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