Download - International Pavilion

Prepared by
Seychelles National Oil Company Ltd
for
International Showcase
SEG 2002
Patrick R Joseph
Ag. Managing Director
Patrick J Samson
Senior Geologist
• Introduction to Seychelles
• Exploration History
• Technical Issues
• Tectonic Evolution
• Source Rocks
• Reservoirs
• Seals
• Play Types
• Timing
• Indication of HC
• Data Availability
• Economic Issues
- Comprises 115 islands totaling 455 sq km scattered within an EEZ of 1.3 million sq km .
The islands emerging from the main
shallow water Seychelles Plateau,
lying at the northwestern end of the
Mascarene Ridge, are rugged,
verdant granitic peaks that testify to
their continental origin as part of the
onetime supercontinent of Gondwana
Lying between 1 and 12 south latitude within the
western Indian Ocean, Madagascar and the East
African states of Tanzania, Kenya and Somalia are
its nearest neighbours.
Population : 85,000 –Mixed Race living in harmony.
Economy : based mainly on tourism & fisheries
Climate : warm all year round (24 – 30 degree celcius)
Infrastructure
• Versatile main port, being able to handle modern
container ships
• Telecommunications (phone, fax, email) are satellite
linked with direct dialing to most countries
• International airport visited regularly by international
flights from Europe, South and East Africa, the Middle
East and Southeast Asia
Health
Seychelles has a healthy environment, being free of
malaria, yellow fever and other contagious diseases,
and no vaccination certificates are required except
from affected areas as recommended by W.H.O
The turn of the seventies witnessed the first reflection in the Seychelles region
1973: Burma Oil acquired 470km of reconnaissance seismic
1977-1979: Oxoco,Siebens and a Burma Oil-led consortium acquired
some 6,400km of seismic data
1980/1981: Amoco drilled 3 wells on the western shelf
1982: Amoco commissioned a 27,900km aeromagnetic survey
1983: Amoco: Amoco acquired 7,100km of seismic, gravity/magnetics and
Waterborne gas sniffer data.
1986: SNOC was formed
1987: Enterprise acquired 4,870 km seismic,
And gravity/magnetic data.
1991: Texaco/Ultramar/Enterprise acquired
3,675km of seismic and gravity/magnetics
1991: Enterprise conducted an airborne UV
Fluorescence seepfinder survey.
1995: Enterprise oil drilled the constant Bank Well.
Canmar Explorer III during the
Drilling of constant Bank-1
Tectonic Evolution
The complexity of the tectonic evolution of the Seychelles Plateau is due to the imposition of
three phases of rift/drift tectonics that eventually cleaved the microcontinent from the centre
of Gondwana.
Early Cretaceous (~150 Ma0.
After separation of East and
West Gondwana
Early Late Cretaceous (~95 Ma).
During Seychelles/India split from
Madagascar.
Paleocene (~60 Ma). During
The separation of India from
Seychelles.
Source rocks
Composite Stratigraphic Column
showing source rock horizons
H/C vs O/C Diagram for the
Middle Jurassic to Lower
Cretaceous source rock
Hydrogen Index vs Oxygen Index
for the lower to early middle
Jurassic source rock.
Note: Oil-prone Type II kerogen occurs in liptinitic coals (TCO = 63.4%)
within early Middle Jurassic deltaic shales.
Beach standings of tar are a regular occurrence in
Seychelles.
The tars collected are correlable to the local
stratigraphy.
Reservoirs & Seals
Where penetrated on the Western Shelf, fluvial and deltaic
sandstones of rift origin had measured porosities up to 22% with
flow rates of up to 1200 BWPD indicative of reasonable
permeabilities. Early drift carbonates had porosities up to 18%.
Similar or better porosities are expected in the younger rift clastics.
Seals are present both regionally, as marine shales of drift origin, and locally,
as shale interbeds within fluvial and deltaic sequences
Play Types
Tilted Fault Blocks
Clastic continental and mixed clastic/carbonate marginal marine
sequences of Triassic to Middle Jurassic and Late Cretaceous rift origin
provide reservoirs and source rocks. These, and the capping and sealing
fine-grained marine clastics, that also have source potential, have been
block faulted during subsequent rift tectonism.
Play Types
Stratigraphic Pinchout
Regressive marginal marine clastic sequences developed within a Late
Cretaceous pull-apart rift basin provide reservoirs and source rocks. The
landward pinchout is sealed between the underlying granitic basement and
over-stepping fine grained clastics of transgressive marine origin.
Play Types
Reefs
Barrier and fringing reefs developed on passive margins
during Late Cretaceous and Tertiary drifting. Earlier marine
shales, and associated marine shales and micritic carbonates
could, respectively, source and seal the vuggy carbonate
reservoirs
Play Types
Carbonate Onlap/Compactional Drape
Tertiary shelf carbonate onlap upon, or compactional drape over,
major basement horst blocks or possible local volcanic edifices.
Vuggy carbonate reservoirs are possibly sourced and sealed,
respectively, by earlier or associated marine shales or micritic
carbonates
Play Types
Wrench Fault Anticlines
Wrench fault tectonics of latest Cretaceous/early Tertiary age
created potentially large anticlines within Late Cretaceous
progradational marine clastic sequences, containing reservoir
facies. Overlying fine grained calcareous ooze could act as
seals
Maturation v/s Timing
• Recent AFTA and basin modeling has revealed a complete heating history.
• The principal heating event that took source rocks to organic maturity was the Deccan
volcanic event at the Cretaceous/Teriary boundary, but other significant heating events both
pre-, and post-date this event.
•The majority of structures had thus formed prior to the generation and migration of
hydrocarbons
HC Indicators
Although none of the exploration wells discovered accumulations of hydrocarbons, shows in
each well on the Western Shelf, plus other hydrocarbon indicators, indicate that
hydrocarbons have been, and/or still are being generated from mature source rocks.
• 23,150 line km of seismic
- gravity & magnetic
• 27,911 km aeromagnetic
• Well data from the 4 wells drilled
• Gas sniffer survey (7,101 km)
• UV Fluorescence seep survey
• Several reports relating to the geological
History and petroleum potential of Seychelles
Seismic coverage Map
The Model Petroleum Agreement was designed specifically to create a favourable
environment for investment in petroleum exploration by oil companies.
Contract type: Modern Concession-type with no State participation.
Rent: US$10 per sq. km per year and adjusted annually for inflation.
Royalty: 5% on gross production, but the Minister can reduce the rate for marginal fields.
Bonuses: No signature or discovery bonuses.
Training: A fund for training Nationals to be established by negotiation.
Valuation: International fair market valuation of crude oil.
Petroleum Income Tax: 35% with:
* immediate expensing of all exploration and development costs for tax purposes;
* unlimited carry forward of losses; and
* no field ring-fencing.
Additional Profits Tax:
* Computed on cash flows denominated in US dollars;
* levied on field-by-field basis;
* two tier APT triggered only after the investor has earned a reasonable return on all expenditure;
* trigger points and rates agreed upon by negotiation
.
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