mud loss course powerpoint-rjy-11 feb 2013

7/24/2019 Mud Loss Course Powerpoint-RJY-11 Feb 2013

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Ch-1:INTRODUCTION

TO

MUDLOSS

1


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What is Lost Circulation

Loss of drilling fluid to formation during drilling

Loss of cement slurry to formation during

cementing operations

Loss can be Gradual lowering of pits

Complete loss of returns

What is not Lost Circulation

Filtration loss

Filling of new hole by mud drilled at faster ROP

2


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Classification of Mud Loss

i!ided into three categories"

#eepage losses

Partial losses

#e!ere or total losses

$


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Seepage Losses

Rate of mud loss" %p to 1& barrels' hour for oil base mud

%p to 2( barrels 'hr for water base mud

#ometimes it may be ignored if mud loss also

ta)ing place with dumped cuttings from sha)ers

#tarts at !ery slow rate similar to filtration loss in

highly permeable formations

*


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+o find out whether mud loss is from surfacee,uipment or down hole #top drilling and pull the bit off-bottom.

#top all mi/ing 0 non-essential solid remo!al

,uipment Obser!e well for seepage losses with and without

circulation

Seepage Losses (Contd!

(


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D"illing too fast

When high drilling rates are attained e!en in hole

sies as small as 3.(45 suspected seepage loss canactually be attributed to other factors.

One such factor is normal displacement of drilled

solids with fluids. For e/ample5 while drilling (& feet per hour in

3.(4 hole5 $.( bbls 67&.8& cu m9 of drilling fluid per hour

will be re,uired to fill the new hole drilled.

:n 12-1'*4 hole5 ;.$ bbls 67 1.2& cu m9 of drilling fluid per

hour will be re,uired to fill the new hole drilled.

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D"illing too fast


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ecision to be made whether to drill ahead or

cure this first

:f formation damage and stuc) pipe primary

concern5 then cure this loss first.

:n e/ploratory area5 loss to be controlled beforedrilling ahead

#eepage loss in deeper pay one formations

also to be controlled =ay become partial' total loss if ignored for too

long

Seepage Losses (Contd!

3


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#a"tial Losses

Rate of mud loss" 1& to $& barrels' hour for oil base mud

2(-1&& bbls' hr for water base mud

:t may force to stop drilling ahead and tac)lethis mud loss problem first

:f drilling fluid can be made a!ailable and well

pr are within operating limits5 may drill ahead

with these losses.

>


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Se$e"e o" Total Losses

Rate of mud loss ? 1&& barrels' hour

Regaining full circulation is main priority

Reducing mud weight may be one of the

options for loss control but well has to be

monitored all the times for any influ/ in the wellbore

:f drilling fluid can be made a!ailable and well pr

are within operating limits5 may drill ahead withthese losses.

1%


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M&C'NISMS)

CUS&S

ND

#ROS#&CTI*&MUD

LOSS+ON&S

11


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Mud Loss Mechanis,s

+here are two mud loss mechanisms"

@atural losses

:nduced losses

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Natu"al Losses

+a)e place in %nconsolidated formations in top hole

Aighly permeable shallow sands

@aturally fractured formations Ca!ernous or !ugular limestones

1$

U lid t d ti


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Unconsolidated o",ations

Generally at shallow depths

in surface hole

@ormally consist of sand or

loose gra!els

Pores usually too large for

formation of a competent filterca)e.

Bery high permeability of 1&

-1&& m arcies in coarseunconsolidated formations.

nough for whole mud to be

lost 1*


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Unconsolidated o",ations (Contd!

Lost circulation may start while drilling5 tripping or

circulating mud prior to running casing. Loss usually starts with a gradual reduction in pit

le!el

Later on5 rate of loss may become more than ma/mud pumps discharge capacity if no remedial

action ta)en.

Loss can range from seepage to se!ere losses

and may sometimes lead to stuc) pipe.

1(


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Unconsolidated o",ations (Contd!

:mportant to pre!ent shallow losses as washingout of unconsolidated formations may form a

large ca!ity around the rig

+his is less stable and could ca!e-in from the

o!erburden.

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'ighl. #e",ea/le o",ations

=ainly depleted reser!oirs

Can occur at any depth. epletion due to producing

oil from formations in the

same field or nearby fields. Aigh permeability allows

entry of whole drilling fluid

into roc)s.

1;


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'ighl. #e",ea/le o",ations(contd!

Loss can be from seepage to se!ere depending

on porosity and permeability of formations

Can often lead to differential stic)ing pipe.

=ay cause formation damage

13


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Natu"al "actu"es

Loss occurs mainly in formations with natural

fractures or fissures.

Only thing re,uired by fractures is mud

hydrostatic pr to e/ceed the pore pr in the roc).

Can happen at o!erbalances as low as (& psi. :nitial loss can be seepage but li)ely to become

se!ere with passage of time if drilling continues.

+his type of loss difficult to cure as it may not belocalied but may be in large geological area.

1>


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Natu"al "actu"es

2&

"actu"es in co"e


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Fracture Porosity

01

N t l t (C td !


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Natu"al "actu"es (Contd!

Older5 harder and consolidated formations li)ely

locations for natural fractures. Created by geological mo!ements underground

Aigher fre,uency of occurrence near faults and

areas that ha!e been subected to tectonic forces . +his type of loss can cause some of the most

troublesome lost-circulation incidents.

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Ca$e"nous O" *ugula" o",ations

%sually in low pr carbonate 6limestone and

dolomite9 or coral reefs. :n limestone5 !ugs created by continuous flow of

water for !ery long time dissol!ing part of theroc) matri/ 6leaching9

+hus created !oid spaces often later filled withfluid.

When these formations are drilled5 drill string

may freely fall thru !oid ones accompanied withsudden loss of returns

2$


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2*

*ugs in co"e


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Vugular Porosity

0


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Ca$e"nous O" *ugula" o",ations (Contd!

Loss rate often e/ceeds ma/ mud pumpdischarge capacities.

Ca!erns can be localied or part of a more

e/tensi!e system Boids may range in sie from pinholes to tunnels.

Ca!erns are most difficult lost-circulation ones to

re-establish returns

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Ca$e"nous O" *ugula" o",ations (Contd!

:n many cases the well must be drilled Dblind45 i.e.5with no returns.

:f ca!erns are close to surface5 location collapse is

possible. Bolume of mud loss will depend on degree to

which !ugs are interconnected.

:n areas with a drilling history5 these losses areusually predictable.

2;

NATURALLY OCCURING LOSS ZONES


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NATURALLY OCCURING LOSS ZONES

I d d L


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Induced Losses

:nduced losses can happen in allformations.

+hese fractures occur when sum of

all e/erted pr on roc)s e/ceeds

fracture gradient of roc)5 causingformation to brea) down.

Once a fracture created or opened

by an imposed pressure5 difficult toheal and formation may ne!er

regain original strength.2>


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Induced Losses (contd!

Fracture propagation pr is always less than

fracture initiating pr. :t has been obser!ed that induced losses

account for maority of all the recorded lost-circulation incidents.


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Induced Losses:

Ci"culation Rate 2 &CD

Flow properties and circulation rate used should

de!elop minimum pr losses consistent with efficient

cuttings remo!al to a!oid pipe stic)ing and annulus

loading. /cessi!e circulation rate 0 fluid rheological

properties may e/pose formation to high pr 0

,ui!alent Circulating ensity 6C9.

$1

Induced Losses:


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Induced Losses:

Ci"culation Rate 2 &CD (contd!

:nsufficient circulation rate results in drilledsolids being loaded in mud causing high C.

+his increase in C may be sufficient to

induce losses.

$2

Induced Losses: &CD


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Induced Losses: &CD

C calculated by following e,uation"

C 6ppg9 HI 6ppg9J K HPa 6psi9' 6o.&(2+B 6ft99JM

Where

I =ud weight in lb'galPa pressure loss in annulus in psi

/ample"

:f I 1& ppg5 Pa (& psi5 +B 1&5&&&N

+hen C H1&J K H(&' 6&.&(21&&&&9JM

1& K &.1 1&.1 ppg$$

Induced Losses: 'igh #u,p #"


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g p

:f circulation after round trip started at normal

#P= may cause induced losses due tode!elopment of !ery high circulating pr

Pump pr surging also caused by increasingpump #P= too rapidly after pipe connections

+his condition occurs when drilling at deeperdepths.

Eecomes critical when present mud gradient isapproaching fracture gradient.

$*

Induced Losses : 'igh #u,p #"essu"e


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Induced Losses : 'igh #u,p #"essu"e

6Contd.9

/perienced in some wells in =umbai Aigh Pump pr. shoots to 12( )g'cm2e!en at 1&-1( #P=

when circulation resumed after round trip.

#lowly pr comes down and #P= can be increased

thereafter to normal #P=. +a)es time before we see returns due to less #P=

Aighly gelled mud on sha)ers at bottoms up.

$(


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Induced Losses: Su"ge #"essu"e

Lowering string too fast on connections cande!elop high surge pr

+ripping in string too fast can also de!elop

high surge pr. Running in casing creates piston effect and a

surge pressure.

+his can cause induced fractures

$8

Induced Losses: Su"ge #"essu"e


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(Contd!

+his problem made worse by Erea) circulation not carried out at regular inter!als

during R:A drill string in deeper holes with long

open hole sections

Pac)ed-hole assemblies

When drilling fluid has high gel strengths.

$;


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Induced Losses: Su"ge #" (Contd!

Erea)ing circulation5 rapid lowering of drillstring or casing can cause high pr pea) thatcan brea) down formation.

+hen induced fracture propagates rapidly atfracture propagation pr causing losses.

Fracture propagation pr is significantly lowerthan formation brea)down pr.

$3


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Induced Losses: &3cessi$e RO#

=ay result in huge amount of cuttingaccumulation in annulus when drilling in softformation in larger sie holes as mud may notbe able to lift drilled cuttings entirely.

Results in high C When formation with a low-fracture gradient

e/posed in OA section5 may lead to mud loss.

$>

Induced Losses:


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Sloughing o" Ca$ing Shales

:ncrease drilled solids in annulus5 causing !ery highC.

=ay also result in hole pac) off.

When annulus is restricted5 pump pr starts rising.

:f #P= not reduced5 high circulating pr whentransmitted to formation may cause fractures.

!en temporary pac) off can cause high pr

*&

I d d L 4 h t


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Induced Losses: 4ashouts

Aole washout leads to drop in mud !elocity inwashed out well bore section.

#o cuttings accumulate in washed hole section.

Cuttings also accumulate in larger sie rat hole

caused by casing short landing.

*1

I d d L 4 h t ( td !


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Induced Losses: 4ashouts (contd!


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Induced Losses: Mud 4eight

=inimum safe mud weight re,uired to "

Aold bac) formation pr


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Induced Losses: Mud 4eight (contd!

While drilling5 transition from an abnormallypressured one to a normal or sub-pressured

one may be encountered. /ample"

Ro)hia-1

Aigher mud weight will cause induced loss in

lower depleted or sub-normal ones

**

Induced Losses: Mud 4eight (contd !


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Induced Losses: Mud 4eight (contd!

+hese induced losses occur by hydraulically

fracturing of formations. Pr may be sufficient to cause whole mud loss

into permeable sandstone.

:f hydraulically fracturing of formationsuspected5 most probable point of loss is ust

below casing shoe.

*(

Induced Losses: 4ell Cont"ol


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uring well control situations5 loss can occur when

the well is shut-in. #hut-in pr transmitted down the well bore may

brea) the formation at its wea)est point.

:f well remains closed on gas )ic) withoutcirculating it out5 !ery high pr will be e/erted on well

bore.

+his not only results in lost circulation5 but losing

control of well.

*8



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*;

Induced Losses: 4ell Cont"ol (contd!


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( !

:f influ/ !olume is more5 shut-in pressures morewill be more

#o surface pressure e/erted on well bore will bemore.

:f proper procedures are not followed5 an

underground blowout can occur.

*3

Induced Losses:


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Inefficient 'ole Cleaning

Cuttings affects lost circ in se!eral ways. When hole cleaning inade,uate5 cuttings

accumulate in annulus5 loading up drilling fluid until

losses are induced.

:n de!iated wells5 cutting beds are not properly

eroded.

*>

Induced Losses:


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Conse5uences of Mud Loss du"ing


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D"illing IMM&DIT& CONS&6U&NC&S:

Aole instability

Lost time

Loss of mud

LON7 T&RM CONS&6U&NC&S: Reduced safety

Well )ic)s

%nable to reach +

#tuc) pipe

Poor cement ob(2



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D"illing +he loss of hydrostatic head that may result in a well-

control situation. +he reduction in the pr gradient may lead to wellbore

instability5 which could result in hole collapse and'or

stuc) pipe.

#ide trac)s or complete loss of the well.

Failure to achie!e ade,uate annular cement

co!erage.

Good ,uality formation e!aluation may not bepossible.

($



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#"i,a". Ce,enting

Reduced safety

Gas migration

Reduced annular co!erage

Poor one isolation


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Mu,/ai 'igh


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Locating the loss one position is paramount

to rectifying lost-circulation problems. Correct

identification of the position of the theft one

allows for proper placement of the lost-circulation

material.

+he theft one can be located from pre!iousdrilling records5 drilling rates5 drilling brea)s5

formation changes and from !arious logging

techni,ues.

(8

#OSITION O LOSS +ON&

:f th l i d hil d illi l


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:f the losses are e/perienced while drilling5 loss

one li)ely is on-bottom and caused by natural

fractures5 ca!erns or highly permeableformations.

:f losses are e/perienced while tripping or while

increasing mud weight5 the loss one probablyis not on-bottom and is a result of induced

fractures.

Recogniing a loss while tripping bac) into the

hole re,uires attention to the !olume of fluid

being displaced by the pipe.(;


+hi l b d t i d b ith i l


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+his !olume can be determined by either !isual

obser!ation or from regular e/amination of pit le!e

record. rilling into a sub-normally pressured5 naturally

fractured formation usually is indicated by a

sudden high loss of returns accompanied by anincrease in rotary tor,ue. +his is a reliable

indication that the lost circulation one is at bit

depth when no pre!ious problems ha!e been

encountered.

(3


L ll D / tt 8 if


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Losses are normally Don-/otto,8 if: +hey first occur while drilling ahead.

+he loss is accompanied by a notable change in ROP5tor,ue5 or drilling roughness.

Q :nduced fractures on-bottom can be caused by a

balled-up EA< or bit restricting the annulus. Q +he loss is due ob!iously to natural fractures5

faults5 ca!erns5 !ugs or high-permeability sands

and gra!els

(>


Losses are normally Doff /otto,8 if:


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Q Losses are normally Doff-/otto,8 if: +hey first occur while tripping5 drilling fast or increasing

drilling fluid weight. +hey are ob!iously the result of an induced fracture.

+hey are result of shutting the well in and )illing well.


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Ch-0:DRILLIN7 #RCTIC&S

TO

#R&*&NT

LOST CIRCULTION

81

Ma9o" Issues


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Proper setting depth of intermediate casing

/cessi!e bottom hole' down hole pressures

created during operations.

Correct drilling practices and their

implementation to reduce se!erity 0

conse,uences of loss circulation .

82

Setting Depth of Inte",ediate Casing


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g p g

#etting of intermediate casing abo!e transitionone to be a!oided to pre!ent penetration of

wea) formations with higher mud weight.

+he intermediate casing to be landed after

confirming passage into transition one.

8$

&3cessi$e '# (otto, 'ole #"essu"e!;

D'# (Do


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D'# (Do


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+hic) mud ca)e.

/cessi!e annulus loading. rilling too fast.

Ealled up EA< 6bottom hole assembly9' down

hole drilling tools. =obile formations

%nder gauged hole

88

'igh Mud 4eight


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ach formation has a certain fracture strength. :f hydro static head due to mud column

e/ceeds this strength5 formation may get

fractured.

8;

Cont"ol Measu"es


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eep mud weight in the median range betweenpore pressure and fracture pressure.

Run solid control e,uipments regularly to )eep

LG# 6low gra!ity solids9 to minimum le!el.

=onitor mud weight !ery closely.

83

'igh &CD


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D ,ui!alent circulating density 6C9 isalways higher than running mud weight due to

resistance to flow of mud across well bore wall

and presence of cuttings in the annulus.4

8>

Cont"ol Measu"es


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/cessi!e !iscosity and gel strength to be

a!oided. Formation cutting loading in well annulus to be

restricted.

+hic)ness of filter ca)e to be limited to a!oidreduction of annular clearance.

=ud weight to be optimum and any increase of

=W to be slow 0 gradual.

;&

Cont"ol Measu"es (contd!


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Fluid columns in the well bore ' annulus to bebalanced.

Earites sag to be a!oided by controlling mud

rheology .

LG# 6low gra!ity solids9 0 =E+ 6methyl blue

test 9 !alues to be )ept at minimum possible

le!el.

;1

'igh Mud Ci"culating Rate


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:t causes increase in C.

Aigh rate of flow across wea) formation

causing hole erosion and mud loss.

;2

Cont"ol Measu"es


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%se optimum flow rate for efficient holecleaning.

Birtual hydraulics may be used for this.

;$

Mud #u,p #"essu"e Su"ges


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=ud circulation after running in to bottom tobe started at slow circulation rate of mudpump.


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;(

or stopped suddenly. This is increased by high gel structureof the stationary drilling fluid, which needs to be broken

before it starts to flow. Rotation of the pipe, prior to kicking-in the pumps, can reduce the surge pressure as can areduction of the gel strength of the mud prior to any trips.

S


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. p4500

4000

3500

3000

2500

PSI

STATICPOOH-STEADY

SPEED

STATIC

STATIC

RIH-STEADY

SPEEDSTEADY CIRCULATION

SWAB

SURGE

TRIP MARGIN

SHP =3200 psi

ACCELERATE

ACCELERATE

D

ECELERAT

E

DECELERAT

E START

PUMPS

FRACTURE PRESSURE = 5500

pi

FORMATION PRESSURE = 2!00 pi

ANNULUS FRICTION

PRESSURE

=>

Q Pressure Surges when tripping. Run drill pipe and casingbelow critical speeds for running pipe and casing and these


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;;

below critical speeds for running pipe and casing and theseshould be used to avoid losses.

Q Rapid pipe movement while circulating or reaming can alsocause surges that can result in losses.

#"actices to $oid #"essu"e Su"ge


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+a)e *(-8& seconds to run in and pull out onestand of drill pipe 6!ertical well9.

+his will help to a!oid pressure surges andswabs and pre!ent fatigue failure or sudden

fracture of !ulnerable formations.

;3

Dispe"si/le Mud ; o",ation


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ispersible mud ' formation also causes

increase in !iscosity ' mud weight .

+his effecti!ely increases mud wt. ' annular

friction losses.

;>

Cont"ol Measu"es


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:ntermediate mud circulation for gel brea)ing.

Periodicity5 duration and depths for circulation

to be decided by drilling crew in consultationwith the mud engineer on case basis.

3&

Contd


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Preferably circulate ust before and afterdrilling of dispersible formation.

#uitable non-dispersible mud system may be

used.

31

Thic? Mud Ca?e


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+hic) mud ca)e can also cause mud loss asclearance between drill string and well bore walldecreases depending upon thic)ness of theca)e.

Fre,uent wiper trips5 preferably once in 2* hrsof continuous drilling to be done in general.

Water loss of drilling fluid should be )ept to aminimum.

32

&3cessi$e nnulus Loading


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+his can happen due to insufficient discharge

and improper hole cleaning.

rilling at a !ery fast rate-it is not feasible to

clean the hole with recommended pump ratein general.

+hic) cutting beds Causing Aole pac)-off.

3$

'ole Cleaning Difficult. *s 'ole ngle

4IT' T'& SM& DISC'R7&'OL& CL&NIN7 DIICULT@ T


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*RIOUS 'OL& N7L&S

1% A% >%'OL& N7L&

B

'OL&

CL&(NIN7

=%

3*

'ole Cleaning #"o/le,s


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o.cott Settling Regions Of Inclination

alled-up '; D"illing Tools

+hi bbi hil POOA 6 lli


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+his may cause swabbing while POOA 6pulling

out of hole9 and surges while R:A 6running inhole9.

#wab may cause destabiliation of well bore 0e/posure of wea) formation.

#urge may increase EAP'AP 5 causing

fracture ' loss circulation.

38

Cont"ol Measu"es

%se of proper mud systems to pre!ent


87/372

p p y p

dispersion of gumbo li)e clay in the mud.

%se proper discharge to pre!ent re-grinding and

floating of cuttings in the annulus.

%se chemical sweeps to clear ball up from the

EA


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=obile formations li)e salt 5 plastic shale andsome coals ha!e a tendency to flow inside the

well bore under o!erburden pressure.

+his results in tight and under gauged hole.

33

Mo/ile o",ations


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Cont"ol Measu"es


90/372

=a/imum allowable mud weight may help.

Fre,uent wiper trips may help.

%se of suitable mud system may also help.

>&

Unde"-gauged 'ole


91/372

Can be caused by undergauged drill bit.

+CR bit run after PC bit run.

=obile formations.

>1

Unde"-gauged 'ole


92/372

0

Cont"ol Measu"es


93/372

DOn each run a pulled out bit should be gauged

and while lowering new bit reaming should be

done !ery slowly to a!oid hole pac)-off and

mud loss in wea) formations.4

>$

Clea"ing 'ole #ac?-off; "idge


94/372

%sing high pump rate to clear bridge' pac) off

not only aggra!ates bridge further 5 it may

also cause formation fracture and mud loss.

+or,ue and slac) drill string with only $&&-(&&

psi pump pressure to regain circulation andincrease pump rate slowly till bridging is

cleared completely.

>*

#u,p Rea,ing Rate


95/372

Ream slowly to a!oid pac)-off.

>(

Causes of &3cessi$e '# ; D'#

4hile Casing Lo


96/372

g g

Lowering casing too fast.

Bery little clearance between casing and well

bore wall.

Aighly !iscous mud.

:mproper hole cleaning before casing lowering

>8

Cont"ol Measu"es

Birtual hydraulics can be used to simulate


97/372

y

surface pressures 0 C while circulatingmud based on annular clearances.

@ecessary adustments to be made to pro!ide

sufficient annular clearances to a!oid high

pressures during mud circulation.

>;

Contd


98/372

=ud parameters to be optimied to a!oid

gellation of mud during casing lowering.

:ntermediate circulation as decided between

:C 0 mud chemist may be gi!en.

Aole to be thoroughly cleaned to remo!e

cuttings from the well bore.

>3

Cont"olled D"illing


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D:n )nown wea) areas it is a good practice todrill slowly and allow healing time for formation

of protecti!e layer of mud ca)e on the well bore

wall.4

>>


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ST DRILLIN7

CONTROLL&D DRILLIN7

DRILLIN7 TIM&

4&LL

DT'

1%%

RO#igh R!P can cause annulus loading by the cuttings, which willincrease the "quivalent #irculating $ensity %"#$& and can


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1&1

increase the "quivalent #irculating $ensity %"#$& and can

cause losses. Software can be used to monitor the situation andmaintain annular pressures within the required parameters forloss free drilling. Parameters which may be needed toaccompany high R!P are mainly hole cleaning issues but can

also be rheological %increase in viscosity to carry the cuttings ora decrease to increase turbulence&, hydraulic %increase in pumprate& or a combination. Resultant changes to increase R!P canhowever cause losses.

Cont"olled D"illing Techni5ue

rill !ery slowly in the suspected thief one


102/372

rill !ery slowly in the suspected thief one.

Obser!e well beha!ior after e!ery S - 1 m of

drilling.

#top and ta)e remedial measure if loss is

encountered.

1&2

Cont"olled D"illing Techni5ue (contd!


103/372

+his will allow for time to heal the suspected

formation.

:t will also pre!ent instant cutting loading in the

well annulus.

1&$


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4&LL #LNNIN7TO

*OID MUD LOSS

1&*

#lanning spects

Proper casing setting depths.


105/372

Proper casing and hole sie combination

Pre-drilling meetings'spud meetings

#ounding ' alerting all concerned

1&(

Contd

# ffi i t l i l ti t l t i l


106/372

#ufficient loss circulation control material.

rilling of pilot hole.

Chec) list

1&8

#"ope" Casing Setting Depths

Casing setting depths to be carefully selected


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Casing setting depths to be carefully selected

based on a!ailable prognostic data. Fracture prone formations ' ones to be

isolated with casing before opening a higherpressure regime formation.

Proper care should be ta)en to ma)enecessary corrections in geological prognosis5if any5 duringthe course of drilling

1&;

#"ope" Casing SiEe and 'ole SiEeCo,/ination


108/372

Eased on pore pressure and fracture gradients5proper combination of casing 0 hole sie to be

selected to limit C effects.

Birtual hydraulic programmes to be utilied to

simulate the situation based on casing O5

hole sie and planned mud system.

1&3

#"e-d"illing Meetings; Spud Meetings

Offset well data should be studied carefully and


109/372

necessary recommendations should beincorporated in spud meeting minutes.

uring the course of drilling5 regular safety

meeting may be held to )eep contingency plan in

place.

+his will also wor) as a reminder to all concerned

about best drilling practices while drilling through

a loss prone formation.

1&>

Sounding ; le"ting ll Conce"ned


110/372

FEefore opening loss prone formation 5 all

concerned should be informed ' alerted about the

haards in!ol!ed and le!el of preparedness

re,uired .4

11&

Sufficient Loss Ci"culation Cont"olMate"ial


111/372

DEased on off-set well data 5 before drilling into

loss prone one5 sufficient ,uantity of suitable

loss control material to be )ept at drill

site'accessible location.4

111

D"illing of #ilot 'oles

One or more smaller pilot holes may be drilled

before enlarging it to the re,uired sie


112/372

before enlarging it to the re,uired sie.

+his will reduce e/posed surface area of well bore5

reduce annulus loading with formation cuttings and

allow for healing of formation with time.

+his is especially helpful in the top section of the

well.

112

Chec? List

Offset well data'reports a!ailable and studied.

Procedure for necessary action in case of lost


113/372

Procedure for necessary action in case of lost

circulation is a!ailable.

+ype and amount of LC= material that may be

re,uired based on offset data is a!ailable.

:dentify and maintain sufficient stoc)s of LC=material at site.

Communication networ) amongst all concerned

to meet e!entualities.

11$

Contd

Roles and responsibilities of each of the


114/372

Roles and responsibilities of each of the

drilling crew members be defined to tac)le a

mud loss situation.

:n case of e/pected surface seepage5 all li)elyspots identified and monitored.

11*


115/372

CS&

STUDI&S

11(

FCase Stud.-18-('3 D casing was lowered with shoe at 1(8&


116/372

m.+ransition one was at 1>$( m. #imultaneous loss-acti!ity situation was

encountered causing considerable loss of rig

time.

:n Langnese -( 5 >-('34 casing was planned 0

set ust abo!e high pressure one6 into the

transition one9.

+he well was successfully completed withoutany complication.

118

I,p"ope" Inte",ediate Casing SettingDepth


117/372

T"ansition Eone at 1A ,

-;8 casing shoe-1>% ,

4ea? fo",ation H,ud loss

'igh p"essu"e Eone-


118/372

d"illing data:

:t was planned to lower intermediate >-('34

casing at $(3& m as per G+O.

:n the final section mud weight re,uirement as

per G+O was 2.1( sp.gr.

uring course of drilling well acti!ity was

encountered at around $$2$ m. =ud wt.

gradually increased to 1.82 sp.gr. LO+ !alue for 12-1'*4 phase was - 1.(2 sp.gr. 113

Contd

G+O was re!iewed based on actual data and


119/372

casing was lowered with casing shoe at $$;3m against a plan of $(3&m.

+his sa!ed wea)er section in 12-1'*4 phasefrom getting fractured by hea!ier mud

re,uirement to drill further.

11>


120/372

Ch-A:C&M&NT S LCM 4'IL&

DRILLIN7

10%

C&M&NT TR&TM&NT S LCM%sing cement systems can lead to good results5

but the disad!antage is time consuming

process. :t can then damage the permeability or


121/372

be lost entirely to the formation

Cement is not acid soluble and can not be

remo!ed once in place.

amage to the formation is permanent

Cement set-time can not be controlled

accurately

Cement drilling damage the drilling fluid

101

LOSS CIRCULTION 4'IL& DRILLIN7

=ost of the LC=


122/372

treatments are oftemporary in nature and

should create a barrier to

withstand the effects of

drilling such as surgeand swab pressures5 and

remo!able by etting '

washing.

100

"idging agents effecti$e upto J inch


123/372

Ce,ent slu""ies can seal J inch to 1 ft


124/372

setting p"ope"tiesCe,ent s.ste,s that gel up

Thi3ot"opic s.ste,s

7el o" set up instantaneousl. due to

che,ical "eactions

o",ation of filte" ca?e assisted /. lost

ci"culation p"e$ention additi$es

10B

Thi3ot"opic s.ste,

C=@+:@G #T#+=#


125/372

Sodiu, silicate and ce,ent

#o"tland ce,ent


126/372

st"uctu"e

SODIUM SILICT& ND C&M&NT

#o"tland ce,ent


127/372

5 .

Space" fluid "e5ui"ed to p"e$ent ha"dening

in the pipe

S,all space" fluid $olu,e) co,ponents,a. "eact in the pipe

La"ge space" fluid $olu,e) co,ponents

sepa"ated and p"e$ent the "apid setup10=

POR+L


128/372

sulfate can seal off lost ci"culation Eones

Set ti,es can /e cont"olled /.

pe"centage of calciu, sulfate p"esent

to so,e e3tent /. ce,ent "eta"de"s

Re5ui"es ca"eful d". /lending

10


129/372

oth of these ,ethods a"e 5uite "is?.)and e3t"e,e ca"e ,ust /e used to

ensu"e that the ce,ent sets in the lost

Eone) not in the d"ill pipe

10

Massi$e Losses in Ca"/onate o",ations

Carbonate formations li)e limestone and dolomite fre,uently ha!e!ugs5 fractures5 or open channels filled with normally pressuredfluids.


130/372

+his type of ultra high permeability lost circulation is difficult tocure with con!entional LC= bridging agents.


131/372

de!elopment. =agnesium base and thi/otropic cement are more effecti!e and

forms rapid gels to resist being wash out. #odium silicate with cement also pro!ides effecti!e results Cement slurry with synthetic fibers and bridging material pro!ides

effecti!e filter ca)e deposition. :f the pill failed to follow the losses path at least some minimumdistance from wellbore5 losses can return.

Losses can also occur if bit side trac)s or penetrates the new path.

Loss one is not always at bit5

1A1

F:ER C=@+

Ine"t


132/372

solids f"o, slu"". p"e$enting fu"the" loss

i/e"s in con9unction


133/372

1$$

Fiber based LC=

=icronied synthetic fibers


134/372

#ie" 12mm5 8mm and

*mm

=i/ing" prior to pumping

Good fluidity @o pumping problem

Cross-netting

1AB

#OLB# #BR LO## C:RC%L


135/372

can be designed for +otalloss circulation while drilling

1A

ER:G


136/372

1A>


137/372

< slurry of rapid settingmaterial 5 acti!ated withtemperature5 sets at rightangle5 e/hibits similarcharacteristics asportland cement but?>& acid soluble. :t canbe pumped through theEA< to combat all static

or dynamic losses.1A=

Magnesiu, ase Ce,ent

+he magnesium based pills are downhole acti!ated blends ofinorganic5 al)aline earth compounds

d$antages :

t i i l i i h dli i t C l t


138/372

oes not re,uire special mi/ing or handling e,uipment. Completeacid solubility5 but reaction is se!erely limited. Aigh compressi!estrength and low shrin)age. #ets and gains full strength rapidly5 thusminimiing lost rig time

#"epa"ation and #lace,ent:

Reta"de" 2 $iscosifie" is added into a mi/ing tan) containing freshwater or brine followed by the re,uired amount of magnesium andallowed to stir until well blended. ead burned magnesite is addedand the slurry is displaced downhole. Pull the pipe to a safe pointabo!e the pill and wait the recommended time prior to circulating or

drilling.

1A


139/372

1A

LIMITTION O C&M&NTIN7 SOLUTIONS

Cement slurries not effecti!e against induced !ertical

fractures.


140/372

:f fluids flowing within the fracture or from an upper

one into the fracture 6cross flow95 the cement slurry

wash away and no seal obtain.

:n case of flowing within the fracture circulation

restored but loss reoccurs when plug drilled out

:n case of cross flow5 no cement slurry found at all

1B%

+o be effecti!e5 the loss control techni,ue and materialsmust be functionally related.

F il d t t bli h l


141/372

Failed to establish loss-one. Lost circulation materials are not matches to the typeand se!erity of loss-one

Reluctant to apply proper techni,ue to match these!erity.


142/372

LOST CIRCULTION #R&*&NTION

DURIN7 #RIMR@ C&M&NTIN7

1B0

Loss 4hile Ce,enting Lost circulation problems while cementing may re,uire Dfoam

cement45 lightweight slurries5 or stage cementing to limit C andfinal hydrostatic pressure.

Cement plugs used to seal a loss one often fail as a result of their


143/372

Cement plugs used to seal a loss one often fail as a result of theirdensity. Reducing cement density also reduces compressi!e strengthand bond strength. Lower density slurries can also reduce muddisplacement efficiency.

Ceramic microspheres can reduce the density as low as >.& lbs'gal. Foam cements ha!e also been used for reducing the cement

slurry density below 1& lbs'gal. +ypical densities ha!e ranged from 3.& to >.& lbs'gal.

Often5 losses are such that drilling blind 6with no returns9 is used to

drill through the loss one and into a competent formation prior torunning casing.

1BA


144/372

Lost circulation during primary cementing operations

re,uires e/pensi!e remedial wor) and some of the

damages are permanent.

PRB@+:O@


145/372

:nade,uate fill-up across potentially corrosi!e water

ones

Lea)ing gas ones behind the casing

:nade,uate casing support to sustain stress offurther operations

Casing not ade,uately supported to resist collapse

from flowing salt sections

@on fulfillment of regulatory re,uirement1B

FR F


146/372

Lost ci"culation often caused du"ing this

phase e$en

C


147/372

,a3i,u, "unning speeds fo" a gi$en set ofhole conditions

Conside"ation fo" d"illing fluids thi3ot"opic

/uildup due to little o" no ,o$e,ent Ci"culation should /e /"o?en at f"e5uent

inte"$als in cased and open hole section

1B=


148/372

PRB@+:O@ ET #:=%L


149/372

2&

&&

*&&&

Welle!iation

1.& 1.2 1.* 1.8 1.3 2.&

g

Formation Press.

Frac

Pore

&

2&&&

*&&&

m

'4#(S)*+

/4

#(S)*+

1*>

%#%


150/372

to type and se!erity of the loss one

:nade,uate records of the past e/perience

rilling mud brea)s through the cement plug before itsets

Lac) of sufficient information and wrong treatment

results repetiti!e failures and costs' time o!errun1%


151/372

ER:F OF LO## C:RC%L


152/372

10


153/372

one may be determined with the )nowledgea!ailable at the rig site asV formation and operation.:t is established that more than half of losses onesoccur ust below the pre!ious casing shoe.

etermine the se!erity of mud loss" etermine the

rate of loss and static mud column height. Calculate the pressure of loss-one Calculate the static mud weight which the one will

support.

1A


154/372

1B

=ethods of treatment #onventional 0ost #irculation 1aterials, fibers, flakes, and

granules

igh 2luid 0oss Squee3es, diatomaceous earth or clay blends

+unks, $!4 to $!45#


155/372

+unks, $!4 to $!45#

Precipitated #hemical Slurries, silicate and late6

Resin-#oated Sand

#rosslinked Polymer Slurries, PP(, guar, "#, etc.

#ements

4arite Plugs

$ilatant Slurries

1

Con!entional -LC= +he most successful use of con!entional LC= occurs with a mi/ture

of types and particle sies. :n some cases5 as much as ;& to 3&lbs'bbl of a mi/ture of LC= should be used as a pill. Generally5 aconcentration of *& lbs'bbl of a properly sied LC= will stop losses to

permeable or fracture ones. < combination of fiber5 fla)es5 andgranular material should be part of the same pill < typical mi/ture


156/372

p 5 5granular material should be part of the same pill. < typical mi/turewould be * parts granular5 2 parts fiber5 and 1 part fla)e.

+he con!entional pill should be as !iscous as possible for ease ofpumping and displacement. Bolumes of con!entional pills may !ary

from 2& to 1&& bbl5 depending upon hole sie and se!erity of loss.+he pill should be made with the fluid ma)e-up water for water baseapplications and with the oil or synthetic for non-water systems.

:f LC= materials of greater sie ieV more than 1'$ of nole dia.5 it is

recommended that they be pumped through open ended drill pipe.1>

Con!entional-LC=

+he )ey to sol!ing lost circulation using con!entional LC= isto ha!e sufficiently large particles to first bridge the largestopenings of the pores or in the fracture with rigid granular

LC= materials and second seal the bridged opening withdeformable fibrous and fla)ed LC= material used


157/372

g p gdeformable fibrous and fla)ed LC= material used.

Con!entional LC=s can be classified by the particle shapeinto 19 fibers5 29 fla)es5 and $9 granules.

=ost LC=s are waste by-products of other industries5particularly agricultural5 and their a!ailability may !arydepending on the location.

=ost con!entional LC=s are labels as being Dfine45 Dmedium45or Dcoarse45 there are no standards.

1=

LC= Plugging =echanism Eridging agents form a bridge of particles across the fracture or

collect in the interstices of a permeable one. For a bridge to form5

the bridging agent must contain particles that are no smaller than S

of the opening sie to be bridged. +his is true for either permeable or


158/372

p g g pfractured loss ones.

Eecause it is hard to )now the sie of a fracture or the sie of the

pores in a loss one5 lost circulation materials that use bridgingagents must contain a selection of !arious lost circulation materials. %

7un? Slu""ies Gun) slurries are downhole acti!ated plugs consist of a high

concentration of hydratable materials in diesel oil and are acti!atedwhen they become mi/ed with mud as they e/it the bit. +hey areespecially applicable to conditions with high static losses.


161/372

Gun)s ha!e a low !iscosity inside the drill pipe and can generally bepumped through the bit. When placing a gun) slurry5 the gun) isgenerally pumped with a cement unit down the drill Pipe.

:t is highly desirable to pump gun) slurries using two pump rates one ratio high enough to allow a less !iscous material to penetrate5followed by a lower ratio so that a more !iscous material is placed atthe end.

1>1

7un? Slu""ies +he most common are" iesel Oil K Eentonite 6OE9 iesel Oil K Eentonite K Cement 6OEC9

iesel Oil K Eentonite K 2 Cement 6OE2C9 iesel Oil K


162/372

p g y 6 9

#lurries without cement do not de!elop true compressi!e strengthand would not be long term solutions to situations where a highdifferential pressure is e/pected.

+he industry generally considers OE2C to be one of the best lostcirculation remedies a!ailable. OE2C has the main ad!antages ofgun) in being able to generate e/treme and immediate downhole!iscosity to slow and seal losses5 plus the ad!antages of cement to

withstand differential pressures.1>0


163/372

Diesel Oil;entonite;Ce,ent (DOC) DO0C! iesel Oil Eentonite Cement 6OEC9 is a hydration-type plug . +he cement

allows the pill to de!elop compressi!e strength o!er time.

+he ratio of bentonite and cement can be !aried to alter the final compressi!e

strength. +he final strength of OEC is determined by the pumping ratio of

OEC to fluid and the bentonite to cement ratio. +he starting ratio of the fluid toOEC is usually * to 1 and produces progressi!ely firmer plugs as the ratio of


164/372

OEC is usually * to 1 and produces progressi!ely firmer plugs as the ratio of

fluid to OEC decreases to 1"$.

OEC is intended for those difficult situations where con!entional lost circulation

materials and OE ha!e failed. Low to/icity oils5 such as mineral5 synthetic based5 or !egetable oils5 may be

suitable5 but should not be used before laboratory e!aluation for suitability.

+he synthetic based fluids are recommended when en!ironmental regulations

preclude the use of diesel or mineral oil.

1>B


165/372

Mi3ing Re5ui"e,ents +wo cement pumping units should be used for a OEC s,ueee. One pumping unit will

pump the OEC down the drillstring and the second unit will pump fluid down the annulus.

+he presence of water in the base oil causes acti!ation of the slurry to a degree relati!e tothe

contamination. +he result will be seen in higher !iscosity and lower slurry density due to the

water acti!ating the cement to set. #teps to dry the water from the oil prior to adding the

cement allows a higher concentration of cement to be added into the oil.

+he oil should be either )erosene5 diesel oil or other suitable oil.

+he moisture content of the bentonite will also affect the results.

1>

Contd. #"epa"ation Pilot test the OEC and a,ueous fluid mi/ ratios to !isually obser!e

the results.

etermine the !olume of OEC to be pumped. +ypically5 a *& barrel


166/372

batch is used5 but site specific conditions should be considered.

Flush all pumps5 mi/ers5 lines5 and tan)s that will be used to prepare

the OEC with diesel oil.

fluid or water in the suction lines and pumps. < low pressure gauge installed to monitor s,ueee pressure .

:nstall a bac) pressure !al!e in the drillstring.

1>>

Contd. #lace,ent Pump ( to 1& barrels of diesel oil spacer followed by the OEC pill and

another ( to 1& barrels of diesel oil spacer to isolate the OEC from the

fluid. Pump enough fluid to place the bottom of the pill at the bottom of the

pipe. Close the pre!enters and commence pumping down the drillstring at a


167/372

Close the pre!enters and commence pumping down the drillstring at a

ma/imum rate of * to 3 barrels per minute. =onitor annular pressure gauge

reading and control the pressure to a ma/imum e,ui!alent of 1.( ppg fluid

weight. =aintain pressure on the well for appro/imately $ hours. Circulate

and condition the fluid at the bottom of the casing for at least two annulafluid !olumes while carefully monitoring for fluid loss before tripping the

pipe.

Circulate and condition the fluid at the casing shoe before entering the open

hole. Wash and ream the open hole slowly to a!oid pushing the bit into the OEC and possibly pressuring up the hole.1>=

DO

O


168/372

11;.3 lbs of attapulgite

>8.* lbs of bentonite.

+he mi/ture yield is appro/imately 1 bbl and the slurry density is 1&.8 lbs'gal

62 diesel9.

Silicate 2 Late3 Slu""ies Eoth sodium silicate solutions and commercial late/ additi!es used for

cementing can be made to precipitate and plug loss ones when pumped in

combination with calcium chloride. +he general scheme is to pump a calcium

chloride pill followed by the silicate of late/ slurry. When these two slurriesmi/ in the open hole hopefully adacent to the loss one they form a !iscous


169/372

mi/ in the open hole hopefully adacent to the loss one5 they form a !iscous

plug which can slow and seal many loss ones.

While sodium silicate has been used for many years in combination with los

circulation while cementing5 late/ appears to ha!e the potential for beingsignificantly more effecti!e .

Late/ reacts faster5 forms a cohesi!e mass5 and is applicable in oil-base muds. Oil

base mud also acts as an acti!ator of late/ so that mud contamination would not

necessarily render the slurry ineffecti!e

1>

U-Lin) LC= For Reliable Circulation Control

Formulation remained li,uidand gelling started only afteraddition of the acti!ator

G l ti i d b


170/372

Gelation period can becontrolled as perre,uirement

Form Polymeric stiff rubberygel to create impermeablebarrier at the lost one

C"osslin?ed #ol.,e"s Guar gum has been used for many years to build lost circulation pills of a

!ery stiff5 plug-li)e consistency when an acti!ating chemical is added. PAP


177/372

1==

ER:G


178/372

1=

#:B 1"-(&&Xm

2"-2.&mm

$"-*.&mm#L:+ *"-$.&mm

ifferent sie of

Perforated plate"-


179/372

$ *

12

1=

Ch-*"

C


180/372

C:RC%L


181/372

WA@ LO#+ C:RC%L


182/372

p

Carbonate formation" swift loss

#hale formations" slower 0 progressi!e

:nformation pertained to operations

Change in mud weight

Rapid mo!ement of the drillstring

10

CORRC+:B =


183/372

and match the remedial material and techni,ue to it

in terms of both the sie of the material and itNs

return

1A

C


184/372

LC= s are not systematically matched.

Reluctant to proceed with re,uired techni,ue.


185/372

1


186/372

1>


187/372

1=


188/372

1

DIS#&RSIL& I&RS

=icronied synthetic fibers

#ie" 12mm5 8mm and *mm


189/372

5

=i/ing" prior to pumping

Good fluidity

@o pumping problem

Cross-netting

Disersi!le Fi!ers1

ER:G


190/372

1%

LC=" CRO##-L:@ GL

Cross-lin)ed polymer gel used as LC=

pro!ides circulation lost control

While drilling

Polymer based gel shrin) with time and

reopen the fractures


191/372

reopen the fractures.

#uch LC= may starts cross flow

Polymer gel may stic) to formation and

can damage the permeability

=ost of the gels are not biodegradable or

can not be remo!ed.

11


192/372

10

I&LD IM#L&M&NTTION O

C'&MICLL@ CTI*T&DCROSS-LIN&D #OL@M&R 7&L


193/372

S LOSS CONTROL #ILL

1A


194/372

Se5uence of Loss Cont"olOpe"ation du"ing d"illing

Loss-Eone at 0%M

#laced %B LCM #ills 0 '#L4 Ce,entslu"".61.(2-1.(&9


195/372

El drilling u.t. 231&.(=

@o ret. Cont. drilling-*m LC= Pills at 231*.(=

@o returned

1

Elind drilling upto 231>.(=

#tatic mud le!el at 1*&-1(&=

Placed 2 LC= pills K $ cement plugs


196/372

@o returned

#tatic =ud le!el at 11&-12&=

Placed Cross-lin)ed Polymeric Gel followed

cement plugs 6sp gr 1.8*9

1>


197/372

1=


198/372

1


199/372

CS& STUD@ O 4&LL

*S&G1>


200/372

0%%


201/372

0%1


202/372

0%0


203/372

0%A

esigned formulation acti!ated

abo!e *2-*(&C. Planed to use

accelerator for low temperature


204/372

accelerator for low temperature

$8&

C6Y*2&

C9.

0%B


205/372

0%

Made a""ange,ents fo" > tu/e


206/372

0%>

&ffo"ts to

o$e"co,eloss

Water based drilling

fluid" =W 1.&$-

1.&(5Bis. *&-*3 sec. uring loss control

=W" &.>(-&.3(

epth

m

Eentonite

in +ons

Chemicals in )g

*12 *.> PAP 1&.& #-2&bgs5 cement-1&bgs5 A#-2&&lt5

=anila rope-(bgs etc

*3& *.; =ica-8;5 carpet fib-*bgs5rope fib-;bgs5

Gunny bag fib-1&bags


207/372

Bis $3-*3 sec

----%sed surfactant to

reduced =W

y g g

*>3 2.& =ica-1(&)g5#-;bgs5 rope fib-(bgs

(&* 1.** =ica-(&5 rope fib-2bgs5 #-2bags

(18 &.8& =ica-1&&5rope fib-(bgs5#-2bgs

(22 1.33 =ica-2&&5rope fib-(bgs

0%=


208/372

2 Lead APLW slurry with&.2( fiber5 #p gr-1.*8

12.& 1$.&

$ +ail APLW slurry with outfiber5 #p gr-1.*8

12.& 1*.&

F:@:@G"- F%LL R+%R@5@O LO##0%

CONCLUSIONS

Plugging efficiency of cement slurries has impro!ed by

solids and fibers.

Fiber concentration of &.2(6EWOE9 for light weight

cement slurries 6sp gr 1.(& ' 1.2(9 is an ideal system.


209/372

cement slurries 6sp gr 1.(& ' 1.2(9 is an ideal system.

LC= based cementation may pro!ide successful solution.

Elend of fibers in cement slurry may gi!e most effecti!e

sealing of fracture formation

0%

:nno!ati!e Lost Circulation Plug to rill

successfully 12 Z4 hole" Practical#olutions


210/372

01%

:nno!ati!e lost circulation

materialLi,uid of low !iscosity61&-12cp9/panded 8-> times

#et mass is lighter than water :nert to acid and al)ali specific gra!ity-1.&8


211/372

011


212/372

FO


213/372

=OL# @O1" C'# 1&&P#:5 2" C'# (&& P#: and $" C'# 3(&P#:

1 2 $

s'g 1.1 1.$ 1.*

01A

FO


214/372

< E C

01B

C=@+ #L%RRT :@ W


215/372

R" Foam cement slurry

of 1.13 s. g

01

Ch-:

MUD LOSS #R&*&NTIONROM DRILLIN7 LUID&N7IN&&RIN7 #OINT O *I&4


216/372

&N7IN&&RIN7 #OINT O *I&4

218

#R&*&NTION O MUD LOSS

Pre!ention is better than cure

+wo aspects of pre!ention are


217/372

1. Formation strengthening-for wea) formation

2. #ub hydrostatic fluids - for low formation pressure

01=

Pre-re,uisites of formation strengthening

concept are "

1. Fracture strength of the roc) by lea) off test

#R&*&NTION O MUD LOSS (Contd!


218/372

g y

6LO+9 or pressure integrity test6P:+9.

2. Pore pressure of formation.

01

Causes of low !alues of fracture strength are"

1. Poor cementing ' binding material between

roc) grains or matri/



219/372

roc) grains or matri/

2. =icro fractures in the roc) matri/

$. Roc) fluid interaction

01

#trength of wea) formations can be increased

by"

1. Formation sealing materials

2 #ystem loss circulation materials



220/372

2. #ystem loss circulation materials

$. @on in!asi!e fluids

*. Cement s,ueeing

00%

1.Formation sealing materials

+hese materials are"



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1. #ulphonated asphalt

2. Gilsonite

001

Sulphonated asphalt

:t seals micro-fractures.


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pp p g

:t strengthens wea) formations and pre!ents

losses in such formations.

:t stabilies borehole shale #tability.

000

7ilsonite

:t is a mineral which seals micro-fractures.

:t stabilies and plasters borehole walls.

:t strengthens the wea) formations and



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g

pre!ents losses.

osages !ary from 2-8 lbs'bbl.

00A

2. S.ste, lost ci"culation ,ate"ials (LCM!

#pecially selected sied particulate matter.

Particle sie distribution is based on e/pected



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width of largest fracture.


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p

+hey pre!ent or minimie losses.

00

Co,,onl. used s.ste, LCMs a"e :

1. #ied Calcium Carbonate Large5 =edium5



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Fine and =icronied

2. Graphite

$. #ied olomite Lime #tone

00>

SiEed Calciu, Ca"/onate

< blend of calcium carbonate particles of

different micron sies.



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Preferred to minimie or pre!ent losses in

limestone reser!oirs

Can be subse,uently remo!ed by acidisation.

00=

7"aphite po


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Eridge seals the pore throats and micro

fracture and helps pre!ent the mud loss.

00

7"aphite po


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plimestone reser!oirs.

Can be subse,uently remo!ed by acidisation.

0A%

$. Non In$asi$e luids

@o!el concept based on drilling fluidformulation with almost ero in!asion in the

formation



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formation.

Propriety compositions which create an

imper!ious barrier within the formation.

0A1

Non In$asi$e luids

Earrier stops further in!asion of the fluid

phase



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/erts entire confining pressure of the drilling

fluid on to the well bore.

nhancement of LO+ !alue. 0A0

Non In$asi$e luid

=ay be used to increase LO+ !alue before

increasing mud density.

P t d l d t i t



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Pre!ents mud loss and sa!es e/tra casing to

co!er transition one.


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formation.

nhances the strength of the formation.

0A>


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SU-'@DROSTTIC DRILLIN7 LUIDS

ensity of drilling fluid is less than that of

water is called #ub hydrostatic drilling fluid.

Reser!oir formations ha!e become sub



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Reser!oir formations ha!e become sub-

hydrostatic due to pressure depletion

Pre!ent mud losses in these formations.

0A

*a"ious options of su/ h.d"ostatic d"illing fluids a"e:

1.


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*. %nder balanced drilling ' =anaged Pressure

drilling 6%E ' =P9

(. =icro Eubbles Proect under Progress by :+

0A

i"; Co,p"essed gas "e5ui"e,ents

1. #pecial drilling infra structure.2. Aard and impermeable formations.$. @o influ/ of water or any other fluid in the

well bore



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well bore.

*. nough precautions for possible fire haardor e/plosion.

(. Protection from corrosion.

0B%

oa, ;Sta/le oa,

+he application re,uirements are"

1. #pecial drilling infrastructure.

2. #pecial additi!es for foam generation and



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p g

stabilisation.$. Problems of foam disposal

*. Aandling problems of fluid influ/

0B1


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243/372

'ollo< 7lass Sphe"es ('7S!

asy to prepare and maintain drilling fluidwith AG#

@o ad!erse effect on mud properties



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@o ad!erse effect on mud properties

@o special infrastructure re,uired for its

application

0BB

'ollo< 7lass Sphe"es ('7S!

asy handling and storage



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@on abrasi!e

@on corrosi!e0B

'7S pplication in ON7C

1. First field trial in drilling fluid is carried out on

well :P1&A and :P11Ain western offshore

by maintaining the mud weight ;.$-3.& ppg.

2. +hree types of sub-hydrostatic drilling fluids



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yp y g

designed by :+ using AG# for =umbaiAigh


247/372

*.+he designed drilling fluids of density ;.(ppg showed good rheological and filtration

properties. oses is !arries from 2(-$&.

0B=


(. +he AG# based sub hydrostatic drilling fluidhas shown retention of specific gra!ity e!enafter application of *&&& psi pressure at >& cfor 3 hours



248/372

for 3 hours.

8. +he sub-hydrostatic wor) o!er fluid up to#.G. &.8( was also designed using hollowglass spheres.

0B


;. =any assets and basins ha!e shown )eeninterest in sub-hydrostatic drilling and wor)o!er fluids for field application in their areas.



249/372

3. +hese sub hydrostatic fluids are e/pected topre!ent mud losses in wea) and depletedformations.

0B


>. +hese fluids are also e/pected to minimie

formation damage and shall enhanceproducti!ity of the reser!oir.



250/372

1&. +he sub hydrostatic wor) o!er fluids shallpre!ent losses during well completions and

wor) o!er operations

0%

Unde" alanced D"illing (UD! ; Managed#"essu"e D"illing (M#D!

Pressure of the mud column is less thanformation pressure

#pecial drilling infrastructure re,uired



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p g ,

@o chance of inducing fracture +otal control and monitoring of well bore

pressures Problem of mud loss eliminated

01

Mic"o u//les /ased d"illing fluids

Concept to formulate the drilling fluid to beused in drilling and mitigate the mud losscomplication in depleted Reser!oir ' mud lossprone area.



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Formulation of stabilied micro-bubbles baseddrilling fluids to control mud loss

00


#table micro-bubbles can be created with thehelp of certain surfactants and Polymers.

+emperature stability of =icro-bubble is



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p y

11&deg.C.

Pressure stability of =icro-bubble is *&&&psi

Aa!ing non damaging Characteristic. 0A


=icro-bubbles is more stable and consists ofsurfactant tri layer.

1.


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p y

!iscous water shell.

2.


255/372

2. Restoring circulation ' Controlling mud loss

0

Methods fo" locating the Eone of ,ud loss

a"e:

1. #pinner sur!ey

2. +emperature sur!ey

D&T&CTION ;LOCTIN7 MUD LOSS +ON& (Contd!


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$. Radioacti!e sur!ey*. +he hot wire sur!ey

(. Pressure transducer sur!ey

0>

1 Spinne" su"$e.

. =ade by running a small spinner attachmenton a single conductor cable

. Rotor will spin or turn if there is anyhoriontal motion of mud

. +he motion of rotor is recorded on film as a



257/372

series of dashes. +here is a definite speed up of rotor at the

point of loss

0=

Li,itations of Spinne" su"$e.

Re,uires deliberate loss of large !olume of

mud

@ot effecti!e where sealing material is already



258/372

present in mud

0

2. Te,pe"atu"e su"$e.

epends on subsurface thermometer formeasuring difference in mud temperature andformation temperature



259/372

Recorded by running a sensiti!e element inhole5 obser!ing resistance change withrespect to temperature

0

2. Te,pe"atu"e su"$e.

+wo sur!eys are run.

One for temperature gradient of well.



260/372

Other5 after adding cool mud.

#harp temperature change will occur

at loss point.0>%


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B 'ot


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resistance is noted

=ud is pumped into the hole

0>0

B 'ot


263/372

:f resistance does not change5 tool is below

the point of loss

0>A

#"essu"e t"ansduce" su"$e.

:nstrument composed of hollow cylinder withan entrance at the top5 larger in cross sectionthan the e/it at the bottom

+he geometry of instrument restricts the flow



264/372

of mud through the cylinder < window fitted with a neoprene diaphragm on

one side of the cylinder

0>B


< mo!able electrode on the diaphragm mo!esbac) and forth between two fi/ed electrode



265/372

+he potential difference5 indicati!e of rate offlow of mud5 between mo!able and fi/ed

electrode is measured at the surface

0>



266/372

:t is simple in construction and operation :t is not easily clogged by lost circulation

material

0>>


:t is wor)able in almost any type of mud :t can be used to locate a hole inside the casing.

Li,itations of #"essu"e T"ansduce" Su"$e.



267/372

.

Considerable mud flow is re,uired

+he e,uipment may not be readily a!ailable

0>=

Ch->:

MUD LOSS CONTROL

ROM DRILLIN7 LUID&N7IN&&RIN7 #OINT O *I&4


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283

Loss Ci"culation Cont"ol Mate"ials"

Eridging


269/372

OE 6diesel oilKbentonite9 plugs own hole mi/ed Aard plug

OEC 6diesel oilK bentonite K cement9

0>

"idging agents in ,ud

=aterials used to ma)e loss control pills ands,ueeed into the thief one

Eridging materials form an effecti!e e/ternal

Cont"olling Mud Loss (Contd!


270/372

as well as internal seal in the loss one +his reduces or cures the mud loss.

0=%

"idging agents in ,ud ; #ill

Eridging material is of three types"

1. Granular"Wall nut shell5 Coco nut shell andCalcium Carbonate5 #ulphonated


271/372

2.Fibrous" #aw dust5 Rice Aush etc.

$. Fla)y" =ica Fla)es0=1


:t is always desirable to use a blend of two or

more different types of bridging material toform an effecti!e seal.

+he choice of bridging material depends on

CONTROLLIN7 MUD LOSS (Contd!


272/372

the type of formation in which mud loss occursand also the se!erity of mud loss

0=0


< blend of fla)y 5 fibrous and granular bridging

material is recommended for unconsolidatedformations.

< blend of fla)y and fibrous bridging material isrecommended for highly permeable formations< bl d f fib d l b id i



273/372

< blend of fibrous and granular bridgingmaterial is recommended for mud loss infractured formation.

0=A


Proper sie and types should be mi/ed indrilling fluid for s,ueeing into loss one.

+he total concentration of bridging agent

h ld b b t 2& t (&PPE 6lb 'Ebl9



274/372

should be between 2& to (&PPE 6lbs'Ebl9 %se open end drill pipe to accommodate all

types of sies of the bridging materials.

0=B

"idging agents

=ica fla)es

Walnut hulls

Cotton seed hulls



275/372

#aw dust

Rice hus)

Eagasse0=

"idging agents

Cellophane fla)es

Leather fla)es Ground plastic =arble chips Gilsonite

+h t bb



276/372

+hermo set rubber

'igh filte" loss slu"".

Pill of the material slurry pumped in the oneof mud loss. .g. Aigh !iscous GelKLime

#lurry losses all its fluid phase to the

formations adacent to the loss one



277/372

formations adacent to the loss one Remaining solid mass forms a tough and

effecti!e seal in the loss one

0==

Do


278/372

with water and the Eentonite powder swells toform a thic) and soft plug within the loss one

to pre!ent further loss.

0=

Do


279/372

loss one One such soft plug is prepared by mi/ing high

percentage of bentonite in diesel oil

0=

Do


280/372

these plugs is generally 1"1 or 1"2.

mud loss course powerpoint-rjy-11 feb 2013

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