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Satellite Seep Detection of

Leaking Deep Water Oilfields,

Fact or Fantasy?

Alan Williams, Fugro NPA, UK, May 26, 2010

- A review of 15 years of accumulated wisdom

from present-day deep water hot spots, such as

the Gulf of Mexico, Angola and the Black Sea to

the emerging frontiers of Greenland and New

Zealand

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Acknowledgements

I would like to acknowledge

the contributions to this presentation by my

colleagues, Mike King of FNPA and Dr Geoff

Lawrence of TREICoL

Dave Bamford and Finding Petroleum for

accepting my somewhat verbose title

Lord John of Maddingley for releasing me

from the bondage of working as a cosseted oil

company employee and for giving me nearly

20 years to appreciate life as a humble

contractor.

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NPA HQ, Crockham

Park, Kent

Chartwell House, Winston

Churchill’s former home

Hever Castle, Anne Boleyn’s

former home

Where are

NPA?

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What do we do?

Oil Field

SubsidenceGeological

InterpretationImagery

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The title is already a fantasy. SAR can’t detect oilfields directly, but it can

map slicks and some slicks are natural oil seeps and most natural oil

seeps come from leaking traps. What SAR does best is to reduce

source risk, at basin and playfairway scale

So a more correct title would be

„Satellite Slick Detection, some of whom may have

originated as seeps from leaking oilfields. Fact.

Mission Statement Correction

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Six key questions

What does SAR Detect and how does it do it?

What is a seep and why are they useful?

How do you prove a slick is a seep?

What array of tools do you need to validate a SAR ‘seep’?

How successful is SAR seep mapping? How many oil discoveries have

followed? Where are they?

What’s the future for SAR slick mapping?

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What is a seep?

A seep is: “The surface expression of a migration pathway along which petroleum is

currently flowing driven by buoyancy from a sub-surface origin” (Clarke &

Cleverly, 1991)

Premise; all clastic seals will leak; only layered salt or anhydrite

are perfect seals

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Are seeps useful? Yes, throughout history

2000 BC; bitumen sealed

bathing pool, Indus Valley

14C; Persian naptha-

fuelled mechanical

horses

16C; Sir Walter Raleigh- Trinidad asphalt

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Oil seeps were the precursor of many of the major oil discoveries of the

20th century.

1885, Sumatra

1901, Spindletop, Texas

1905, Oklahoma

1908, Persia- Majid-i-

Sulaiman,

1910, Mexico - Golden Lane

1922, Venezuela - Los Borroso

1927, Iraq - Kirkuk

1930, East Texas

1932, Bahrain

1938, Kuwait - Burgan

Onshore seeps and Oilfields well known

The geologist seems a lot happier than the

drillers!

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Cautionary tale 1; Onshore seep detection is tricky

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How does SAR work and what is it detecting?

• Satellite SARs are single wavelength, side-looking radars that have polar

orbits and a return visit time of c.1 month so images the ocean multiple

times. This allows us to locate repeat slicks – the key information

• They detects areas of wave-suppressed ocean surface sometimes

caused by oil slicks = Fresnel Scattering = black. Waves cause Bragg

scattering = grey. What could be simpler?

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Not quite as simple as it looks, wave damping has

many possible origins There are 3 principal types of slicks that SAR detects

– Pollution Slicks – mostly illegal ship dumping; by far the largest category

– Natural Oil Seeps – our target group

– Natural Film slicks – formed by organic material (plankton, algal blooms,

etc) which only form at very low wind speeds

– We map the first two, observe but do not map the third

Pollution Slick Seepage Slicks Natural Film Slicks

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Goechem required to prove a slick is a seep – validation

Qu. How do we validate that SAR slicks are seeps?

A. FNPA’s 6 Step Validation Programme

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Step 1 : airborne slick spotting and/or co-ordinated

with slick sampling vessel

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Step 2: Map the sea-bed – multibeam and/or sub bottom

profiling

Can images seep

related features, such

as carbonate mounds

- and gas bubble

plumes

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Step 3: Slick sampling and sea bed coring

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Step 4: deploy ROV (or manned submersible) & obtain

seep vent samples

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Step 5: Sample seep vent, run geochem and

correlate to slick & reservoired oil

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Step 6: correlate to seismic

Fugro Multi Client Services

Seepage

area

Rank 3

Seepage along

fault?

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Fugro have all the kit you need

Satellite seeps investigation: Fugro NPA Ltd.

Shallow seismic interpretation: Fugro Robertson Ltd.

Positioning and multibeam:

Fugro Offshore Survey

Core acquisition:

Geochem Analysis :

Fugro Geolab Nor

Surface Geochemistry

Acquisition

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So what are the criteria for leaky basins?

Primary controls

High sedimentation rates (overpressure)

Salt structures - faults over diapirs

- salt-sediment interface

Active faulting and/or seismicity

Tilted aquifers

Secondary controls

High GOR oils

High API oils

High formation water salinity

(after Clayton et al, 1991)

www.fugro.comAfter D.MacGregor, 1993

Seepage and basin type; leaky vs. non leaky

High leakage types

• Compressive associations – e.g. fold and thrust belts (onshore);

strike slip margins (offshore) – Venezuela, Peru

• Diapiric associations with piercements to surface e.g. back-arc

basins with later compression - South Caspian, Black Sea

• Diapiric associations with faults over diapirs; including passive

margins with late stage diapirism- GoM, Mexico (Campeche),

Angola, Nigeria (Red Sea)

Medium leakage types

• Extensional associations, e.g. rift basins, especially those with

recent generation & migration- Red Sea, Rift Lakes

• Passive margins with thick unfaulted post rift sections

Low leakage types

• Foreland basins

• Intra-cratonic basins (not relevant to offshore).

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Spectrum of Basin Leakage Styles (BP field

examples (Thrasher et al.1996)

Santa Barbara GoM Cartagena

North Sea (CNS) Haltenbanken N. Viking Graben

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Seepage & Reserves

0

50

100

150

200

250

300

0 2 4 6 8 10 12

Reserves BBOE

No

of

Seep

s

Heavily

deformed

basins

Lightly

deformed

basins

(from Macgregor, D. 1993)+

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Detecting Offshore Seepage is easier

Surfacing oil seep from

survey boat

Gas bubble with oil film bursts

at surface creating an oil

‘pancake’

Photo from Aircraft at 80m

Seepage Slick from a light aircraft

Sustained seepage will result in

‘pancakes’ coalescing to form a slick.

These features can be observed from

space

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26

Identifying repeating emission points is the key differentiator

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Essential requirements 1, 2 & 3

1. A flight

crew 2. A porthole plus

Ray-bans 3. An able assistant

plus Petronas client

Cautionary tale 2. Not all point sourced slicks are seeps- 1990

East Malaysia Da Gama survey example

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Impressive results: many slicks, some very large,

in excess of 5km with an active emission point, seepage

or not?

Emission

point?

Labuan Island mega slick – have we

struck gold or is this a leaking pipeline?

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Same slick, four hours later - c.10km x 5km

Emission

point?

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30

Mega-slick located 5km SW of Labuan Island;

not burst pipeline, so seepage (breached seal) or not?

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A quake! - moral of

the story, go seep

hunting after

earthquakes?

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Fugro NPA - Current GOSD

• 11,000 interpreted SAR scenes

• 100,000 slicks interpreted.

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Slick Categorisation Parameters

Location

– e.g. Shipping Lanes offshore

production/pipelines

Size

– (Length Aspect Ratio)

Morphology

– (Curvature, corkscrew, dog

leg)

– Slick edge sharp or diffuse

Direction of Flow

– (Wind, current, tide)

Context

– Repetition

– Distribution pattern

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Onshore seepage Database

FNPA now able to sell offshore seeps and Fugro Data Solutions onshore seeps

and GIR database.

This creates the only global on and offshore seepage database in existence.

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Global repeats

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Where are the SAR Hot Spots? What basin

types?

Strike Slip – Venezuela, Peru

Diapiric – Gom, Mexico, Nigeria, Angola, Caspian, Black Sea

Rift – Red Sea, Rift Lakes

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Americas Deep Water Hot Spots –

US & Mexico GoM

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Gulf of Mexico deepwater

Dense repeating seepage

coincides with many fields.

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Prolific oil seepage

over a vast region and

in waters to 3000m+

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Salt is the major control on seepage

Salt pod

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Main migration pathway :

salt diapirs

Bahía de Campeche - salt diapirs

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Seepage repeats continuously in every

image acquired over 6 years; some x5, in

3200m water depth

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Slicks mapped by SAR

3000m vertically above

seafloor vents

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Huge asphalt

‘lava’ flows, plus

chemosynthetic

communities at

sea-bed

Deep Water Campeche- amazing asphalt ‘dykes’ below

repeat SAR seeps (MacDonald 2003)

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Eurasia Deep water Hot spots –

Black Sea, Caspian Sea.

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Eastern Black Sea

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Repeats from

1999 to 2005+

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African Deep Water Hot Spots

- Nigeria, Angola, Uganda

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Angola Example - Congo Fan

Blocks 31-34 SAR screened in 1998/99 before 1st d/w licensing round

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African Rift lakes – example seep

Cape Kalumba Seep, Lake Tanganyika

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566 weather compliant and interpreted scenes (red)

150 new scenes (purple) to be purchased for a circum

Greenland cover

Grenland; emerging new deep water frontier 1

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2009 Blocks, complete coverage

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Scott Trough Seeps

Aerial view of oil

seepage Scott Trough,

NE coast Baffin Island,

August 1990

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West Coast Results Extract

No

pollution

Strong

Cluster

No shortage

of slicks but

generally

low rank

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Quicklook Hyperlink

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– additional controls on seepage

Mixing of warm Gulf Stream & Arctic water results in high biological productivity

Algal blooms and therefore dense natural film

– Both confuse interpretation

Strong down-welling of fresh melt-water can suppress seepage

Seasonal melt/warming results in strong layering of water column - this can displace & suppress seepage reaching the surface

Dispersing pack ice and grease ice can confuse interpretation

- Greenland

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Emerging deep water frontier 2- New Zealand

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Raukamura - mini case history(from FNPA and GNS Consultancy Report 2008/111)

Repeat Slicks

(100+) and GIR

seeps

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Raukamura – structural setting

• Forearc setting –

new basin (1980)

• Tectonically active

• 11,000 ft of K & T

• OEW – 4-6km

• 2-3000m WD

• Onshore seeps

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Rakamura, Seep Geochem (GNS data)

Primary Source is marine Late Paleocene Waipawa Fm.

Also LK Whangai Fm.

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Raukamura, Seismic Grid

SAR Slick (approx)

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Raukamura – potential trapping structures (line

Rau 07-03, GNS) correspond to SAR slicks

SAR slicks, approx location

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DHIs on line Rau 07-03, corresponding to SAR slicks

SAR slicks (app) SAR slicks (app)

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Does SAR work? – Fact or Fantasy? The Story so far

Hot Spot SAR

Repeats

SAR Seeps

Validated

Discoveries Fact Or

Fantasy?

GoM Yes Yes

(BP, GERG)

Many, post SAR Fact

Mexico/Cariaco Yes Yes Not yet Fact

Peru.Trjuillo Yes Yes

(PetroPeru)

No (?R) Fact

Angola Yes Yes (TDI) Yes, post SAR Fact

Nigeria Yes Yes (TDI) Yes, post SAR Fact

S. Caspian Yes Yes (BP &

Lasmo)

Not many (?C)

(post SAR)

Fact

East Black Sea Yes Yes (Rize) No (?R) Fact

Red Sea Yes No Not yet Fact

Rift Lakes Yes Yes Yes (Lake

Albert)

Fact

Arafura No No Not yet Fact

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Conclusions

SAR is particularly effective in deep water leaky basins with a black oil charge, especially if slicks can be

sampled for geochemistry. Reduces (eliminates?) charge risk

SAR data from medium and low leaky basins are also of value, especially when combined with other

collateral seep-related data (gas chimneys, pock marks, DHIs, multi-beam data, etc) , eg.Raukamura

Prolific seepage in itself is not a guarantee of success, e.g. South Caspian, Trujillo Basin as reservoir,

seal or timing may be reasons for well failure.

SAR screening data from deep water Angola and deep water GoM predicted major oil discoveries

The Fugro Seeps Database (GOSD) has highlighted several untested Frontier basins where oil charge

and trap leakage is occurring – e.g. deep water Campeche, the Cariaco Basin and the Eastern Red Sea

SAR Slick detection is an effective exploration screening tool, whose value is increased when followed

up by a programme of surface geochemistry and sea-bed mapping and then integrated with seismic

data. e.g, Raukamura, New Zealand

A new generation of high resolution (1m to 5m resolution) SAR platforms – Cosmo Skymed, TerraSAR

X and Radarsat 2, will now allow be able to resolve much smaller, higher API oils and condensate and

possibly gas seeps

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Thank You