الفهرس 
Geologic SettingOnly 14 pages are availabe for public view
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Abstract
The area under study is the West Al-Khilala Field, which is a
Messinian (Late Miocene) gas field, located in the southern part of the
Onshore Nile Delta, North West El Mansoura concession, Egypt. The main
objective of this study is the delineation of the structural and stratigraphic
features, and the formation evaluation of the Messinian Abu Madi reservoir.
These are carried out through the classical interpretation of seismic data and
conventional electrical logs, then applying seismic inversion techniques, to
get much more information about the Messinian Abu Madi reservoir.
Geologically, West Al Khilala Field is controlled by two major
normal faults trending NW-SE, down throwing to the east. It shows an
elongated four-way dip closure trending NW-SE, parallel to the main eastern
bounding faults.
The available data for this study is twenty 2-D post-stack seismic
sections and wireline logs of four wells, which are not sufficient to perform
a detailed study of the structural and stratigraphic features, as well as
reservoir characterization analysis for West Al-Khilala Field. So, it is needed
to resample the given 2-D seismic lines into a 3-D grid, this resampling
process was carried out using Petrel 2017.1 software.
The first interpretation step is the seismic to well tie, to define the
formation tops and the interested horizons to be picked. The traced faults
across the field are normal faults, with the trend of NW-SE and a down
thrown side to the east. Then, applying several stratigraphic and structural
seismic attributes on the resampled 3D volume and have several time slices
on the attributes volumes, to track the trend of the Abu Madi gas-bearing
Summary and Conclusions
145
sandstones channel across West Al-Khilala field, which is in the NW-SE,
parallel to the normal faults trend.
Then, time depth conversion is applied, using the velocity model as
needed to have geologic interpretations at depth, relative to the elevation
datum. To build an accurate velocity model, first, we calibrated the sonic
logs with checkshots for each well in West Al Khilala Field, using spline
calibration technique. This checkshot times are used, to correct the sonic log,
that used as input to generate synthetic seismograms, instead of the original
sonic log. The sonic and surface seismic data were measured at different
frequencies, due to the dispersion effect. This process is based on the
assumption that, the check shot times are representative of the correct
velocity. By building the velocity model, it can be displayed and used to
convert the produced maps from time to depth domains.
Then, three types of seismic inversion techniques are carried out,
these are: Colored, Model-Based and Sparse-Spike seismic inversions. The
results are analyzed, to determine the gas-bearing sand zone of Abu Madi
channel, that had high acoustic impedance, as appeared on the inversion
results. The inversion algorithms used in this study was depending only on
the post-stack seismic data, which helped in tracking the gas-bearing
sandstone channel, depending on the low acoustic impedance values. The
results of this study support the idea that, seismic inversion can enhance the
interpretability of the given data and gives a feasible approach to obtain
reservoir delineation, better than the conventional seismic interpretation. So,
we can say that, post-stack seismic inversion successfully identified and
delineated the gas sand reservoir in the study area.
Summary and Conclusions
146
Then, the well log data recorded from four wells in West Al Khilala
Field (West Al Khilala-2, West Al Khilala-4, West Al Khilala-5 and West
Al Khilala-6) are analyzed. It can be used to track the change in thickness
and petrophysical parameters, like, porosity, gas saturation and net-pay
thickness variations of Abu Madi Formation, where these variations are due
to the depositional environment conditions. from this study, we can follow
the lateral variations of the petrophysical characteristics, added to the
acoustic impedance values, that represented in iso-parametric maps. The
petrophysical characteristics of Abu Madi Formation reflect the ability of
these rocks to store and produce hydrocarbon fluids. The measured effective
porosity ranges between 9.1 and 19.8%, the shale volume content ranges
from 19.8 to 63.7% and the hydrocarbon saturation ranges between 9 and
30.2%, which reflect the characterization of the studied reservoir to be a gas
charged reservoir.
Recommendations
For the future prospection, the following recommendations are made:
Perform a 3-D interpretation of all the sandstone bodies, using the PreStack seismic inversion techniques.
Execute AVO analysis to delineate the expected fluid types, using PreStack seismic cubes.
Carry out a detailed study of the petrophysical parameters of the
interested reservoirs, using core samples to adequately evaluate the
reservoir intervals and to compare the reservoir parameters from logs
with those derived from core data.
Drilling another new wells at the high acoustic impedance zones
depending on the acoustic impedance model