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Completion Packers

This article describe the completion packer selection, specifications, classification, setting

mechanism, etc.

Packer selection/specification

packer selection must take into account:

type of hole: open, cased, liner completed;

type of well: producing, appraisal, injection;

well content: oil, gas sweet, sour!, water, steam, abrasi"e material;

natural well pressure: high, low, flowing, shut#in # in the tubing;

imposed well pressure: high, low # in the annulus # especially during completion pressure

testing;

well temperature: flowing, shut#in # range of temperature changes;

"ertical: straight, de"iated # small angle, large angle; $production method: natural flow, gas lift,

pump;

drawdown rate: high, low;

completion method: tubing latched in tension, setdown in compression, multiple straddle pack,

tailpipe, e%tension re&uired below packer;

tubing hanger design: suitable for packer setting/releasing method;

minimum bore: ability to pass tools and e&uipment re&uired further downhole;

packer function: annulus/tubing isolation, 'one isolation, damage straddling, cement

s&uee'ing;

also to be taken into consideration are the pressure and temperature changes, especially

during stimulation operations;

casing damage caused by the slips;

hang#off re&uirements tailpipe assembly!.

Packer classification

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Retrievable:

The packer is run as an integral part of the tubing. (%cept for the retrie"able bridge plug, the tubing

cannot be pulled without pulling the packer. The packer is set mechanically, hydraulically or a

combination of both. )t is released by manipulation of the tubing, either rotating or pulling shearing

lock pins!. *enerally used where the well may ha"e to be worked o"er regularly i.e. electrical

submersible pump applications!, temporary completions i.e. production testing! or well inter"ention

acti"ities i.e. stimulation or casing leak detection!.

$The following aspects need to be considered when running retrie"able packers:

#pulling the packer out of the well may swab the well in;

#e&ualisation of pressure across the packer before pulling may be difficult care should be e%ercised on

shallow set during unseating operations!;

#straight pull release packers may prematurely shear and release due to tubing contraction;

#deposits abo"e the packer may render it non#retrie"able.

Permanent:

The packer is set within the casing and the setting mechanism tubing/wireline! can be released from

the packer. (%cept for the case of a permanent bridge plug the tubing can be run and resealed in the

packer. The packer may be set mechanically by tubing!, hydraulically or electrically by wireline!. +s

the name implies it cannot be retrie"ed, but can be destructi"ely remo"ed i.e. milling!. generally used

in high pressure differential applications.

$Permanent/etrie"able: This class of packer combines the ad"antages of the permanent packer i.e.

large bore, withstands higher pressure differentials etc.! but when re&uired can be released and

reco"ered, entire, from the well.

)n general, a permanent packer will be selected if:

$the predicted ma%imum differential pressure across the packer e%ceeds - psi;

$the temperature at setting depth e%ceeds -01;

$23 is present and the temperature at the packer is less than 4501;

$infre&uent worko"ers are en"isaged.

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6therwise a retrie"able packer may be recommended.

Packer setting

Mechanically

The packer may be set by one or combination of: $rotation standard 787 slot latch arrangement!;

$compression slacking of the tubing weight into the packer; $tension pulling, o"erweight, up on the

packer!.

Hydraulically

The packer is set by applying pressure to the tubing so as to cause a pressure differential between the

tubing and annulus. Commonly used in deep or highly de"iated wells, or offshore en"ironments when

the platform motion plays a significant role. )t is also a consideration if control lines are used with the

subsurface safety "al"e or permanent downhole monitoring applications.

Electrically

The packer is set by a setting tool on electric wireline wireline set!. The wireline setting tool is

released and reco"ered with the wireline. This method is more commonly employed for setting bridge

plugs or when the e%act location of the packer is critical.

Packer bore$9o bore # bridge plugs. To isolate the casing or tubing. 3ometimes referred as cement retainers.

$3ingle bore # for use with a single conduit.

$ual bore # for use with two conduits in dual completions.

Packer forces

There are two prime forces acting on a packer:

$hydraulic pressure forces differential pressure acting !

$tubing#to#packer forces.

The tubing#to#packer forces need to be calculated at the design stage.

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1orce needed to pre"ent unseating. Permanent packers will withstand pressure differentials from

abo"e and below. etrie"able packers may be either compression set, tension set or both.

The assumptions and actual tubing set#down force need to be documented to pre"ent mishaps during

subse&uent well inter"ention acti"ities

6perating en"elopes safe performance window!

The permanent packer rating en"elope is a means of describing the functional limits of a packer under

combined pressure and applied a%ial tensile/compressi"e! loading. hen re&uesting an en"elope for

a permanent packer, specify the packer model, si'e, material and casing si'e. The ratings deri"ed from

en"elope graphs are for unplugged packers. Plugged packer ratings can be significantly lower.

ecommendations

$3elect a packer with element metal shoe and shoe support systems metallic back#up rings!

in high#pressure applications to pro"ide anti#e%trusion back#up for the elements.

$Typical packer element combination is a