Perforation Methods

7/24/2019 Perforation Methods

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Methods of Perforating


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Bullet Perforators

The first perforating gun; developed in 1932.

Fired a projectile (bullet) through the casing, cement,

and into the formation to create a flow path from the

formation into the casing. Provides very uniform hole in the casing.

Became less effective as well depths required higher

strength casing.

The bullet posed problems with plugging.

Still in limited use today.


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Shaped Charges


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Shaped Charges


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Explosive Powder

Chemical

compound

RDXHMX

PYX


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Charge Liners


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Shaped Charge


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Types of Perforators

Body copy for slides


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Wireline Casing Guns

Advantage

Large O.D. guns with large charges for

maximum performance

Perforating cost may be lower that othermethods

Disadvantages

Perforating must be done in balanced oroverbalanced conditions for safety

Perforator length is limited to lubricator

length


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Wireline Casing Gun (cont.)

Disadvantages(cont.)

Well control is dependent on lubricator

sealing system

Well deviation increases time anddifficulty in perforating


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Through Tubing Perforating

Patented by Exxon in 1953

Patent purchased by Schlumberger

Advantages

Allows limited underbalance to formation Underbalance provides perforation cleanup

Better well control due to packer and tubing

in place during perforating

Packer and completion/DST tools in well

when perforating


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Through Tubing Perforating (cont.)

Disadvantages

Small O.D. guns with small charges

have limited performance

Guns are often decentralized tooptimize performance

Underbalance generally limited to

1000 psi

Perforator length limited to lubricatorlength


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Through Tubing Perforating (cont.)

Disadvantages

Surface well control limited by

lubricator seal system

Underbalance only available on firstrun in well

Wire may be difficult to maintain seal

while pulling out of hole

Special pressure sealing equipment isnecessary when SITP is high


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Tubing Conveyed Perforating

Advantage

Large O.D. guns with large charges for

maximum performance

Optimum well control Unlimited underbalance

No limits on well deviation

No limits on overall length

Surface safety is enhanced by use of non-

electric detonators and no fire devices


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Advantage (cont.)

Guns are fired mechanically or

hydraulically

Can be deployed on conventional tubing,coiled tubing, slickline or wireline

Rig is not always required

Multiple zones can be perforated

selectively

Saves rig cost on long intervals

Multiple completion/test methods can be

utilized


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Disadvantages

Have to change customers perception of

cost from single service cost to overall

completion cost.

Misfires can be more costly to correct if

guns are attached to tubing.

Have to relieve customers safety

concerns.


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What You Want


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What You Get


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Getting What You Want

Underbalance perforating

Use sufficient underbalance to back flush perforating

debris and damage into the tubing and up to surface

Available underbalance is limited to formation pressure Maximum usable underbalance is determined by

formation matrix and mechanical systems of the well

Proper underbalance will maximize production


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Extreme Overbalance Perforating (EOB) Apply extreme overbalance pressure to tubing or

wellbore while firing the perforating gun

Will frac through the perforating damage and damaged

zone into virgin formation

Extreme overbalance pressures range from 1.4 to 2.2

psi/ft

Typical to see the same production results as with

underbalance perforating

More expensive than underbalance perforating


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A Typical

Tubing

ConveyedOverbalanced

Perforating

Well

Configuration

Gas And /Or Liquid Pumpers

Gas Pressure In Wellbore

Liquid Over Perforation Interval

Pay Zone

Damaged Zone


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Power Perf

Provides scouring agent (bauxite) near

the perforations

Pumping during/immediately afterperforating process forces bauxite into

perf tunnels to aid in clean up

Bauxite aids in removal of perforating

debris and compacted zone Normally run in conjunction with EOB

and/or Stimgun


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Power Perf

Proppant Placement

Proppant is displacedby

Nitrogen and fluid intoformation following detonation.

Small tubing punch charges

allow Proppant to leave carrier

but fail to damage othertubular.


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STIMGUN

Propellant sleeve is installed over standard perforating

gun

Sleeve is ignited when guns fire and produces a rapid,large pressure at the perforations

Pressure provides near well bore stimulation creating

fractures throughout the formation

Reduces injection pressures for further stimulation

Can be used in conjunction with EOB and PowerPerf


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Conventional

Perforating

Carrier

System

Modified

Charge

Designs

Outer Propellant

Cylinder Designed to

Break in Known Sections

StimGunTM

Assembly



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Preparing the StimGun


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StimGun

The propellant is positionedand fired over thecompletion interval.

As the propellant burns itproduces a pressure loadon the formation below theformation rocks

compressive yield strength.


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StimGun

As the propellant burn pressureincreases strain energy isaccumulated in the rock matrix

until the circumferential stressaround the wellbore exceedsthe strength of the rock.

At this point fracturing occurs.


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StimGun

Fracture volume isincreased by continuedgas generation from

the progressive burnfront of the propellant.

Burn duration averages12 ms.


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Perforation Methods

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