low pressures to high pressures - how regional ... · low pressures to high pressures - how...
TRANSCRIPT
Richard Swarbrick & Stephen O’Connor
GeoPressure Technology
Finding Petroleum Conference
London: January 2010
Low pressures to high
pressures - how regional
overpressure mapping helps
find trapped hydrocarbons
Principal Messages
• Overpressure mapping is an underutilised
technology
• “Low” overpressure can be highly significant for
reserves determination and unrecognised
potential
• “High” overpressure controls exploration risk for
breached traps
• Regional overpressure mapping projects have
now been completed in NW Europe and in
progress elsewhere
STRESSPRESSURE
RELATIONSHIPS ARE KEY TO PRESSURE
Lateral drainage and pressure regressions
Pressure
De
pth
Shale O/P gradient
(rapid loading)
WaterGas
Water
Pressure
De
pth
Shale O/P gradient
(rapid loading)
WaterGas
Water
Overpressured
Reservoirs
Near Normally
Pressured
RESERVOIR PRESSURE > SHALE PRESSURE
Overpressure
Low Pressure Relationships
• Interpret reservoir pressure data
• Assign overpressure values for each reservoir
• Map overpressures for each reservoir
• If reservoir continuous contour values
• Establish possible hydrodynamic flow directions
• Examine well field data
• Establish tilt on hydrocarbon-water contact
• Revise reserves
38
578083
107 282
48
51
68
61
1519 27
353Forties
27 54 332
58
60
2
17 – Cat 419 – Cat 3
20
13
54093
243336
222
59
119151
183
165
13 – Cat 2
Depleted HC in
wells
No Palaeocene Data
73
Update of CNS (2003) MapDistribution Map of
Overpressures
Forties Formation
Contours of
overpressure in psi
Nelson
Field
Channel Axis
Central Graben
Pressure Study
Distribution Map of
Overpressures
Andrew Formation
Contours of
overpressure in psi
O/P < 50 psi
Hydrodynamic
flow directions
Andrew Sandstone limit
O/P > 2000 psi
Close to shale
pressures?
O/P < 50 psi
EXPLORATION SIGNIFICANCE
Potential to fill to
structural spill point
Hydrostatic
Simple Anticline: Pressure-
Depth plot for oil accumulationOWC/
FWL
Well A
Oil Down To
Upside potential
to spill point
Proven Reserves
30 MMBO
Possible Reserves
+ 30 MMBO
DRY HOLE
Well AAppraisal
Well B
Proven Reserves
40 MMBO
OWC/FWL
DECISION TIME!
Assess reserves – not enough to justify
development
Relinquish acreage?
Farm out/sell assets to smaller/leaner
company?
Examine other possibilities and look at
regional pressure distribution?
DRY HOLE
Well AWell B
Regional overpressure distribution suggests lateral drainage,
with outflow to right
OIL & WATER
Well AWell C
Well B
OWC/FWL
Common Oil Leg
Variable water legs
Hydrodynamic Model
o
o
o
x
x
x
+
+
++
Minimum pressure data to define reserves
o
+
x
Well A
Well B
Well C
OIL & WATER
Well AWell C
Proven Reserves
70 MMBO
Well B
Implications
Hydrodynamic model influences reserves
distribution, volumes and reservoir
connectivity
Hydrodynamic reservoirs are to be found in
many overpressured basins – we just have
not properly looked yet.
GeoPressure Technology, an Ikon Science
company, specialises in identifying
hydrodynamic aquifers (lateral drainage)
High Pressure Relationships
• Interpret well pressure data
• Assign overpressure values for each reservoir
• Map overpressures for each reservoir
• Similar values are in same pressure cell
• Define pressure cell boundaries (not trivial)
• Map aquifer seal capacity/effective stress
• Identify trap leak points and protected traps
• Establish seal breach risk and exploration strategy
after Seldon & Flemings,
2005
PROTECTED TRAP
LEAKING TRAP
after Seldon & Flemings, 2005
PROTECTED TRAP
LEAKING TRAP
Overpressure
AQUIFER SEAL CAPACITY
Minimum
Stress
Aquifer
Gradient
Aquifer Seal
Capacity
Determined
from 2
algorithms
Determined
from RFTs, etc
Structural
Crest
Hydro-
static
Gradient
Hydrocarbon
seal capacity
-500
0
500
1000
1500
2000
2500
30002
2/3
0a
-12
2/2
9-6
s22
3/2
6a
-2
12
2/3
0b
-42
2/2
4b
-83
0/1
c-2
A2
2/2
1-4
22
/21
-73
0/0
1f-
82
2/3
0b
-1
5Z
23
/26
b-8
23
/26
-3
23
/26
b-1
52
2/2
9-7
23
/26
b-1
42
2/0
7a
-22
1/2
0a
-12
2/3
0b
-1
12
2/2
8a
-12
3/2
6-7
23
/16
d-6
29
/5a
-32
2/0
8a
-31
5/3
0-1
2N
O1
/6-
72
2/2
7a
-1
30
/1c-4
29
/4a
-22
2/2
5b
-2
29
/05
b-4
ZN
O7
/7-
22
2/2
3b
-62
9/5
a-5
29
/08
b-5
22
/30
a-2
22
/22
b-4
21
/25
-1
23
0/0
1c-3
22
/28
a-4
29
/10
a-2
22
/24
d-1
02
9/2
a-2
29
/10
-3 s
ti2
2/2
4a
-A1
Z2
2/3
0c-1
02
9/0
9c-4
29
/05
a-1
Z2
3/2
6-2
29
/08
a-3
15
/23
a-1
22
2/3
0a
-6
22
/24
-72
2/2
4a
-23
0/7
a-7
29
/05
b-F
12
1/3
0-3
30
/11
b-3
22
/24
b-9
23
/22
b-4
30
/07
a-P
13
0/0
7a
-8
39
/02
-2
Z2
1/3
0-1
92
2/8
a-4
21
/25
-10
30
/7a
-12
22
/30
c-1
32
9/0
7a
-7
21
/01
a-2
11
5/2
2-1
63
0/0
7a
-6
29
/08
a-4
23
/11
-4N
O3
/4-
12
2/1
8-6
29
/07
a-4
15
/22
-D1
A2
9/0
7a
-5
21
/25
-82
3/2
7-6
30
/11
b-4
22
/30
a-1
62
9/0
7-8
29
/07
-11
15
/27
-1
0
Top
Re
serv
oir
Se
al C
apac
ity
(psi
)
Well
Top Reservoir Seal Capacity
1400 psi
Aquifer Seal Capacity – Top Reservoir (85 wells)
Offers a risking strategy
Low RiskHigh Risk
17 June 2006
Primary Eruption: 29th May + secondary eruption 2nd June 2006
Courtesy of Bakrie Media Centre
Concluding Remarks
• Overpressure mapping is a valuable exploration
tool
• Hydrodynamic systems are not well recognised –
worldwide exploration opportunity
• “High” overpressure represents an exploration
and drilling challenge
• Integration of pressure data into the “finding
petroleum” workflow is key to success
Finding Petroleum Conference
London: January 2010
QUESTIONS