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The AAPG/Datapages Combined Publications Database
Journal of Petroleum Geology
Abstract
Journal of Petroleum Geology, vol.
HYDROCARBON
GENERATION AND CHARGING OCTOBER FIELD, GULF OF SUEZ, EGYPT
M. A. El-Ghamri1, I.C. Warburton2 and S.D. Burley2&3
1Geology Dept., Faculty of Science, Alexandria University, Egypt. email: [email protected]
2Exploration and Development Geoscience, BG Group, UK. email: [email protected].
3Basin Dynamics Research Group, University of Keele, UK. email: [email protected]
Source rocks on-structure in the October field are not sufficiently mature to have expelled
hydrocarbons at the present day. 1-D modelling of a pseudo-well in the deep October
South Trough demonstrates that the Eocene Thebes and Senonian Sudr Formations are
presently mature at depths greater than 3km. However, only the carbonate-rich Sudr
Formation has generated sufficient hydrocarbons for expulsion
to take place at depths
shallower than 3.5km, suggesting that reservoired oil in the October field originates
predominantly from source rocks of this unit. Model results indicate that
hydrocarbon
expulsion
from this source may have commenced as early as 20Ma in kitchen depocentres
adjacent to the October field, and continued through the Pliocene.
Migration
routes predicted from 2-D modelling are complex and require downward
expulsion
from the Sudr Formation east and west of the October field to charge the
Palaeozoic Nubian Sandstone. Mature Sudr Formation in the October South Trough first
charges the Nubian and then lower Senonian Matulla Formation reservoirs in the NW
compartments of the October field via flow across the NW bounding fault. The mature
Sudr Formation in the Baba Trough to the SE charged the Matulla Sandstones on the
eastern flanks of the October field which then back-filled to spill into the Nubian Sandstones.
Hydrocarbons generated from the Thebes Formation contribute only minor volumes to
the predicted accumulations.
The presence of trap-bounding faults and their sealing properties is shown to be a key
sensitivity for charging the October field and related structures. Fault seal is required to
charge known accumulations and match known hydrocarbon
column heights, but extending
shale smear into the Nubian Sandstone prevents the crestal October field structure from
charging.
The Matulla Formation sandstones are a regional migration
fairway providing charge
for the Ras Budran field and Nubian Sandstone prospects to the west of the October field.
Younger Mesozoic sandstones are charged by vertical
migration
through seals and along
faults. This regional
migration
sequence as described for the October field is likely to
apply to other tilted fault-block structures in the Gulf of Suez and provides a regional
predictive exploration concept. Back filling and spilling beneath sealing faults is likely to
be the characteristic charging mechanism for the Nubian Sandstones in this setting.
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