Methods of Perforating
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.
Shaped Charges
Shaped Charges
Explosive Powder
Chemical
compound
RDX
HMX
PYX
Charge Liners
Shaped Charge
Types of Perforators
Body copy for slides
Wireline Casing Guns
Advantage
Large O.D. guns with large charges for
maximum performance
Perforating cost may be lower that other
methods
Disadvantages
Perforating must be done in balanced or
overbalanced conditions for safety
Perforator length is limited to lubricator
length
Wireline Casing Gun (cont.)
Disadvantages (cont.)
Well control is dependent on lubricator
sealing system
Well deviation increases time and
difficulty in perforating
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
Through Tubing Perforating (cont.)
Disadvantages
Small O.D. guns with small charges
have limited performance
Guns are often decentralized to
optimize performance
Underbalance generally limited to
1000 psi
Perforator length limited to lubricator
length
Through Tubing Perforating (cont.)
Disadvantages
Surface well control limited by
lubricator seal system
Underbalance only available on first
run in well
Wire may be difficult to maintain seal
while pulling out of hole
Special pressure sealing equipment is
necessary when SITP is high
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 nonelectric detonators and no fire devices
Tubing Conveyed Perforating
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
Tubing Conveyed Perforating
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.
What You Want
What You Get
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
Getting What You Want
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
Getting What You Want
A Typical
Tubing
Conveyed
Overbalanced
Perforating
Well
Configuration
Gas And /Or Liquid Pumpers
Gas Pressure In Wellbore
Liquid Over Perforation Interval
Pay Zone
Damaged Zone
Getting What You Want
Power Perf
Provides scouring agent (bauxite) near
the perforations
Pumping during/immediately after
perforating 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
Getting What You Want
Power Perf
Proppant Placement
Proppant is displaced by
Nitrogen and fluid into
formation following detonation.
Small tubing punch charges
allow Proppant to leave carrier
but fail to damage other
tubular.
Getting What You Want
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
Getting What You Want
StimGun
Assembly
TM
Conventional
Perforating
Carrier
System
Modified
Charge
Designs
Outer Propellant
Cylinder Designed to
Break in Known Sections
Getting What You Want
Preparing the StimGun
StimGun
The propellant is positioned
and fired over the
completion interval.
As the propellant burns it
produces a pressure load
on the formation below the
formation rocks
compressive yield strength.
Getting What You Want
StimGun
As the propellant burn pressure
increases strain energy is
accumulated in the rock matrix
until the circumferential stress
around the wellbore exceeds
the strength of the rock.
At this point fracturing occurs.
Getting What You Want
StimGun
Fracture volume is
increased by continued
gas generation from
the progressive burn
front of the propellant.
Burn duration averages
12 ms.
Questions?
