الفهرس 
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Abstract
The study area is located offshore in the West of Nile Delta basin at Raven
field which is about 60 km offshore and to the West of the Rosetta fault. The water
depth is ranging between 500-700 m.
The theory, workflows, methodology, and results discussion integration were
the main concept of this study. Raven field in the West Nile Delta Deep Marine is
one of the best fields to apply several geophysical workflows where it has simple
geologic complexity, data availability given that it is an early development field,
the pore pressure prediction is very vital for future high pressure high
temperature (HPHT) drilling activities.
At the first stage of the study, time was spent to collect the available data
sets that would benefit the objective of this study. Also, the different approaches
were investigated to select the most recent workflows practical software,
methodologies, and terminologies to achieve results fitting to industry terms
and applications alongside with the academic understanding.
The main objectives of this study are to interpret and evaluate the seismic
multi- azimuth reflectivity dataset and pick main structure and stratigraphic elements
that could encounter overpressure to avoid While drilling. Then, the results of
seismic interpretation were used to generate attribute maps to understand the
lateral and verical distribution of the geologic elements in the study area. the
geologic understanding together with the seismic interpretation results,
attribute maps, structure models were integrated to understand the the
mechanisms of overpressure distribution at different depth levels in particular the
late Miocene age Messinian Abu-Madi Formation. Then, integrate the available
seismic and well data to estimate the pore pressure along four wells in the early
development Raven field. Finally, to
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estimate the pore pressure during the Pre-drill and While drilling then, validate with
Post drilling actual results.
In the Pre-drill stage, the tilted transverse isotropy (TTI) and Full Waveform
Inverted (FWI) seismic velocities were used in the Pre-drill prediction of the pore
pressure. A 3D pore pressure cube was built in order to identify the overpressure
areas in the overburden (OVB) across the problematic overpressured intervals in the
field i.e., Kafr El-Sheikh and Messinian to optimize the well trajectory during the
planning stage of the four wells. A detailed 1D pore pressure curve along each well
trajectory was calculated using different approaches (Modified Eaton and
PRESGRAF) in order to cover the uncertainty envelope.
In the While drilling stage, the drilling parameters i.e, ROP, WOB, ECD…
etc. were used and compared with the Pre-drill pore pressure prediction for each
well. Then the estimations were validated with the actual pore pressure data Post
drilling.
Chapter 1: This chapter discusses the location of the study area, objectives,
the available data, methods and approaches, and exploration history in the study area
from field report.
Chapter 2: This chapter covers the regional geologic setting in West part of
Nile Delta basin in particular Raven field. This chapter consists of two main sections
stratigraphic and structural settings. First, the stratigraphic units observed within
three main sequences Pre-Messinian (Langian to early Miocene), Messinian (Late
Miocene age) and Post Messinian (Late Mocene Pliocene-Pliestocene age) from
older to younger, repectively. Second, the regional structure settings that would
impact the pore pressure prediction in the West of Nile Delta basin in particular and
regional seismic lines showed the simple structure within the Raven field.
Chapter 3: This chapter focused on the main six steps workflow for seismic
data interpretation that were applied using the available reflectivity seismic data. The
main objectives from seismic interpretation were to:
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Facilitate the definition of the stratigraphic sequences across the area from
the seabed down to the reservoir section across the field.
Define the horizon framework from the seabed and down to the reservoir and
correlate with the geologic understanding.
Pick the top and the near base of the Messinian unconformity interval.
Highlight the geohazards across the study area to avoid while planning the
exploration wells or to consider mitigations While drilling them.
Utilize the depth structure maps to build a final 3D structural model. and to
generate several attribute extractions which underlined the extension of the
geobodies across the field.
Utilize the picked surfaces to generate a 3D pore pressure cube across the
area that will provide a regional understanding of the pore pressure distribution
across the field at each stratigraphic sequence.
The main aquisation parameters and processing workflow were checked from
field reports. Several seismic datasets were assessed qualitatively to compare
individual datasets based on direct visual observations and quantitatively to compare
individual datasets based on statistical parameters such as: phase, S/N, extracted
wavelets shape and stability from section to section. Based on the results from both
assessments the full stack mult-azimuth reflectivity data showed the highest S/N
ratio and phase shift less than 20° (very close to zero shift) also it is showing a
relative high-quality reliable image compared to other single azimuths. Based on that
an additional assessment was carried out to estimate the resolution, tunning thickness
and dominant frequency of that reflectivity dataset.. The chapter discussed the wellto-seismic tie analysis for three wells using the actual formation well tops to identify
the control points for horizon interpretation.
The outcome (AI) logs from the well-to-seismic tie exercise were used to
obtain a colored inversion seismic volume representing the sharp top and base to the
main lithology surfaces in the field. The following step was to define the framework
and pick the most extensive eight horizons in the area: Seabed, Plio-1, KFS, Plio-2,
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Top Messinian Abu-Madi Formation and the near base Messinian, top Serravalian
(Sidi Salem) and top Lanigan Formation (Qantara) were picked on the available
twenty seismic lines in time domain.
Finally, the time maps were converted to depth domain using Full Waveform
Inverted (FWI) seismic velocity. Petrel 2019 SLB’s software was used to generate
the results.
Chapter 4: This chapter discussed the post-stack seismic attributes theory in
details. The output surfaces generated from the interpretation workflow were used to
extract conventional seismic attribute, in addition to, apply advanced spectral
decomposition analysis. This chapter also, discussed in details the methodology and
the integrated results from both attribute types. As the stratigraphic features that
impact the pore pressure distribution for four intervals in the study area were tying
well to each other. Also, the spectral decomposition maps integration with Sum of
positive amplitudes and velocity maps at the messinian interval were robust to
highlight the anhydrites deposites across the field also provided a direct indications
to low velocity anomalies (overpressure areas).
The same integration at two Post Messinian (KFS and Plio-1) levels showed
clear fairways that impact the pore pressure regiems across the study area. It was also
highlighted that, the overpressured intervals can’t be avoided in all cases, as the
deeper reservoir can not be achieved without drilling through these problematic
zones. Therefore, the early prediction of these challenging intervals through the
integration between different attribute maps is highly recommended to asses the
required mitigations during well planning stage and drilling fluid densities
optimisation While drilling through possible overpressure zones. Petrel 2019 SLB’s
software was used to generate the attribute results.
Chapter 5: This chapter covered the fundumentals of 3D geologic modeling.
As the interpretation and attributes products were used as an input to a 3D structure
and lithology model. The petrophysical modeling and reservoir evaluation steps were
not included in the practical part as the reservoir section was out of the scope of this
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Thesis. The main results from this chapter were the 3D simulation of horizons and
faults gridding into the model and utilizing the seismic attribute maps for lithology
and facies distribution for each individual layer in the model using the property
calculator together with the lithology data along the four wells with an example from
Plio-1interval. Petrel 2019 SLB’s software was used to generate the 3D model
results.
Chapter 6: is the core chapter in this study. All outcomes from previous
chapters were integrated together for pore pressure prediction. The pore pressure
theory was discussed for the three main operational stages: Pre-drill, While drilling
and Post drilling. The available seismic velocities TTI and FWI, well logs data were
used to Pre-drill pore pressure prediction as 1D profiles along the wells.
Conventional modified Eaton approach was applied for four wells, where the normal
compaction trend (NCT) was picked manually in excel sheets using TTI and FWI
seismic data along the four wells. Then, PRESGRAF approach was applied on
techlog (SLB’s software) was used to derive the NCT based on field models using
TTI and FWI seismic velocities along the four wells. The results were compared
against each other and discussed. FWI seismic velocities was better for pore pressure
prediction compared to TTI.