Schlumberger Reservoir Completions
PerforatingA General
Overview
2 Perforating
8/5/99
Perforating
The productivity of a given reservoir is primarily
dependent on the near wellbore pressure drop.
This is governed by drilling damage and perforation
parameters.
Furthermore, successful stimulation and sand control
operations are strongly dependent on perforation
parameters.
3 Perforating
8/5/99
Perforating
Today we will look at:
History
Physics
Factors affecting performance
Quality Control
4 Perforating
8/5/99
History
Mechanical, prior to 1932.
Bullet Gun, 1932 to present
Hydraulic, 1958 to present
Abrasive jetting
Shaped Charge, 1946 to present
Spin-off from DOD and DOE Technology
Most popular
5 Perforating
8/5/99
Cavity Effect
6 Perforating
8/5/99
Shaped Charge Perforator
7 Perforating
8/5/99
The Perforation Process
High velocity - 7,000 m/sec
High Pressure - millions psi
High speed - microseconds
Low temperature
Particulated jet does the
work
8 Perforating
8/5/99
Shaped Charge Magic
9 Perforating
8/5/99
Penetration Physics
Jet Length
Jet Density
Jet Velocity
Jet Mass
10 Perforating
8/5/99
Penetration Physics
11 Perforating
8/5/99
Requirements:
Performance
Penetration Depth, Casing Hole Diameter
Flow effectiveness or productivity
Consistency
Manufacturability
Ease and Consistency
Cost
Effective
Competitive
Shaped Charge Perforators
12 Perforating
8/5/99
Solid copper (1946)
Adapted from military
Used today in big hole charges
Form large slug
Bimetallic sheet metal (1958)
Hard to fabricate
Poor performance
Powder metal (1960s)
Slug disintegrates
Preferred liner for deep penetrators
Shaped Charge Liners
13 Perforating
8/5/99
Factors Affecting Charge
Performance
Symmetry - Symmetry - Symmetry
A Shaped Charge is at best a semi-stable
device and any deviation to the design that
upsets its symmetry will yield a crooked jet and
thus reduced performance.
14 Perforating
8/5/99
Consistent manufacturing
Liner
Powders and pressing
Tooling
QC Testing
API type targets
Regular checking
Aggressive QC is critical for consistent shaped
charge performance
Factors Affecting Charge
Performance
15 Perforating
8/5/99
Effect of Optimized Liner Design
Perforating Gun Comparison
0 5 10 15 20 25 30 35 40 45 50 55 60
Old System
HyperJet
Ultrajet
PowerJet
G
u
n
T
y
p
e
API Section I Penetration (inches)
54.1 in.
47.3 in.
34.6 in.
25.0 in.
1999
16 Perforating
8/5/99
Factors Affect Perforation
Performance
Water Standoff
Scallop/Port Plug Thickness
Shot Density/Charge
Packaging
Target Properties
17 Perforating
8/5/99
Factors Affecting Performance
18 Perforating
8/5/99
Standoff (distance from charge to gun wall)
Can optimize charge performance.
Scallop/port plug thickness
Very small effect on deep penetrator.
More effect on big hole.
Charge packaging in the gun
Charge-to-charge interference.
Detonating cord-to-charge interference
It is a SYSTEM design
Gun Design Factors Affecting
Charge Performance
19 Perforating
8/5/99
Major effects
Gun clearance
Casing and formation strength
Effective formation stress
Wellbore Fluid
Temperature (selection of explosive)
Downhole Parameters That Affect
Performance
20 Perforating
8/5/99
Perforator Performance vs. Gun
Clearance
Penetration
Little effect in most conditions
If the ratio of wellbore clearance over charge
diameter is >2 then EH and Pen could be
reduced by a factor of 0.6 to 0.75. A ratio of 1 is
OK.
very large standoff deteriorates jet
Entrance hole
Effect can be considerable
BH guns are optimized to shoot with standoff
41 Perforating
8/5/99
Temperature
Selection of explosives:
T (within rating) --> no performance loss
Effect is cumulative
Consider accuracy of T reading
Ratings
Temperature: RDX < HMX < HNS/HTX
Performance: HNS <HTX< RDX < HMX
42 Perforating
8/5/99
Time vs Temperature
43 Perforating
8/5/99
Temperature
Major effects:
If T rating is exceeded:
Loss of performance
Burn
Low order or autodetonate
HMX or RDX < 300 F will not autodetonate
Above 300 F might burn or autodetonate
HNS/HTX is not known to autodetonate
Might lose performance or burn
44 Perforating
8/5/99
HMX Enerjet
300
310
320
330
340
350
360
370
380
390
400
0.1 1 10
Time to Autodetonation, Hours
T
e
m
p
e
r
a
t
u
r
e
,
F
0.2% max RDX
Rating point
45 Perforating
8/5/99
HMX and T > 330 F
HMX at 330 F has a phase change which increases
its impact sensitivity
If unshot guns need to be pulled from the well:
For 48 hrs do not download guns
After 48 hrs HMX reverts enough to be safe to handle
46 Perforating
8/5/99
Classifications of Perforating Gun
Systems
Through-Tubing
Small guns to get through the tubing string
Can be shot underbalance
Casing
Larger guns with big charges
Usually shot overbalance
High Shot Density
Larger gun with more shots per foot
Used for tubing conveyed applications
47 Perforating
8/5/99
Another Classification of Gun
Systems
Capsule Charge
Enerjet (1
11
/16, 2
1
/8 , 2
1
/2 -in. )
Pivot Gun (1
11
/16 -in.)
Hollow Carrier
Scallop Guns (1
11
/16 & 2
1
/8-in.)
HEGS (3
1
/8 & 4-in.)
Port Plug Guns (4-in.)
HSD (1.56 to 7-in.)
