COMPLEX TRAPS: A method for calculating
the chance-weighted value outcomes for a
prospect with multiple trap styles
Ray Young, Steven McIntyre, Mark A. McLane,
David M. Cook, James A. MacKay, and James Gouveia
Rose & Associates, LLP
Houston, Texas
AAPG Annual Meeting
Calgary, Alberta
June 2005
• INTRODUCTION
• SIMPLE TRAP ANALYSIS
• COMPLEX TRAP ANALYSIS
• CONCLUSIONS
A
P10
P90
0.1
1
10
100
MMBOE
B
Chance
0.9
Source
Timing/Migration 0.8
0.7
Reservoir
0.8
Closure
0.7
Containment
Pg =
0.28
Spill Point
A
B
Complex Traps
Complex Traps
Only Top Seal
Required for
Success
Complex Traps
Top Seal and
Fault Seal
Required for
Success
A
t
l
u
Fa
Top Seal and
Fault A Seal
Required
Fau
lt
B
Complex Traps
Top Seal,
Fault A Seal
and Fault B
Seal
Required
Complex Traps
d
Up
ip
Seismically
-Defined
Reservoir
Pinchout
Complex Traps
d
Up
Top Seal
and Fault
Seal
Required
ip
Seismically
-Defined
Reservoir
Pinchout
Complex Traps
d
Up
ip
Top Seal,
Fault Seal
and Lateral
Pinch-out
Seal
Required
Seismically
-Defined
Reservoir
Pinchout
Complex Traps
2D
Seismic
Lines
Full-fold 3D
Seismic
Coverage
Complex Traps
Pclosure High
2D
Seismic
Lines
Full-fold 3D
Seismic
Coverage
Complex Traps
2D
Seismic
Lines
Full-fold 3D
Seismic
Coverage
Pclosure Low
Complex Traps
50’
Fluvial or
Overbank?
Fluvial
0’
40’
Preservoir Lower
Preservoir Higher
• INTRODUCTION
• SIMPLE TRAP ANALYSIS
• COMPLEX TRAP ANALYSIS
• CONCLUSIONS
Simple Traps
Simple Traps
Area, Acres
P90
Simple Traps
Area, Acres
Rec. Yield, BAF
Avg. Net Pay, Ft.
P10
x
P90
x
=
Simple Traps
Chance
0.9
Source
Timing/Migration 0.8
0.8
Reservoir
Closure
0.9
0.6
Containment
Pg =
0.31
P1
P10
P50
P90
P99
0.01
0.1
1
RESOURCES, MMBOE
10
Simple Traps
Pg = 0.31
P1
P10
P50
P90
P99
0.01
0.1
0.5
1
RESOURCES, MMBOE
10
Simple Traps
Pg = 0.31
Pc = Pg x Pmcfs
P1
P10
P50
P70
P90
P99
0.01
0.1
0.5
1
RESOURCES, MMBOE
10
Simple Traps
Commercial Distribution
Pg = 0.31
Pc = Pg x Pmcfs
Pc = 0.31 x 0.70
P1
Pc = 0.22
P10
P50
P70
P90
P99
0.01
0.1
0.5
1
RESOURCES, MMBOE
10
Expected Value =
Chance-weighted value of success
+ Chance-weighted value of failure
EV = (Pc X PVc) + (Pf X PVf)
Expected Value =
Chance-weighted value of success
+ Chance-weighted value of failure
EV = (Pc X PVc) + (Pf X PVf)
(Mean Resources X Oil Price) – (Costs + Taxes)
Expected Value =
Chance-weighted value of success
+ Chance-weighted value of failure
EV = (Pc X PVc) + (Pf X PVf)
1-Pc
Expected Value =
Chance-weighted value of success
+ Chance-weighted value of failure
EV = (Pc X PVc) + (Pf X PVf)
Net After-Tax Failure Cost
• INTRODUCTION
• SIMPLE TRAP ANALYSIS
• COMPLEX TRAP ANALYSIS
• CONCLUSIONS
Complex Traps
Options:
• Use Pg of the four-way closure
Complex Traps
Options:
• Use Pg of the four-way closure
• Use Pg of the three-way closure
Complex Traps
P50
Options:
• Use Pg of the four-way closure
• Use Pg of the three-way closure
• Use Pg of the prospect at P50 area
Complex Traps
P50
Options:
• Use Pg of the four-way closure
• Use Pg of the three-way closure
• Use Pg of the prospect at P50 area
9
• Combine the chance-weighted resource
of each of the trapping styles
Complex Traps
For the following example,
let’s assume Reserves are
proportional to Trap area and
fill…
TS: Top Seal = 0.80
P70
Complex Traps
FS: Fault Seal = 0.50
M:
R:
C:
TS:
FS:
P10
Migration
Reservoir
Closure
Top Seal
Fault Seal
0.9
0.6
0.7
0.8
0.5
Resources
P10
P50
MMBOE
P70
original
0.40
MCFS P90
P50
3.80
P10 36.00
Mean 13.20
PV / BOE
truncated
0.80
4.70
36.90
14.40
-2.00
2.50
4.00
3.25
Complex Traps
If the top & fault seals work;
entire distribution is used
P70
MCFS
Complex Traps
If only the 4-way
works, P70 of
1.5 MMBOE
becomes the P1
If the top & fault seals work;
entire distribution is used
P70
MCFS
Complex Traps
If only the 4-way
works, P70 of
1.5 MMBOE
becomes the P1
If the top & fault seals work;
entire distribution is used
P36
P70
P90
Apply MCFS
MCFS
Complex Traps
EV1 = (Pc)(Mean Tr. Res.)(PV/BOE) - (1-Pc)(PV Failure)
(0.30)(0.90)(14.4)($3.25)
- (0.73) ($4.00)
=
$ 9.70 MM
EV2 = (Pc)(Mean Tr. Res.)(PV/BOE) – (1-Pc)(PV Failure)
(0.15)(0.90)(14.4)($3.25)
- (0.865) ($4.00)
=
$2.86 MM
Ignores: Variable Pg, variable PV/BOE,
negative value outcomes
M:
R:
C:
TS:
FS:
Migration
Reservoir
Closure
Top Seal
Fault Seal
Complex Traps
0.9
0.6
0.7
0.8
0.5
P90
4-Way &
Fault Trap
FS
Work
FS
Fails
TS
Work
M, R & C
Work
TS
Fails
M, R or C
Failure
P50
P10
0.3
0.4
0.3
Commercial Failure
0.3
P90
4-Way Only
0.4
P50
0.3
P10
Commercial Failure
Geologic Failure
Geologic Failure
M, R &
C Work
0.378
0.622
0.6220
-4.00
EV, $MM
PV/BOE
0.9
0.6
0.7
0.8
0.5
Trunc. Res.
MMBOE
Migration
Reservoir
Closure
Top Seal
Fault Seal
Probability
M:
R:
C:
TS:
FS:
TS
Work
M, R &
C Work
0.378
0.622
0.6220
-4.00
EV, $MM
PV/BOE
0.9
0.6
0.7
0.8
0.5
Trunc. Res.
MMBOE
Migration
Reservoir
Closure
Top Seal
Fault Seal
Probability
M:
R:
C:
TS:
FS:
PV/BOE
EV, $MM
0.9
0.6
0.7
0.8
0.5
Trunc. Res.
MMBOE
Migration
Reservoir
Closure
Top Seal
Fault Seal
Probability
M:
R:
C:
TS:
FS:
0.0756
-4.00
-0.30
0.6220
-4.00
-2.49
FS
Work
TS
Work
M, R &
C Work
0.378
0.622
0.8
0.2
PV/BOE
EV, $MM
0.9
0.6
0.7
0.8
0.5 Truncations
Trunc. Res.
MMBOE
Migration
Reservoir
Closure
Top Seal
Fault Seal
Probability
M:
R:
C:
TS:
FS:
0.0968
-4.00
-0.39
0.0756
-4.00
-0.30
0.6220
-4.00
-2.49
FS
Work
0.5
TS
Work
M, R &
C Work
0.378
0.622
0.8
0.5
4-way
0.36 only
0.64
0.2
EV, $MM
PV/BOE
0.9
0.6
0.7
0.8
0.5 Truncations
Trunc. Res.
MMBOE
Migration
Reservoir
Closure
Top Seal
Fault Seal
Probability
M:
R:
C:
TS:
FS:
FS
Work
0.5
TS
Work
M, R &
C Work
0.378
0.622
0.8
0.5
4-way
0.36 only
0.64
0.2
P90
0.3 0.0163
0.43 -2.00
-0.00
P50
0.4 0.0218
0.48 -2.00
-0.02
P10
0.3 0.0163
1.01
0.75
0.01
0.0968
-4.00
-0.39
0.0756
-4.00
-0.30
0.6220
-4.00
-2.49
FS
Work
TS
Work
M, R &
C Work
0.378
0.622
0.8
EV, $MM
0.9
0.5
0.1
0.5
4-way
0.36 only
0.64
0.2
PV/BOE
0.9
0.6
0.7
0.8
0.5 Truncations
Trunc. Res.
MMBOE
Migration
Reservoir
Closure
Top Seal
Fault Seal
Probability
M:
R:
C:
TS:
FS:
0.0150
P90
0.3 0.0163
-4.00
0.43 -2.00
P50
0.4 0.0218
0.48 -2.00
P10
0.3 0.0163
1.01
-0.06
-0.00
-0.02
0.75
0.01
0.0968
-4.00
-0.39
0.0756
-4.00
-0.30
0.6220
-4.00
-2.49
TS
Work
M, R &
C Work
0.378
0.622
0.8
0.5
0.1
0.5
4-way
0.36 only
0.64
0.2
EV, $MM
PV/BOE
0.9
0.6
0.7
0.8
0.5 Truncations
4-way &
FS
0.9 fault trap
Work
Trunc. Res.
MMBOE
Migration
Reservoir
Closure
Top Seal
Fault Seal
Probability
M:
R:
C:
TS:
FS:
P90
0.3 0.0408
0.80 -2.00
-0.07
P50
0.4 0.0544
4.70
2.50
0.64
P10
0.3 0.0408 39.60
4.00
6.47
-0.06
-0.00
P90
0.3 0.0163
-4.00
0.43 -2.00
P50
0.4 0.0218
0.48 -2.00
-0.02
P10
0.3 0.0163
1.01
0.75
0.01
0.0968
-4.00
-0.39
0.0756
-4.00
-0.30
0.6220
-4.00
-2.49
0.0150
Sum 1.0000
Math check: Probabilities
sum to 1.00
TS
Work
M, R &
C Work
0.378
0.622
0.8
0.5
0.1
0.5
4-way
0.36 only
0.64
0.2
EV, $MM
PV/BOE
0.9
0.6
0.7
0.8
0.5 Truncations
4-way &
FS
0.9 fault trap
Work
Trunc. Res.
MMBOE
Migration
Reservoir
Closure
Top Seal
Fault Seal
Probability
M:
R:
C:
TS:
FS:
P90
0.3 0.0408
0.80 -2.00
P50
0.4 0.0544
4.70
2.50
0.64
P10
0.3 0.0408 39.60
4.00
6.47
-0.06
-0.00
-0.02
0.0150
P90
0.3 0.0163
-4.00
0.43 -2.00
P50
0.4 0.0218
0.48 -2.00
P10
0.3 0.0163
1.01
-0.07
0.75
0.01
0.0968
-4.00
-0.39
0.0756
-4.00
-0.30
0.6220
-4.00
-2.49
3.79
Sum 1.0000
CHANCE-WEIGHTED TRUNCATED MEAN RESOURCES
Pc = 0.27
Pc = 0.19
MMBO
Pc=0.135
Complex Traps
If only the 4-way
works, P70 of
1.5 MMBOE
becomes the P1
Amalgamated
Complex Trap
MCFS
9
Complex Traps
0%
% chance
CT element
works
30%
70%
100%
Productive area updip of
first complex trap (CT) element
at P70 of total trap area
Area
• INTRODUCTION
• SIMPLE TRAP ANALYSIS
• COMPLEX TRAP ANALYSIS
• CONCLUSIONS
CONCLUSIONS
1. A complex trap is any trap where
the Pg varies across the prospect
and hence the resource distribution
CONCLUSIONS
2. Using the higher Pg will overestimate
the chance of success in a complex trap.
Using the lower Pg will underestimate
the chance of success.
Using the Pg at the P50 area
will reduce the error
CONCLUSIONS
3. The correct way to analyze a complex trap
is to combine the chance – weighted
Distribution of each of the trapping styles.
Failure to do this could have a profound
effect on the estimated prospect value.
COMPLEX TRAPS: A method for calculating
the chance-weighted value outcomes for a
prospect with multiple trap styles
Ray Young, Steven McIntyre, Mark A. McLane,
David M. Cook, James A. MacKay, and James Gouveia
Rose & Associates, LLP
Houston, Texas
AAPG Annual Meeting
Calgary, Alberta
June 2005