'. A(ain* t#ese i!!erences ar e $a(ni!ie at #i(#er $u "ei(#ts. or t#is reason* t#e te$'erature at "#ic# $u is "ei(#e s#oul al"a&s %e recore. #e te$'tation to reuce t#e $u "ei(#t in t#e 'its urin( a tri' s#oul %e resiste unless t#e "ei(#ts "ere ta+en at t#e sa$e te$'eratur e.
?se / to l%/%%l o! -I- II an/or / to ; l%/%%l o! L)-A< 2calciu$ car %onate. 7$all concentrations o! !ine N? 6L?@ 21 to 10 l%/%%l $a& also %e use. )t#er lost-circulation $aterials ten to cause "ater-"ettin( an loss o! electrical sta%ilit&. I! cir cu$stances reuire t#e use o! t#ese ot#er $aterials* t#e s&ste$ s#oul %e $onitor e !or t#eir e!!ects an treate accor in(l&. 6retreatin( "it# a "ettin( a(ent 2E
I NC)R6)RAIN@ L)7-
DIA)AC<)?7-
CIRC?LAI)N A
1. #e c#art %elo" s#oul %e use !or $iin( a iato$aceous ear t# 2Diaseal slurr&. A!ter t#e slur r& is $ie* ; l%/%%l eac# o! !ine $ica* $eiu$ N? 6L?@* -I- an cal- ciu$ car%onate 2L)-A< s#oul %e ae. #ese concentrations $a& %e $oi!ie e'enin( on rillstrin( (eo$etr &. /. 7et t#e %it at t#e to' o!* or o''osite* t#e loss 5one. Dis'lace t#e slurr& to t#e en o! t#e rill 'i'e.
lar(e
concentrations o! lost-circulation $aterials into t#e "#ole s&ste$ is not r eco$$ene since t#ese $aterials increase t#e euivalent circulatin( ensit&. #is o!ten co$'ouns t#e lost-cir culation 'ro%le$ instea o! solvin( it. o"ever * t#ere are so$e cases in "#ic# see'a(e losses can %e te$'oraril& sto''e or $ini$i5e %& carr&in( s$all concentrations o! lost-circulation $aterials in t#e s&ste$. Reco$$ene $aterials an concentrations are as !ollo"s: Diaseal
7M?<<<
-I ,AR
Diesel )il
E
Densit& 2l%/(al
l%
sac+s
l%
sac+s
(al
%%l
(al
l%
8
44.0
0.880
0
0.0
38.9
0.9
0.140
1.00
9
41.
0.84
G3
0.G3
3G.;8
0.89;
0.10
1.;0
10
38.;
0.GG0
18
1.8
3.18
0.81
0.;0
1.G;
11
3;.G
0.G14
181
1.81
34.8;
0.89
0.;0
1.G;
1
3.9
0.;8
3G
.3G
33.43
0.G9
0.;0
1.G;
13
30.0
0.00
91
.91
3.0
0.G3
0.;0
1.G;
14
G.
0.;44
34
3.4
30.G
0.G30
0.;0
1.G;
1;
4.;
0.490
400
4.00
9.30
0.98
0.8;
.00
1
1.8
0.43
4;4
4.;4
G.93
0.;
0.8;
.00
1G
18.9
0.3G8
;09
;.09
.;;
0.3
0.3;G
.;0
18
1G.0
0.340
;3
;.3
;.13
0.;98
0.48
3.00
Formulations !or preparing one barrel o! &eighted ,iaseal % slurry in diesel oil.
3. Close t#e ra$s. @entl& suee5e 2;0 'si $ai$u$ $aterial into t#e loss 5one at a rate o! 1 %%l/$in. ol t#e suee5e 'ressure 4 to 8 #r or until it issi'ates. easure t#e suee5e 'ressure on t#e annulus usin( a 0- to 300-'si (au(e. o avoi !racturin( ot#er 5ones* sa!e suee5e 'ressures in ecess o! $u #&rostatic 'ressure s#oul %e use. or ea$'le: De't# 2!t
7uee5e 6ressure 2'si
0 - 1*000 1*000 - ;*000
;*000 an ee'er
0 - 00 100 - ;00 ;00
()T*% !urface pressure plus mudcolumn pressure should never e'ceed overburden pressure /; psi8ft2
CALCI?-CAR,)NA
%. Restrictions in t#e rillstrin(. #e si5e o! t#e %it no55les* inter nal restrictions !ro$ D* $otors an ot#er tools a! !ect 'er$issi%le lost-cir culation $aterial concentrations. c. Al"a&s c#ec+ i! t#e 'u$'s or 'u$'in( units are eui''e "it# suction screens. I! so* t#e scr eens $a& nee to %e re$ove 'rior to 'u$'in( t#e 'ill. /. 7et t#e %it at t#e to' o!* or o''osite* t#e loss 5one. Dis'lace t#e slurr& to t#e en o! t#e rill 'i'e. 3. Close t#e ra$s. @entl& suee5e 2;0 'si $ai$u$ $aterial into t#e loss 5one at a rate o! 1 %%l/$in. ol t#e suee5e 'ressure 4 to 8 #r or until it issi'ates. easure t#e suee5e 'ressure on t#e annulus usin( a 0- to 300-'si (au(e. o avoi !racturin( ot#er 5ones* sa!e suee5e 'ressures in ecess o! $u #&rostatic 'ressure s#oul %e use. or ea$'le: De't# 2!t 0 - 1*000 1*000 - ;*000
;*000 an ee'er
7uee5e 6ressure 2'si 0 - 00 100 - ;00 ;00
()T*% !urface pressure plus mudcolumn pressure should never e'ceed overburden pressure /; psi8ft2 1
@?N>
7M?<<< )R )IL ?D7
11. I! 'ossi%le* rill "it#out r eturns t#rou(# t#e entire lost-cir culation 5one. 1/. 6ull out o! t#e #ole. easure t#e static $u level as 'r eviousl& escri%e. 13. Locate t#e loss 5one* usin( an a''ro'riate tec#niue as 'reviousl& escri%e. 14. A!ter locatin( t#e loss inter val* set t#e %otto$ o! t#e $iin( su% ;0 !t a%ove it. 7et a $ai$u$ suee5e 'r essure. 1;. 6u$' in a 10-%%l cus#ion o! "ater . a#ea o! t#e slur r& 1 1. i B l%/%%l o! CD 'ol&$er an /;0 l%/%%l o! E@-9 in "ater to t#e esire volu$e o! slur r& . 1G. Dis'lace t#e slurr& o"n t#e rill 'i'e an !ollo" it "it# 10 %%l o! "ater . 18. 7tart 'u$'in( oil-%ase $u into t#e annulus "#en t#e 10-%%l cus# ion o! "ater reac#es t#e $iin( su%. Close t#e ra$s. Control t#e 'u$'in( rates so t#e ratio o! slur r& volu$e to t#e oil $u volu$e is /:1. 6u$' rates o! 4 %%l/$in o"n t#e rill 'i'e an / %%l/$in o"n t#e annulus "ill usuall& %e satis!actor& "it# 41 B -in. rill 'i'e in GG B 8in. an lar(er #oles. 19. Dis'lace one-#al! o! t#e slurr& into t#e !or$ation at t#is !ast 'u$'in( rate. #e rill 'i'e $a& occasionall& %e reci'rocate slo"l& to inicate "#et#er t#e slurr& $i(#t %e $ovin( u' t#e annulus. I! t#e "ei(#t inica - tor s#o"s an& increase ra(* %r ea+ t#e connections an raise t#e 'i'e until it is !ree. a+e connections an continue is'lace$ent. #ere is no nee !or concern over s#ort s#uto"n 'erios since t#e slurr& #as no 'u$'in( ti$e li$itation insie t#e 'i'e.
10. Dis'lace t#e net uarter o! volu$e o! slurr& an $u at one-#al! t#e rate use in 7te' 9. 11. Dis'lace t#e re$ainin( uarter volu$e o! slurr& at one-#al! o! t#e rates use in 7te' 10. I! t#e #ole !ills* as s#o"n %& 'ressure on t#e annulus* atte$'t 2%& a #esitation suee5e to o%tain a 'ressure %uilu' usin( rates o! 1 %%l/$in into rill 'i'e an 0.; %%l/$in into annulus. ()T*% )ne barrel of slurry should be left in the drill pipe at the completion of the s#ueeze 1o not attempt to reverse circulate because mud will contact the slurry and gel up inside the drill pipe 1/. In instances "#ere t#e #ole cannot %e !ille* a 'ac+er s#oul %e set in t#e %otto$ o! t#e casin(. )il-%ase $u an slurries s#oul %e is'lace o"n t#e rill 'i'e in alternate %atc#es o! /0 %%l o! slurr& to ; %%l o! oil %ase $u usin( a s'acer o! 1 or / %%l o! oil %et"een slur ries. 13. A!ter t#e suee5e o%* 'ull out o! t#e #ole an "ait on t#e slurr& to set a $ini$u$ o! 8 #r %e!ore rillin( out. I! t#e !irst atte$'t is unsuc- cess!ul* re'eat t#e 'roceure a!ter "aitin( on t#e slurr& !or 8 #r .
6R
