offshore east africa-where is all the oil? · 2 introduction sudan south sudan democratic republic...

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Offshore East Africa-where is all the oil?

Jeremy Berry

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Introduction

Sudan

South Sudan

Democratic

Republic of

the Congo

Tanzania

Mozambique

Zimbabwe

Zambia

Ethiopia

Kenya

Uganda

▪ Offshore East Africa, only

gas has been found in

commercial volumes

▪ Oil discoveries onshore

Uganda, Kenya,

Mozambique and

Madagascar – along with

numerous seeps along the

coast – encourage the

continued pursuit of the

elusive offshore oil.

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History of Exploration

▪ 1950-1964 Majors perform geological studies and the petroleum system is proven.

▪ 1964-1980 Seismic surveys shot and 5 wells drilled. AGIP discover Songo Songo Gas

field. Gulf Oil discover Pande & Buzi Gas fields.

▪ 1980-1990 Increased drilling period. ENI discover Mnazi Bay gas field.

▪ 1990-2000 Exploration efforts wane due to prediction of gas-prone source rocks.

▪ 2000-2009 First gas produced Songo Songo and Mnazi Bay.

▪ 2009-2014 Renewed exploration with intensive drilling campaigns resulting in

multiple multi-TCF gas discoveries in Mozambique and Tanzania.

Sources: TPDC, INP, Wenworth Resources, Orca Exploration

1950 2014 1964 1980 1990 2000

Pande & Buzi

Discovery

Mnazi Bay

Discovery

Temane

Discovery

Songo Songo

Discovery

1st Rovuma gas

discoveries

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Postulated Source Rocks

Source: TPDC

Paleogene-Neogene:

Restricted to localised pro-delta

environments and rarely attained

sufficient thermal maturation.

Post mid-Jurassic – Cretaceous:

Likely to be gas prone due to paucity

of oil-prone kerogens at the time.

Lower-Middle Jurassic:

Generally deeply buried. Widespread

Miocene inversion thought to have

flashed much of the oils to gas.

Triassic:

Likely to be over-mature.

Permo-Carboniferous:

Compositionally prone to be gas bearing.

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Palaeogeography

Shell, 2003

Early Jurassic

Transition between Permo-

Trias rifting and sea-floor

spreading.

Thermal doming between

Tanzania and Madagascar

Mid-Late Jurassic

Madagascar begins

southerly drift along Davie

Fracture Zone.

Source rocks deposited in

semi-restricted settings.

Cretaceous

Continued drift of Madagascar.

Major deltas begin to form in

coastal basin.

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▪ An Early-Mid Jurassic marine shale is thought to source much of the gas in

offshore Tanzania and Mozambique.

▪ This source rock has not yet been directly sampled.

▪ Is gas being generated because?

– The source rock predominantly lies within the gas window.

– Some areas of this source rock had high gas-prone terrigenous input

Bamford, D. 2012

Natural Gas assets in East Africa Source Intervals

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BLOCK 3BLOCK 3BLOCK 3BLOCK 3BLOCK 3BLOCK 3BLOCK 3BLOCK 3BLOCK 3

MANDAWAMANDAWAMANDAWAMANDAWAMANDAWAMANDAWAMANDAWAMANDAWAMANDAWA



AREA 1AREA 1AREA 1AREA 1AREA 1AREA 1AREA 1AREA 1AREA 1


PWEZA


BLOCK EBLOCK EBLOCK EBLOCK EBLOCK EBLOCK EBLOCK EBLOCK EBLOCK E

BLOCK FBLOCK FBLOCK FBLOCK FBLOCK FBLOCK FBLOCK FBLOCK FBLOCK F

BLOCK 36BLOCK 36BLOCK 36BLOCK 36BLOCK 36BLOCK 36BLOCK 36BLOCK 36BLOCK 361139 11139 11139 11139 11139 11139 11139 11139 11139 1

MNAZI BAY NMNAZI BAY NMNAZI BAY NMNAZI BAY NMNAZI BAY NMNAZI BAY NMNAZI BAY NMNAZI BAY NMNAZI BAY N


1139 31139 31139 31139 31139 31139 31139 31139 31139 3

BLOCK DBLOCK DBLOCK DBLOCK DBLOCK DBLOCK DBLOCK DBLOCK DBLOCK D



BIGWA-RUFIJIBIGWA-RUFIJIBIGWA-RUFIJIBIGWA-RUFIJIBIGWA-RUFIJIBIGWA-RUFIJIBIGWA-RUFIJIBIGWA-RUFIJIBIGWA-RUFIJI

EAST PANDEEAST PANDEEAST PANDEEAST PANDEEAST PANDEEAST PANDEEAST PANDEEAST PANDEEAST PANDE

ROVUMA ONROVUMA ONROVUMA ONROVUMA ONROVUMA ONROVUMA ONROVUMA ONROVUMA ONROVUMA ON

MNAZI BAYMNAZI BAYMNAZI BAYMNAZI BAYMNAZI BAYMNAZI BAYMNAZI BAYMNAZI BAYMNAZI BAY

BLK-3ABLK-3ABLK-3ABLK-3ABLK-3ABLK-3ABLK-3ABLK-3ABLK-3A

KISANGIREKISANGIREKISANGIREKISANGIREKISANGIREKISANGIREKISANGIREKISANGIREKISANGIRE

SELOUSSELOUSSELOUSSELOUSSELOUSSELOUSSELOUSSELOUSSELOUS

RUVURUVURUVURUVURUVURUVURUVURUVURUVU

BLK-4BBLK-4BBLK-4BBLK-4BBLK-4BBLK-4BBLK-4BBLK-4BBLK-4B

BLK-3CBLK-3CBLK-3CBLK-3CBLK-3CBLK-3CBLK-3CBLK-3CBLK-3C


NTORYANTORYANTORYANTORYANTORYANTORYANTORYANTORYANTORYA





BLOCK 5BLOCK 5BLOCK 5BLOCK 5BLOCK 5BLOCK 5BLOCK 5BLOCK 5BLOCK 5 BLK-5BBLK-5BBLK-5BBLK-5BBLK-5BBLK-5BBLK-5BBLK-5BBLK-5B BLK-5CBLK-5CBLK-5CBLK-5CBLK-5CBLK-5CBLK-5CBLK-5CBLK-5C

LINDILINDILINDILINDILINDILINDILINDILINDILINDI

SONGO SONGOSONGO SONGOSONGO SONGOSONGO SONGOSONGO SONGOSONGO SONGOSONGO SONGOSONGO SONGOSONGO SONGO

MAFIAMAFIAMAFIAMAFIAMAFIAMAFIAMAFIAMAFIAMAFIA





ESPADARTE

ORCA

ZIWANI

CORAL

MZIA

JODARI

PAPA

MAMBA COMPLEX

LAVANI

TANGAWIZI

AGULHA

MRONGE

MKIZI

MoroniMoroniMoroniMoroniMoroniMoroniMoroniMoroniMoroni

50.000

kilometres

Gas Discoveries - Mozambique and Tanzania

▪ 20-30 TCF

discovered

offshore

Tanzania

▪ 120-150 TCF

discovered

offshore

Mozambique

Source: PetroView

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Ages of Gas Discoveries in Tanzania

Source: TPDC

Pliocene Carbonate: Ziwani

Oligocene Slope Channel: Chaza (Block 1)

Miocene Slope Channel: Mkizi (Block 1)

Oligocene Delta: Mnazi Bay, Msimbati

Paleocene Slope Channel: Jodari (Block 1),

Lavani & Tangawizi (Block 2), Pweza, Chewa &

Ngisi (Block 4)

Campanian Slope Channel: Mzia (Block 1),

Zafarina (Block 2) and Papa (Block 3)

Neocomian Shoreface sands: Songo Songo

Albian Delta sands: Ntorya

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Other oil play factors - Crustal Type

Class et al. & Danforth et al. 2012.

• The nature of the crust which underlies the East African margin is subject to

current debate.

• Geochemistry of the Grand Comore lavas indicate an oceanic crustal signature

to the Comoros islands - a useful Eastward constraint upon the location of the

crustal boundary.

• Gravity and magnetics data over the area is also subject to debate, as seafloor

topography associated with the Davie fracture zone and Rovuma delta make

the interpretation more difficult.

• Attempts have been made to pick a distinct crustal boundary on 2D seismic

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Offshore Oil Discoveries?

Pancontinental

Kenya - Sunbird-1

▪ The well was completed in the March 2014.

▪ Water depth 723m

▪ ~900m of overlying sediment

▪ “ . . . gross 29m gas column overlying a gross 14m (9.2m net) oil column” in a Miocene Pinnacle Reef.

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Kenya – Lamu Basin

▪ Davie-Walu Ridge

▪ Tembo trough

▪ Simba High

Pancontinental, 2014

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Kenya – Lamu Basin Reef Play

▪ Prognosed Eocene source

▪ East of the Simba High, Cretaceous age clastic play

expected to be sourced by gas mature Jurassic.

Ophir, 2014

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Further Lamu Basin oil leads

Ophir

Miocene build-up oil prone leads

Sunbird-1

Tertiary

Grabens

Miocene

Build-up

Trends

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Offshore oil discoveries?

▪ Ironclad-1 drilled by Anadarko had oil (and gas) shows in

tight Cretaceous deepwater fan sandstones in Area 1

offshore Mozambique. 2010.

Maps: Deloitte Petroview. Cartoon: Adapted from Law, C. 2011.

Ironclad

Mozambique - Ironclad

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Offshore oil discoveries?

▪ Oil presumably sourced from less deeply buried Jurassic underlying the prospect.

▪ Cretaceous reservoir of poor quality, unlike the neighbouring Tertiary gas bearing

sands

Seismic and Cartoon adapted from Law, C. 2011.

Ironclad-1

Mozambique - Ironclad

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Offshore Kenya

Anadarko Kubwa well in the L-07 Block offshore Kenya,

encountered non-commercial oil shows in reservoir-quality

sands.

Anadarko and Ophir

Ophir indicates that

satellite slick studies

suggest an oil-prone

region offshore

Kenya

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Conclusions

Oil in commercial quantities remains elusive offshore East Africa.

The widespread Jurassic source rocks tend to be in the gas window.

Less deeply buried Jurassic sources could perhaps exist: Closer to shore,

In deeper water where there may be less overburden,

In sub-basins with different tectonic history

Alternative (younger) oil mature source rocks may be developed in restricted sub-basins

Any detailed source rock information from recent wells is proprietary.

Recent Tanzania offshore license round had limited appeal (is more gas in deeper water further from the shore attractive?)

But there were successful bidders. What do they think they know?

GCA would be pleased to help you in this ongoing pursuit.

GeoExpro

offshore east africa-where is all the oil? · 2 introduction sudan south sudan democratic republic...

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