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Page 1: Pn gz 2014

Classification: Internal 2011-09-06

Earth’s Energy “Golden Zone” :

A history and future for petroleum exploration

Paul Nadeau

Dept. Petroleum Engineering

University of Stavanger

PET500

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Clay Diagenesis in Shales/Mudstones: Impact on Subsurface Rock-Fluid Systems

• Diagenetic clay precipitation severely reduces permeability

• Main control is temperature, initiating at 60° to 80°C

• At temperatures > 60°C :

• The risk of overpressure development increases

• The probability of hydrocarbon charge increases

• The risk of biodegradtion decreases

• Combined with thermo-chemical rates of quartz cementational porosity loss,

the risk of hard overpressure, seal failure & oil/gas remigration increases

exponentially at temperatures > 120°C

(Buller et al., 2005)

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Smectite / Kaolinite

+ K feldspar

Reactant

dissolution

Illite

precipitation

The Golden Zone Chemical “Seal”

(Nadeau, 2011)

Major permeability reduction due to pervasive pore-bridging illite

> 60oC

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4 Statoil F&T/phn/SOCAR-1/10.00

Modified after: Srodon & Eberl, 1984; Hower et al., 1976; Boles & Franks, 1979; Pearson et al., 1982, Nadeau et al., 1985*.

Clay Diagenesis in Shales: Smectite to Illite vs. Temperature

NB: Reaction onset

is circa 60° to 80°C in

the North Sea and

the Gulf of Mexico

Permeability Reduction

results from nucleation

of circa 0.1 micron clay

minerals in pore-network*

North Sea

Gulf of Mexico

Percent Illite Layers

Tem

pe

ratu

re °

C

0

20

40

60

80

100

120

140

160

180

200

20 40 60 80 100NB: Onset for

Non-Calcareous

Shales may be 60° C

& Calcareous shales

May be 80° C

Tem

pe

ratu

re °

C

Nadeau et al., 2002

SEM North Sea Shales

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Quartz Cementation:

Petrographic Evidence

250 microns

Depth: 2.3 km

Porosity: 30 %Well: 6507/8-4

250 microns

Depth: 4.6 km

Porosity: 10 %Well: 6406/2-7

Statoil INT GEX NO GS /phn 05.03(Buller et al., 2005)

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Quartz Cementation in Sandstones

Mica / Quartz Dissolution

Surfaces

Quartz

grain

Quartz-

Cement

Sequentially coupled Silica

Dissolution Transport &

Precipitation process is :

Precipitation Rate

Controlled

by

TEMPERATURE

&

Pressure Insensitive

Dissolution

Mica / Illite

Mica / Illite

Mica / Illite

Mica / Illite

circa 25% Volume Reduction by

Cementation /

Redistribution

Statoil INT GEX NO GS /phn 05.03(Buller et al., 2005)

(Bjørkum et al., 1998)

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The Golden Zone Chemical “Pump”

(Nadeau, 2011)

c. 40% Ø

c. 25% Ø < 20% Ø

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Quartz Cementation: Porosity Loss Rates vs Temperature

100 160140120

Po

rosit

y L

oss R

ate

s in

% / M

y 2.0

1.5

1.0

0.5

0

Medium Grained

Sandstone

Sandstones

dVqtz

dt= Ae

-E/RT

S( -1) cSiO2

Kqtzx

S = Quartz Surface Area

0.2%/ My at 120 °C

Temperature °C

Quartz Cmt.

Jurassic = 20%

Miocene = <2%

Statoil INT GEX NO GS /phn 05.03

(Walderhaug, 1994;

Bjørkum et al, 1998)

(Buller et al., 2005)

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Classification: Internal

2011-09-06

9

Overpressure Development: A Common Feature

of Sedimentary Basins

HPHT

(Nadeau, 2011)

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0

5,000

10,000

15,000

20,000

Pressure psi

1,000

2,000

3,000

4,000

5,000

6,000

Syn-Rift Fluid Pressure Data:

Jurassic North Sea 35°C

65°C

95°C

125°C

155°C

Lithostatic Gradient

Hydro

sta

tic G

radie

nt

diagenesis

Hydrofracturing &

Oil Remigration

Dep

th m

T

em

pera

ture

°C

ap

pro

xim

ate

Restricted Lateral

Drainage

Statoil INT GEX NO GS /phn 05.03

(70 MPa) (140 MPa)

HPHT

Buller et al., 2005

HPHT

HPHT

HPHT = High

Temperature

High Pressure

Diagenesis & Overpressure Risks > 120°C

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The “Golden Zone” for Oil & Gas Reserves

(Buller et al., 2005)

(Nadeau, 2011)

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The ‘Golden Zone’ Paradigm

• Temperature represents integrated risks for :

• Hydrocarbon charge & Biodegradation

• Reservoir Quality, Overpressure, & Trap & Seal integrity

• Optimal Hydrocarbon Entrapment Efficiency in Basins

• Between 60°C and 120°C i.e. the “Golden Zone”

• The “Golden Zone” is controlled by Geothermal Gradients

• Globally these gradients in Sedimentary Basins are:

• 30°C +/- 10°C per km (P50, P10 & P90)

• The “Golden Zone” is on average 2 km thick (2, 1.5, 3 km)

Bjørkum & Nadeau, 1998; Buller et al., 2005; Nadeau et al., 2005

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Validating The Golden Zone

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Mapping the Golden Zone: Reservoir Data

A Case Study of Planet Earth (Total circa 120,000)

Sources: NPD, DTI, IHS, EUB, MMS, DOE & Univ. OK (after Ehrenberg & Nadeau, 2005)

Gulf of

Mexico

North Sea

Bombay

Reservoirs ¤

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The ‘Golden Zone’: North Viking Graben

270 km

0 km Norway

Troll Gullfaks Statfjord

30 km

10 km

20 km

S

R R R

SE

Modified after Fjeldskaar et al., 2004, Fig. 12.

NW

GZ GZ

60°C isotherm R = Reservoirs

120°C isotherm S = Source Rocks

S

R

Oseberg

Restricted Lateral Drainage

& Pressure Compartments

Due to Basement Faults

HPHT

R

Frigg

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0

1000

2000

3000

4000

5000

6000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

dep

th

(m

)

exploratory wells drilled recoverable hc

0

1000

2000

3000

4000

5000

6000

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

de

pth

(m

)

wells drilled hc recoverable

60°

120°

60°

120°

Exploration Efficiency: Oil & Gas vs. Well Depth

North Sea: 60% Bombay: 10%

30° to

35°C/km

Circa 80°C/km

Cumulative % Exploration well

depth / TVD to 90% of

Resources

Cumulative % Oil + Gas

Base Reservoir Depth

90% of Exploration well

depths

> depth to 90% of Resources

1

2

3

4

5

6

1

2

3

4

5

6

0 0

Golden Zone

Golden Zone

Nadeau et al., 2005

HPHT

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Petroleum Remigration: The Golden Zone Play “Hotel” Model

(Nadeau, 2011)

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Offshore Gulf of Mexico: 12,000 Reservoirs (Nadeau, 2011; Ehrenberg et al., 2008 / Data: MMS, 2003; Seni et al. & Hentz et al., 1997)

(Nadeau, 2011)

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Offshore Gulf of Mexico: Generalized N-S Cross Section

(Nadeau, 2011)

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Gulf of Mexico Shelf Reservoirs:

Temperature vs. Pressure & Field Reservoirs

Tem

peratu

re °

C

Pressure SG

Pressure

Golden Zone

Percent Reservoirs

60

120

90% Oil & 80% Gas

Reservoirs 60°-120°C

HPHT

Ehrenberg et al., 2008, Nadeau et al., 2005

P90, P50, P10

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Classification: Internal

2011-09-06

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Petroleum Remigration & Reservoir Gas/Oil Ratio (GOR)

GB Lectrure MS: Fig. 10

20

40

60

80

100

120

140

160

180

200 Log Reservoir GOR

Reserv

oir

Tem

pera

ture

C

Oil Gas

Gas

Cond.

HPHT

COMPACTION ZONE

EXPULSION ZONE

(Nadeau, 2011)

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Temperature Prediction: The Golden Zone Reservoir Method

(Nadeau, 2011)

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US Gulf of Mexico Estimated Geothermal Gradients: Red = High, Blue = Low

BOEMRE reservoir and NOAA sea-floor temperatures, water depth contour interval 200 m

(Nadeau, 2011)

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Fluid Pressue Probability Plots: US Gulf of Mexico

5%

20%

65%

(Nadeau, 2011)

Page 25: Pn gz 2014

A Golden Zone Exploration Risk Model

Greater Discovered Volumes at

Substantially Reduced Finding Costs

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Global Cumulative Oil Reserves vs. Temperature

0 100 200 300 400 500 600 700

Oil Reserves in BBO

0

20

40

60

80

100

120

140

160

180

200

Tem

pera

ture

°C

0 100 200 300 400 500 600 700

Oil Reserves in BBO

0

20

40

60

80

100

120

140

160

180

200

Tem

pera

ture

°C

12% < 60°C

(0.2% / °C)

85% 60 to 120°C

(1.5% / °C)

3% > 120°C

(0.05% / °C)

Related to the impact of Diagenesis on HC Migration, Trap & Recovery Efficiency.

Nadeau et al., 2005

Golden Zone

Total Recoverable Oil Reserves (proven + probable)

HPHT

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Table 1. Distribution of Global

Conventional Petroleum Reserves

(including condensate)

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Mapping the Earth’s Golden Zone

Integrated map of:

Reservoir temperatures

Total sediment thickness

Surface temperatures & geology

Depth to 60°C isotherm

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Classification: Internal 2011-09-06

The Golden Zone Discovery Process

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Norway: Discovery & Production History

Norway’s Total Discovered

Oil+Gas Reserves=60BBOE

Of which > 50%

Have been produced. (Norwegian Petroleum Directorate, 2006)

Norway Cumulative Discovered and Produced Oil & Gas

0

10000

20000

30000

40000

50000

60000

70000

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Discovery Year

Reco

vera

ble

Reserv

es P

+P

Mm

bo

e

E

S

T+O

OL

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Past Discovery after ExxonMobil (Longwell). Future Discovery extrapolated

The Growing Gap

0

10

20

30

40

50

60

1930 1950 1970 1990 2010 2030 2050

Gb

Past Discovery

Future Discovery

Production

?

Global Oil Reserves: Exploration vs. Production

NB: Discovery rate < 10 Gb/yr

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Present Day Perspective: World Creamed ???

Global Creaming Curve: Oil

y = -8.3805x3 + 49359x2 - 1E+08x + 6E+10

R2 = 0.9953

0

500000

1000000

1500000

2000000

1910 1930 1950 1970 1990 2010 2030

Discovery Year

Cu

mu

lati

ve V

olu

me M

Mb

o

CONTROL: Geology - model predicts limited yet-to-find.

NB. Golden Zone

mainly creamed /

drilled using

rotary drilling tech.

(invented circa 1910)

w/ anticlinal theory

of oil, in the 25 years

after WWII.

Discovery Rate

has Fallen since then

Despite Improved

Technology & Price. WWII

1980 Oil Price Hike

Did not affect

Discovery Rate

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Global Oil Production Scenarios: EIA/USGS, 2005 & Hubbert, 1969

Hubbert, 1969 2100

0

10

20

30

40

50

60

70

80

90

1900 1925 1950 1975 2000 2025 2050 2075 2100

2046

2035

2021

2026

3% Efficiency/Conservation Increase moves Peak Oil 25 years .

NB: after EIA Peak, production drops by Half in less than 10 years !

*

* July, 2008

actual

30

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How Much is 80 Million barrels of Oil / day ?

Global production

is currently circa

80 million barrels

Of Oil per day.

The Suldal River

in W. Norway

flows at a rate

of circa 40 Million

Barrels per day

(circa 75 m3/sec.)

GEX team 18.09.02 Approx. ½ Global Oil Production Rate !

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What do Production Profiles look like ?

Statfjord Field is an efficient profile, but Ekofisk Field is not.

The OD had Phillips Petroleum begin Ekofisk water injection in 1987,

With immediate Positive Results !

(after Nadeau & Ehrenberg, 2006)

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Oil Price Spike of 2008 & The Global Recession

584 Billion usd/yr

annual

monthly

US oil import

Costs from

2000-2008 are

about half of

the US dept ~

3 Trillion usd

for that period.

Page 37: Pn gz 2014

Classification: Internal 2011-09-06

The Golden Zone & Building a Stronger

Energy Bridge to a Sustainable Future

Page 38: Pn gz 2014

Implications for Future Oil Giant Discoveries

• Re-examine regional 2D data for shallow targets, c. 1.7 to 2.7 km depth TVD

i.e. the upper part of the Golden Zone in the North Sea & Mid-Norway

• Focus on Oil rich kitchen areas

• Select Geological sites favourable for stratigraphic / subtle trap geometries

• Integrate with 3D where available

• Include HC indicators such as:

• Oil/Gas Seepage

• Seabed features, pochmarks and cold water coral colonies

• Potential flat spots & amplitude anomalies for fluid contacts

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Historical Examples: 2001 UK Buzzard Oil Field

• Discovered in Viking Graben Rift Flank, June 2001 by PanCanadian

• Reservoir top depth 2.4 km, Temperature c. 90 oC.

• Stratigraphic trap in basin embayment setting

• Small Oil Giant, Recoverable Oil > 0.5 Billion Barrels

• Excellent Quality Upper Jurassic Turbidite sands up to 100 m thick

• Low Gas:Oil Ratio, 33 API gravity Oil, 1.4%S

• Investment: c. 2.4 Billion USD, Production Plateau 200,000 Barrels per Day

• Development costs: c. $5/barrel

•Finding costs: < $1/barrel

Page 40: Pn gz 2014

Buzzard: Largest UK Oil Discovery in c. 25 years

40

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Temp. c. 80oC

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A Large Oil Giant !

Page 43: Pn gz 2014

Where is the Remaining Giant Oil Potential ???

43

Utsira

Buzzard

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Statoil LUT GEO RESBES/phn/01.00

World's Super Giant Oil Fields (> 5 BBO)

Estimated Ultimate Recoverable Reserves BBO

NB: 36 Fields with c. 45% of World's Oil

Most discovered BEFORE 1970

Most are in the Middle East. Ghawar reserves have grown to c 120 BBO since

this graph was made (1992).

Safania

Manifa

Nu

mb

er

of

Fie

lds

Where are the Remaining Oil Super Giants ?

Ghawar Burgan Bolivar

Sarir

E. Texas*

Prudoe Bay

Shengli

Cantarell

Zakum

Kirkuk

Marun

Samotlor

Romashkinskoye

Bermudez

Daqing

Minas

Kashagan: 2000

Tupi ? Brazil

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Global Energy: WHAT WE MUST DO !

• Improve Energy Efficiency: Prolong OUR RESOURCES

• Utilize Renewable Energy: To Improve Efficiency

• Increase Oil & Gas Recovery: Reservoir Geology & Technology

• Selectively & Innovatively Explore for Giant Oil Fields

. . . in the Golden Zone !

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Future Energy: It’s Up to US !

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Value of Golden Zone Oil: Most Efficient Energy

0

2

4

6

8

10

GZ Oil Heavy Oil Tar Oil Oil shale? Bio-Oil

En

erg

y U

nit

s

“It Takes Energy to get Energy ! “

+ ‘Golden Zone’ Oil has the

Highest Net Energy Value

- Other sources are not viable

alternatives . . . IF

they have little or Negative

Net Energy Values, i.e. they

take As Much or More Energy

then they Create.

Oil Sands

NON-VIABLE ?

Highest ‘Net Energy’

?

Page 48: Pn gz 2014

Shale Gas & Oil: The Energy Game Changer

48

Devonian

Mississppian

Devonian

Devonian

Cretaceous

Jurassic

Mississppian

Cretaceous

Cretaceous

Cretaceous

Mississppian

Mississppian

Pennsylvanian

Mississppian

Cretaceous

Source: http://en.wikipedia.org/wiki/Shale_gas_in_the_United_States

Bakken

Page 49: Pn gz 2014

North American Shale Gas and Oil Plays

Geological Age (Bold = Major Plays) Number of Plays (Total = 57)

Miocene 2 (Monterey, Santa Maria Basin)

Eocene 1 (Green River, Uinta Basin)

Cretaceous 10 (Niobrara, Mancos, Lewis, Mowry)

Jurassic 5 (Haynesville)

Triassic 1 (Western Canada Basin)

Pennsylvanian 5 (Excello)

Mississippian 8 (Barnett, Bakken)

Devonian 18 (Marcellus, Antrim, New Albany)

Silurian 1 (Eastern Kentucky)

Ordovician 2 (Utica, Appalachian Foreland Basin)

Cambrian 1 (Alabama, Black Warrior Basin)

49

Source: http://www.marcellus-shale.us/gas-shale_plays.htm

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How to risk uplift and erosion ?

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Classification: Internal

2011-09-06

51

Uplift & Erosion: The Golden Zone Story

North Sea Barents Sea Svalbard

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Impact on Oil & Gas

Exploration Potential • Arresting source rock maturation and

petroleum charge

• Reduction of reservoir pressure

• Gas expansion and oil spilling from traps

• Hydrocarbon phase changes

• Reduction of seal integrity

• Diffusional leakage of reservoired

hydrocarbons over geological time.

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Uplifted Arctic Basin: West Barents Sea

NCS - Barents Sea Reserves

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 500 1000 1500 2000 2500

Oil+Gas+Cond. MMboe

Base R

eserv

oir

Dep

th m

(b

elo

w s

ea b

ed

)

NCS - Barents Sea Exploration Wells

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 10 20 30 40 50 60

Cumulative Number of Wells

Well T

D m

(b

elo

w s

ea b

ed

)

Snøhvit

GoliatUplifted Golden Zone ?

50% Well drilled >

depth then 90%

Of Reserves

NCS - Barents Sea Reserves

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 500 1000 1500 2000 2500

Oil+Gas+Cond. MMboe

Base R

eserv

oir

Dep

th m

(b

elo

w s

ea b

ed

)

NCS - Barents Sea Exploration Wells

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 10 20 30 40 50 60

Cumulative Number of Wells

Well T

D m

(b

elo

w s

ea b

ed

)

Snøhvit

GoliatUplifted Golden Zone ?

50% Well drilled >

depth then 90%

Of Reserves

The NCS Barents Sea

has been Uplifted &

Eroded by circa 1.2 km.

The base of the uplifted

‘Golden Zone’ is now

at circa 2.5 km depth.

Exploration well depths

(50%) have focused

below 2.5 km .

*Although the above suggests that the top of the ‘Golden Zone’ could be at circa 500 m, prospectivity is controlled by

the position of the unconformity erosional surface, and the sealing properties of the geology/lithology below it.

*

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CO2 and Temperature: The Antarctic Record

NB: + Cycle are slightly > than 100,000 years

+ GLACIAL periods are LONG duration

+ INTERGLACIAL period are SHORT duration <= 10,000 years

+ Cycles are asymmetric

+ Emergence to interglacial periods are RAPID

+ Descent to glacial periods are SLOWER

Questions : + Did the arctic ice cap melt in past interglacials ?

+ How much CO2 is required to postpone

descent into the next glacial period ?

Data Source: National Geographic, Sept. 2004, p. 64-65.

INTERGLACIAL

GLACIAL GLACIAL

Fossil Fuels