Sedimentology and petroleum potential of the late Cretaceous Shiranish Formation in the Euphrates Graben, Syria [Elektronische Ressource] / vorgelegt von Shirin Ismail

Shirin Ismail

Informations

• Publié par: technische_universitat_berlin
• Publié le: 01 janvier 2011
• Nombre de lectures: 18
• Langue: English
• Poids de l'ouvrage: 17 Mo

Extrait

Sedimentology and Petroleum Potential of
the Late Cretaceous Shiranish Formation
in the Euphrates Graben, Syria


Vorgelegt von
Diplom-Geologin
Shirin Ismail
aus Lattakia (Syrien)


Von der Fakultät VI- Planen Bauen Umwelt
der Technischen Universität Berlin
zur Erlangung des akademischen Grades
Doktor der Naturwissenscaften
-Dr. rer. nat-
genehmigte Dissertation



Promotionsausschuss:
Vorsitzender: Prof. Dr. rer. nat. Gerhard Franz
Berichter: Prof. Dr. rer. nat. Brian Horsfield
Berichter: PD. Dr. rer. nat. Hans Martin Schulz

Tag der wissenschaftlichen Aussprache: 17. 01. 2011


Berlin 2011

D83



































ii PhD-Dissertation by Shirin Ismail
CURRICULUM VITAE
Personal information
Name: .................. Shirin Ismail
Gender: ................ Female
Birthday: ............. October 05th, 1978
Birthplace: ............Syria
Nationality: .......... Syrian
Marital status: ...... Single

Education and Work Experience

2006-2010 PhD student in Organic Geochemistry Section - at the German National
Research Central for Geosciences (GeoForschungsZentrum- Potsdam) Germany and TU-
Berlin University- Germany.
2003-2004 Assistant in the Department of Applied Geology at the University of
Aleppo, Syria.
2002-2003 Diploma in Geophysics, oil and gas exploration - University Damascus,
Syria.
1997-2001 Bachelor in Applied Geology - University of Tishreen, Syria.








i PhD-Dissertation by Shirin Ismail






















ii PhD-Dissertation by Shirin Ismail
ABSTRACT

The Shiranish Formation (Campanian-Maastrichtian) was deposited during the pre- to synrift
phase of the Euphrates graben formation, and can reach a thickness of more than 1,000 m.
The calcareous to marly sediments are rich in organic carbon and are potential source rocks in
the Euphrates Graben (Syria).
The subdivision into a lower and an upper part of the Shiranish Formation (USF, LSF) is
overprinted by sedimentary cyclicity on high frequency (alternations of light-coloured and
dark clay-rich intervals). The LSF is characterized by minor-scale variations, whereas the
USF is characterized by intensified changes both reflected by petrophysical properties.
According to the mineralogical composition, the USF is composed of two submembers USF-1
and USF-2. The LSF and USF-2 resemble in higher kaolinite content and ankerite occurrence
13and lower δ C values, which indicate palaeo-methanogenesis. In contrast, USF-1 is charac-org
terised by intense organic matter and carbonate deposition pointing to a highstand situation.
A kerogen type II to II-III, and continuously increasing total organic carbon (TOC) contents
and hydrogen index (HI) values characterizes the USF. In the central graben the USF is
characterized by low diasterane indexes and Ts/(Ts+Tm) ratios, indicating anoxic mix clay-
carbonate source rocks. In contrast, the LSF is characterized by a kerogen type II-III, and
lower TOC contents and HI values. The oxygen index (OI) values are markedly higher than in
the LSF. Moreover, the LSF has relatively high diasterane index values and Ts/(Ts+Tm)
ratios, representing a fine-grained siliciclastic influence.
A high sedimentation rate prevailed during deposition of the USF, and higher amounts of
15marine organic matter were incorporated in the sediments compared to LSF. δ N values
increase from bottom to the top of the Shiranish Formation (from 3 ‰ to 7 ‰) and indicate a
progressively higher palaeo-productivity and water-column dentrification.
The major controls on the heterogeneities of organofacies are variations of the depositional
environment and bottom water oxygenation. A strong input of terrestrial organic matter under
shallow marine conditions prevailed during deposition of LSF sediments. This terrestrial
organic matter input delivered gas-prone material in contrast to the predominance of oil-prone
organic matter in the USF. During sedimentation of the USF extended bottom water anoxia
prevailed.
Maturity varies laterally from immature organic matter in the eastern and northeastern graben
to mature organic matter towards the central and northwestern graben that plot in the oil

iii PhD-Dissertation by Shirin Ismail
window zone and generated good potential petroleum.
The LSF in the central graben shows a good potential for hydrocarbons, and a higher potential
in the USF. Along the graben margins the LSF and USF-2 exhibit a good source rock
potential, whereas USF-1 has very good to excellent source rocks potential. These differences
are due to differences of abundant of organic matter and its types. The USF in the central
graben and the USF-1 in the margin contain abundant organic matter of type II or I and
provide with the sufficient burial depth a very good source rock in the central graben.
Open system pyrolysis reflects that the LSF and USF contain predominately-marine kerogen
with a strong aliphatic hydrocarbon signature and relatively small sulphur contents. They have
the potential to generate paraffinic-naphthenic-aromatic low, high and high paraffinic wax
crude oil. However, the Shiranish Formation in the northern graben contains higher amounts
of oxygen-containing functional groups and has a high proportion of aromatic hydrocarbons
and phenols. This is due to a higher terrigenous organic matter content and results in a
relatively higher gas-proneness.
Bulk kinetic investigations show a broad activation energy of the LSF (48 - 68 kcal/mol) and
a narrow activation energy pattern for the USF (52 - 60 kcal/mol) for hydrocarbon generation
+14in the central graben, while the frequency factors also show differences from 1.5 E to 8.7
+15 -1E min . Moreover, broad activation energy distributions is characterised in the USF and
the LSF in margin graben. These kinetic parameters were used to model the rates of natural
geological heating. The predicted petroleum formation began at 136 °C for the USF and at
144 °C for the LSF. This corresponds to ca. 360 m difference in burial depth for petroleum
formation.
Compositional kinetic modelling based on results of MSSV pyrolysis shows that gas
generation of the LSF requires activation energies of 59 - 63 Kcal/mol compared to the Upper
Shiranish Formation. In contrast, the Upper Shiranish Formation is characterized by a higher
oil potential coupled to lower activation energies (52 - 56 Kcal /mol).
Gas kicks during drilling the LSF can be interpreted by two scenarios. First, the LSF is a self-
sourced interval. Oil was generated and retained in the lower Shiranish Formation and cracked to gas
when buried to greater depth. Second, gas was generated in the underlying R‟mah Formation
and migrated upwards. The last scenario would imply that the shaly intervals within the lower
Shiranish Formation acted as trap for this gas.


iv PhD-Dissertation by Shirin Ismail
ZUSAMMENFASSUNG
Die Shiranish Formation (marine Fazies, Campanium-Maastrichtium) wurde während der
Synriftphase der Euphratgrabenentstehung abgelagert. Sie kann eine Gesamtmächtigkeit von
über 1000 m erlangen. Die kalkig bis mergeligen Sedimente haben einen hohen organischen
Kohlenstoffanteil und sind potentielle Muttergesteine im Euphratgraben (Syrien).
Der untere bzw. der obere Teil der Shiranish Formation (USF, LSF) ist durch hochfrequente
Ablagerungszyklen geprägt (Wechsellagerung von hellen und dunklen, tonreichen Inter-
vallen). Die LSF ist durch kleinräumige Variabilität gekennzeichnet, wohingegen die USF
durch intensive Änderungen gekennzeichnet ist. Beides spiegelt sich in den petrophysi-
kalischen Eigenschaften wieder. Aufgrund der Mineralzusammensetzung, wird die USF in
zwei Subforamtionen, die USF-1 und die USF-2, unterteielt. Die LSF und die USF-2 ähneln
13sich durch ihren hohen Tonanteil, im Auftreten von Ankerit und in niedrige δ C Werten, org
welche typisch sind für Paläomethanogenese. Im Gegensatz dazu, ist die USF-1 durch einen
hohen Organikanteil und Karbonatablagerungen und siliziklastische Gesteine gekennzeichnet,
was auf eine des Meeresspiegels hindeutet.
Die USF enthält den Kerogentyp II bis II-III und zeichnet sich durch einen kontinuierlich
ansteigenden organischen Kohlenstoffanteil (TOC) und Wasserstoffindex (HI) aus. Im
zentralen Graben ist die USF durch niedrige Diasteranindices und Ts/(Ts+Tm) Verhältnisse
gekennzeichnet, was auf anoxische, tonarme oder karbonatreiche Muttergesteine hindeutet.
Im Gegensatz dazu, enthält die LSF den Kerogentyp II-III und hat niedrigere TOC und HI
Werte. Der Sauerstoffindex (OI) ist auffällig höher als in der LSF. Des Weiteren hat die LSF
relativ hohe Diasteranindexwerte und Ts/(Ts+