JUBALAND: The Africa's future Saudi Arebia

[bashe19]

Regional Geology
Offshore Somalia, overlain by the current seismic grid, can
be divided into three basins, each defined by their own
individual structural regimes: Obbia Basin in the north, the
central Coriole Basin, and the southerly Juba-Lamu Basin.
Obbia Basin: The post Early Cretaceous stratigraphy in
this basin is primarily calcareous mudstone 1.5 to 3 km
thick, which overlies very large Jurassic tilted fault block
structures. In places these are crowned by carbonate buildups,
which may be comparable to the Sunbird discovery
offshore Kenya. In the south, large antiformal Cretaceous
to Early Cenozoic structures, interpreted as transpressional
in origin, post-date dramatic Early Cretaceous gravitational
slump structures, indicating that regional tectonics are
significantly deforming the Cretaceous sequences. Karoo
and Jurassic source rocks are a very likely source of oil for
these potentially very large traps.
Coriole Basin: This basin is characterised by very large
scale transpressional and transtensional flower structures,
forming large anticlines related to the north-south strikeslip
motion of transfer faults along the Davie Fracture Zone
and southward movement and rotation of Madagascar.
The Tertiary is represented by a thick siliciclastic section
resulting from historic avulsion of the Shabeelle/Jubba/
Tana river deltas. Using a moderate geothermal gradient it
is reasonable to assume that structural and stratigraphic
traps at Cretaceous and Tertiary levels are likely to have
access to oil-rich hydrocarbons generated from Jurassic and
Cretaceous source rocks.
Juba-Lamu Basin:The Juba-Lamu Basin has the thickest
post-rift stratigraphy of the three basins, up to 12 km.
HANNAH KEARNS, JAKE BERRYMAN, NEIL HODGSON and KARYNA RODRIGUEZ, Spectrum
Peace is bringing hope, seismic exploration and evidence of exciting hydrocarbon-bearing
structures offshore Somalia.
developing a new degree of civil society determined to
bring peace, progress and foreign direct investment to
the region.
Recent positive efforts by the government to boost
hydrocarbon exploration activity have been made
through allowing seismic companies to acquire new 2D
seismic data. An offshore 2D acquisition programme for
Soma Oil and Gas commenced in February 2014, and
concluded in June 2014 with over 20,500 km of seismic
data acquired across a 122,000 km² area, completed
with no security or HSE incidents. Spectrum is to
acquire a second offshore long offset 2D multi-client
survey to complement and infill the existing Soma
grid. The aim is to image to 15 seconds TWT to build
up of a complete understanding of the rifted margin,
as the record length of the existing Soma data is more
limited and only captures the top of the syn-rift section
in the deep offshore area (see foldout on previous
page). Spectrum’s analysis of the existing and new
seismic datasets, integrated with regional
gravity, potential field and satellite seep
data, provides the basis for the following
overview of the tectonostratigraphic history
of offshore Somalia, highlighting potential
play concepts and prospects.
Tectono-stratigraphic Evolution
The initial ‘Karoo’ rifting of the Gondwana
super-continent began in the Late
Carboniferous, and syn-tectonic deposition
of the ‘Karoo Supergroup’ continued until
the Early Jurassic. This Karoo event signalled
the fragmentation of Gondwana, firstly
through the separation of East Antarctica
from East India, synchronous with the
development of an oblique rift valley
between Somalia and the MadagascarSeychelles-India
(MSI) block. The Karoo is
synonymous with the deposition of a worldclass
source rock observed from Yemen to
South Africa. Using existing well data, a
moderate geothermal gradient is inferred
for offshore Somalia, implying that some of
the more deeply buried Karoo source rock is
likely to be in the oil window.
The Jurassic commenced with the
deposition of the Adigrat Formation, when
further rifting and subsequent seafloor
spreading between East Africa and the MSI
block resulted in the separation of Somalia
The deepwater post-rift stratigraphy is characterised by
siliciclastic deltaic sediments, sourced by the Shabeelle/
Jubba/Tana river deltas. The Cenozoic section in the west
is characterised by very large gravity slides on multiple
décollement surfaces, which may be coincident with
early mature organic-rich mudstones. These are the same
mudstones that were reported by Pan Continental and
partners as the main source for the oil in the Sunbird
discovery. Additionally, these slides have created large,
stacked toe-thrust structures downdip, analogous to the
areas of significant success in the Rovuma Basin, offshore
Mozambique (see foldout on previous page).
Beneath the décollement surfaces, thick Cretaceous
clastic-rich sequences of apparent basin floor turbidite
fans are draped over tilted fault blocks and stacked postrift
mass-transport system deposits. The similarity of this
section to the outer regions of the Rovuma Basin east of the
toe thrusts is striking. The main difference appears to be the
lack of a Karimbas Graben equivalent down dip.
The potential for oil in this section will be critical
to exploration interest. A significant observation from
Spectrum’s preliminary satellite seep studies is the
identification of an active oil seep located directly over the
toe-thrust structures where some of these features come
close to seabed. The correlation of active seeps to subsurface
geology is considered key to risk reduction and therefore
these studies are continuing as new data are acquired.
Gigantic Structures
New seismic data from offshore Somalia are revealing
extraordinary structures, in an oil-prone frontier province
that has never been seen or explored before. The data
correlate closely with the potential field results, and the most
recent seismic is imaging gigantic structures that have never
been mapped before.
Striking resemblance to the astonishingly successful plays
in Kenya, Tanzania and Mozambique indicate that offshore
Somalia is about to become the hottest area offshore East
Africa, with not only the promise of huge hydrocarbon
potential, but also a strong indication that this time the hunt
i

[Strategic]

that is cool.the only thing i know for sure is southern offshore has trillions of trillions of ccc of gas like they discovered in mozam and tanzania..

[Strategic]

Mozambique and Tanzania continue to vie for the title of principal exporter of LNG from East Africa. Continuing offshore gas discoveries indicate a huge reserves base (this also bodes well for Somalia's nascent offshore development plans, although Somalia is having problems of its own with establishing a settled federal state system), but regulatory and commercial progress continues to be slow and the present global glut of LNG offers a reduced incentive to race to the market.