Nova Scotia / Morocco Conjugate Margins

Nova Scotia / Morocco
Conjugate Margins
Rift history and implications on source rock
deposition
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Nova Scotia
Morocco
Bathymetry of the Central Atlantic ocean
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Moroccan and conjugate
margin play types
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Challenges to exploration
………………………..its the Geology
 Inability to predict reservoir
 Lack of a world class source rock and an understanding
of the ‘petroleum system’
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Themes
Understanding rift history key to developing
models for synrift/early post rift source rock
deposition
 Volcanic/non volcanic margin
 Characteristics and subsidence
 Introduction to Nova Scotia
 Rift history and issues
 Conclusions
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VOLCANIC PASSIVE MARGINS AND
HYDROCARBONS
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VOLCANIC PASSIVE MARGINS AND SALT
BASINS
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VOLCANIC VS NON-VOLCANIC PASSIVE MARGINS;
Thermal subsidence
Volcanic
Non
volc
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Central Atlantic between FZ Pico-Gloria and 15°20’-Guinea. In red, ECMA and WACMA
(Labails, 2007, thesis). In green, Mezozoic magnetic anomalies.
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Paras Ltd, part of the RPS Group
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Middle Triassic reconstruction (≈230 Ma) before rifting (Lebails, 2007, thesis).
Continental crust stretching hypothesis.
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S1
Fit of ECMA and WACMA segments at 195 Ma, (Labails, 2007, thesis).
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Reconstruction at BSMA
(165 Ma, Bathonian/Callovian limit)
(Labails, 2007, thesis).
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Early Jurassic Plate reconstruction (Scotchman 2001)
Toarcian source rock analogue data
Portree Fm (Hebrides basin) Max
thickness = 61.6m (Upper Glen-1);
avTOC=4.6%; avHI=429 (80%
marine kerogen)
Ref. Scotchman 2001
Portree Fm (Slyne Trough) Well 27/13-1
(thickness = 82m) avTOC=4.43%; avHI=463;
avVR=0.5%Ro (90% marine kerogen 10%
TypeIII)
North Yorkshire
Jet Rock
Ultra-rich OIL prone
West Netherlands
Posidoniaschiefer & Aalberg
Fm
Rich OIL prone
Goban Spur basin( Well 62/7-1 (thickness
~600m) avTOC=1%
Mainly inertinite /woody kerogen
GAS prone
Grand Banks
(2 wells with acceptable
RockEval data Eider-M75 &
Murre-G67) (Av. thickness ~50m)
TOCav=1.49%
avS2=3.69; avHI=240
North Celtic Sea (Early, Midle & late Toarcian
intersected in 11 wells) (Av. Thickness=187m)
avTOC=2.5%; avHI=330
Derived from Murphy et al. 1995
Mixed (OIL prone in basin and Gas prone
margins)
South Celtic Sea (Well
49/29-1 (thickness 105m)
avTOC=3.6%; avHI=331
OIL prone
DSDP547 Mazagan
Plateau
No biostrat evidence
for Toarcian
Lusitanian basin (Peniche outcrop) (Toarcian 20m section –
intersection.
10 samples with acceptable RockEval data; 2 samples
However, rich
excluded due to hige S1 and Tmax values)
Sinemurian(avTOC=0.96%; avHI=82)
Pliensbachian SRs
Derived from Oliveira et al. 2006
with definitive
Outcrop evidence of terrigenous plant material in Toarcian
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biostrat
(forams)
(Gas prone)
Oliveira et al. 2006
Paris basin
Lower Toarcian richer(65m);
30m interval in Upper
Toarcian also rich
Marine Type II
avHI>200 up to >700HI
OIL prone
Espitalie et al.1987
Hils Half Graben, Lower Saxony Basin, NW
Germany Lower Toarcian
Posidonia shale
80 samples (VR<0.88%Ro) from 8 wells
(excludes 18 mature samples with
av.VR=1.44%)
Av.TOC=8.7% and avHI=554
TypeII marine kerogens
Radke et al. 2001
Segmentation in the Central Atlantic on the fit
at 195 Ma (Labails, 2007, thesis).
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Evaporites and volcanic
passive margins
 Precursor sag and rift phase- continental – marginal
marine
• Probably low stretching
• Evaporites deposited in post rift phase just prior to and
or contemporaneous with SDR formation
• SDR outer high may have been an effective barrier
enhancing salt deposition?
• Restricted basin post salt favours source bed deposition
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