The Gulf of Suez is characterized by the presence
of many hydrocarbon-bearing fields including reservoirs ranging
in age from the Palaeozoic to the Tertiary. EastMorgan oil
field is one of the promising oil fields which are located in the
southern part of the Gulf of Suez and tapping hydrocarbon
deposits and potentials of the Miocene age. The purpose of
this work is to evaluate the Miocene sediments of the Asl and
Hawara Formations in East Morgan oil field (western subbasin)
through carrying out an integrated petrophysical, seismic
structural and sequence stratigraphy study. Quantitative
well logging analyses are carried out over Asl and Hawara
Formations to throw light over their hydrocarbon potentiality.
Good oil saturation is exhibited by the sand sections of Asl
Formation, and fair to good are assigned for those of Hawara
Formation in the Belayim dip province. On the other hand, a
little hydrocarbon saturation is represented by both formations
to the south of the study area in the Morgan accommodation
zone (MAZ). The estimated petrophysical parameters of Asl
reservoir throughout the study area range between 4 % and
10 % for effective porosity, 18 % and 89 % for shale volume
and 2 % and 48 % for hydrocarbon saturation. Meanwhile,
the ranges of 1–8 %, 20–98 % and 2–32 % are given for
Hawara Formation for effective porosity, shale volume and hydrocarbon saturation, respectively. The lateral distribution
maps show that the central and the western parts of the MAZ
attain the best petrophysical parameters and hydrocarbon potentiality.
Seismic facies analysis, structural framework and
depositional history of the study area were studied through
interpreting the seismic reflection data of 27 seismic profiles.
A number of geo-seismic cross sections are constructed and
interpreted to investigate the structural setting of the study area
and clarify the main structural elements that affect the hydrocarbon
bearing reservoirs. A group of simple NW–SE steplike
normal faults, parallel to the Clysmic trend, is found
cutting through the reservoir rocks at the bottom layers of
the section (Rudeis Formation) and extending upwards to
overlying layers (Zeit Formation). Some graben- and horstshaped
structures are found and usually bounded by two sets
of oppositely dipping normal step-like cross faults. The seismic
facies and sequence analysis revealed that the Miocene
rocks are subdivided into two major third-order depositional
sequences (S1 and S2), separated by two major depositional
sequence boundaries (DSB1 and DSB2). The first sequence
(S1, Lower–Middle Miocene rocks) is of prime interest, as it
encounters the main hydrocarbon reservoirs in the study area
(Asl and Hawara Formations that are equivalent to Rudeis
Formation). The seismic facies of this sequence are characterized
by low to moderate amplitude, discontinuous horizons
and bounded by the depositional sequence boundary (DSB1)
at the top. The reflection geometry at the cycle boundaries is
considered as erosional truncation, toplaps and even concordant
along the upper boundary of the cycle. The external form
of these sediments is considered as sheet-like and wedgeshaped
units. The entrapment of hydrocarbons seems to be
of a combined effect of the stratigraphic and structural elements.
It appears clear that both of the step-like structural fault
system and the lateral variation of facies are the key parameters
that control the accumulation of hydrocarbon in this area
and in East Morgan field as a whole. |
