الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The total area of Nile Delta is 26,450 Km2 of which 19, 200 Km2
inland and 7,250 Km2 offshore. The Nile Delta sedimentary build up began
in the Miocene time with a very thick section of Late Tertiary –
Quaternary, The Nile Delta sediments indicating a rapid and continuous
deposition in a gradually subsiding basin. This section consists mainly of
shale with sandstone intercalations.
The study area is located approximately 90 km NE of Alexandria,
which lies offshore in the deep water (150-750 m) of the present day Nile
Delta lies between latitudes 31º 50` & 32º 03`N and longitudes 30º 19` &
30º 26`E, Sequoia is one of the major channel systems that make up the
Mid-Pliocene submarine channel complex straddles the boundary between
the Rosetta and WDDM concessions. A pre-unit agreement has been
established with cost sharing of WDDM 56%: Rosetta 44%. West Delta
Deep marine and Rosetta concessions.
The materials used in this study include collection and description of
core samples and core analysis from two wells, as well as the complete log
sets from ten wells in the study area, including the composite, Gamma Ray
(GR), Caliper, Deep and Shallow high resolution Laterolog resistivity
(RLA5, RLA1), Photoelectric factor (PEF), and porosity tools (Density,
Neutron) In the form of (LAS Format), Also some of the drilled wells have
some advanced wireline log like ECS, CMR and FMI logs.
The available seismic data consists of sixteen seismic lines in the
study area are interpreted in the terms of structural features. The result is
the mapping of these features in the term of faults and surfaces on the El
Wastani formations.
The seismic data represented also by some seismic attributes between
the base and the top of the channel and some seismic time slice every 10ms
from the base to the top of the channel and 3D Relative Acoustic
Impedance (RAI) cube.
A review of the available previous geological and geophysical studies
as well as internal reports of oil companies is helpful to study the general
IP computer programs for the quantitative estimations of the
subsurface sequence have been used; Also Perel Software has been used for
mapping and 3D modelling purpose.
Reviews of the available previous geological and geophysical studies
as well as internal reports of oil companies are helpful to study the general
stratigraphic column of the Nile Delta with special emphasis on the study
field.
The exploration wells Sapphire-1 and Sapphire-2 was the first two
wells targeting Sequoia Channel as a primary target, those wells operated
by the Rashid Petroleum Company (Rashpetco), were drilled using the
Atwood Oceanics semi-submersible ‘Eagle’ in 2000
The Rosetta-8 and Rosetta-10 location were chosen to appraise the
South Sequoia gas field in 2002, approximately 5km to the north, and will
penetrate the south, up dip portion of the Sequoia Channel within the
Rosetta Concession.
Sequoias D1 till Sequoia-D6 wells are development wells drilled in
2008 as a first phase of development, The Northern 3 wells will be tied into
the existing Sapphire M2 manifold in WDDM concession, whereas the
Southern 3 wells will be tied into the Rashid-3 manifold in Rosetta
concession.
Stratigraphic column of the Nile Delta is ranging in age from
Mezozoic to recant, Is represented by the Tineh Formation of Late
Oligocene/Early Miocene, which consists of very thick series of marine to
fluvio-marine shale and sandstone interbeds, The Qantara Formation has
been dated as Early Miocene,. It is equivalent to the Moghra Formation in
the Western Desert. The formation is delineated overlying the Tineh/Dabaa
formations (Late Oligocene) and underlying the Sidi Salim Formation. The
Qantara Formation is made up of calcareous shale with sandstone and
limestone streaks that deposited in a variety of coastal littoral to inner sublittoral
environment and it may rank to a coastal lagoonal one, The
Qawasim Formation Tortonian – Messinian in age forms an angular
unconformity over the Sidi Salim Formation. Early Miocene represented by
the Abu Madi Formation, Early to Late Pliocene is represented by the Kafr
El Sheikh Formation that started with the deposition of the Early Pliocene
sediments during marine flooding, The Late Pliocene to Early Pleistocene
is represented by El Wastani Formation that was deposited as a regressive
sequence after a starvation event of the Kafr El Sheikh Formation, The Late
Pliocene to Early Pleistocene is represented by El Wastani Formation that
was deposited as a regressive sequence after a starvation event of the Kafr
El Sheikh Formation and Pleistocene – Holocene Age is represented by; the
Mit Ghamr and Bilqas formations.
Sequoia channel lies at the base of the El Wastani Formation at a
similar level to the many slope channels laying in the same play in the
offshore Nile Delta area, Sequoia is a combination stratigraphic/structural
feature with dip-closure along the northern and southern margins and
stratigraphic closure (channel margin pinch-out) along the whole length of
the reservoir.
El Wastani Formation claystone form the seal to the sequoia field. The
Sequoia reservoir can be best interpreted in terms of a Pliocene deep-water
canyon fill deposited on a delta-front slope. It lies along strike from a
number of analogous canyon systems which constitute the reservoirs of the
WDDM succession. They are broadly age-consistent with a cyclic
succession of deltaic sequences that are gas-bearing in the Rosetta
concession
The Nile delta sub divided into two sub provinces by a faulted hinge
line oriented WNW to ESE allocated in Kafr El Sheikh Latitude city. This
hinge line is known as the faulted flexure that is separating the south delta
province from the north delta plain basin, this hinge is the most significant
structural feature of the Nile Delta region and is known as the faulted
flexure. It separates the Southern ridge from the Northern Delta basin. The
different structural trends are East- Northeast of Late Cretaceous to Eocene
age and those Syrian arc folds
The Nile cone is a recent phenomenon when compared with other
major deltas; The Nile Delta can be subdivided into the following structural
sedimentary provinces (A) The South Delta province, a continuation of
Western Desert stratigraphic sequences and structure, The North Delta
basin, The Nile cone and The Levant platform.
Third Chapter presents the Facies architectural by using wireline data
also discussing the results of the structural and sedimentological
interpretation of a Schlumberger FMI (Fullbore Formation MicroImager)
and conventional core data from wells Rosetta-10 and Sapphire-1 in
Sequoia Field, also the integration this data with the available seismic
data to build a depositional model representing the studied area.
Two facies models were introduced, a simple facies model derived
from only wireline data by using a SQM (self-organizing map), and
advanced facies model by integrated wireline, Image and core data.
The Self Organizing Maps (SOM) module uses a mathematical
technique to enable data to be organized into groups to produce a map.
The SOM is calibrated so used to output a facies type curve (similar to the
Cluster Analysis module), GR, Neutron and Density were used in SOM
module to produce a simple facies model consist of three main facies
(Sand, Shale and silt).
An Advanced facies model was created for integration of the wireline,
Core and FMI correlation to produce a range of depositional facies
that are consistent with a deep marine setting. They include six facies:
1- Massive sandstones witch highly resistive images do not show any
internal fabrics. The dynamic normalized images also tend not to show any
internal sandstone fabrics. This does suggest these sandstones are
structureless, minor amounts of shale clasts may appear preferentially
aligned. The structureless nature of the sandstone suggests relatively rapid
deposition, which has precluded the formation of primary sedimentary
structures, minor alignment of rare mudclasts indicates that a minor
fractional component of sediment transport has occurred. The core example
for this facies is from Rosetta-10 well and indicates structureless sandstone
showing no notable laminations. Some possible dewatering structures are
notable (lighter yellow). Some clay flecks (mudclasts) are also seen in this
core, the log response for this facies represented by GR 5-70 API, Newton
0.4-1 frac. and density 1.75-2.0 g/cc.
2- Laminated sandstone, regularly laminated sandstones are readily
identified. Laminations observed are on a millimetre-scale and comprise
relatively sandy layers and alternating conductive and resistive layers.
Mud clasts are dark in color and are generally elongate. Laminations may
appear sub-horizontal or be inclined up to 10. Truncation surfaces are
common within these sands suggesting a degree of amalgamation. The core
example for this facies is from sapphire-1 showing alternating dark and
light bands representing shale-rich and shale poor layers. The log response
for this facies represented by GR 5-70 API, neutron 0.4-1 frac. and density
1.75-2.0 g/cc.
3-Massive shale mudrocks appearing speckled with occasional
incomplete laminations. The core example for this facies is from sapphire-
1. Dark greenish gray in color with some light gray, sub-blocky-blocky,
micro carbonaceous, micaceous, fossiliferous. The mudstone facies
association generally represents low energy depositional conditions where
sedimentation is dominantly from the suspension fall-out. The log response
form this facies represented by GR 60-120 API, neutron 0.5-1 frac and
density 1.75-2.0 g/cc.
4- Laminated Shale, In-situ mudrocks appearing relatively conductive
with up to 5 cm thick appears moderately laminated. Laminations
observed are probably the result of fine-scale grain size variations of
variation in the detrital clay content of generally silt-grade deposits. This
lithofacies are the background sediments in this region, and generally this
type of interval is used to estimate local structural dip. It is assumed these
deposits are deposited on a near-horizontal basin/slope floor. The core
example in this facies is from Sapphire-1 and show fine-grained sediments
divided into what appear to be normally graded packet of 2-3 cm scale.
This would suggest deposition by diluting turbidities. Some of thicker,
sandier layer possibly show ripple laminations also: reworking by bottom
currents or by a persistent trailing tail of turbidity current. The log response
for this facies is represented by GR 60-120 API, Neutron 0.4 – 0.6 frac. and
density 2.1 – 2.3 g/cc.
5- Silt, Comprises a mixture of lithofacies types including fine grained
sandstones, siltstones and mudrocks. This facies association indicates the
relatively fast rate of sedimentation from silty-muddy high concentration
turbidity currents. Rip-up mud clasts are the result of post-depositional
processes including fluidization of the sand and sand injection, the core
example in this facies is from Sapphire-1 and show Greenish gray, light,
slightly calcareous, micaceous, micro carbonaceous, dominantly thinly
CHAPTER 8 SUNNARY AND CONCLUSION
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laminated, locally massive appearance, commonly micro deformed with
common and injected (sand dykes and sills), the log response for this facies
is represented by GR 30-80 API, neutron 0.5-0.3 frac and density 1.8-2.3
g/cc
6- Thin Bed, A lithofacies identified where sandstones show welldeveloped
internal fabrics with relatively steep dips. In addition, the
dipping fabrics may be truncated at the tops to isolate a cross-bed set,
Cross-bedding is generally not a common feature associated with turbidite
successions, and in many cases is thought developed by reworking rather
than primary deposition. The little clay material is notable in this
lithofacies suggesting a degree of winnowing/reworking of clay-laden
turbidite sands., the core example for this facies is from Sapphire-1 and
show Normally graded thin sands with parallel lamination or cross
lamination, and occasional isolated starved ripple forms, the log response
for this facies is represented by GR 15-55 API, Neutron 0.3 – 1.0 frac. and
density 1.8 – 2.0 g/cc.
The Sequoia reservoir is a heterogeneous succession of sandstones
and mudstones organized into a broad upward-fining succession. Highquality,
blocky sands occur at the base, while the upper part of the
stratigraphy is characterized by apparently isolated sandbodies encased in
thin-bedded sands and mudstones. It is important to note that despite the
apparent isolation of some sands MDT and geochemical data suggests
vertical communication through the reservoir. The base of the reservoir is
defined by a major incision surface, which has irregular topographic relief
and results in a number of perched aquifer accumulations along the length
of the field.
Concerning the concept of sequence stratigraphy, the overall Pliocene
imaged interval in Sequoia channel, may put within the canyon fill and
only one complete third order sequence and the third sedimentary unit
represents a part of another sequence can observe from interpreting FMI
image interval.
Fourth chapter represents well logging, analysis: Explain how the
Interactive pertophysics program (IP) worked, explain available data for
this study, explain equation that is generally used to measure properties
petrophysical and explain equation that we used in the current study. Was
the work of some examples of some wells in the study area, such as raw
data and corrected, the methods used to calculate the volume of the shale
and the methods used to calculate the porosity, as well as to determine the
water saturation and hydrocarbon saturation and explain method in which
calculating the volume of the shale.
Fifth Chapter Represent Reservoir Evaluation: A comprehensive
formation evaluation was carried out for the Late Pliocene Sequoia
Channel, section encountered in the ten selected wells in the study area.
Reservoir evaluation, that represents the main task in the present work, is
conducted to evaluate the petrophysical parameters needed for formation
evaluation. It includes, the determination of the volume of shale, porosities
(total, secondary and effective), lithologic composition (shale and sand)
and fluid saturation (water and, oil, gas,) for the studied members using the
IP software for the quantitative estimations of the subsurface sequence. The
output results are presented in two vertical plots, of the same depth scale,
for each well. The first plot illustrates the corrected log data and the second
one is a litho-saturation plot. Determine the contact between gas zone and
water zone (GWC) can be easily recognized from the relation between the
neutron, density and the response of resistivity logs. Moreover, a number of
crossplots relationships have been constructed to help identification type of
the lithology, the value of the porosity and in addition to the gas and clay
effect, Results of well log analysis were used in the evaluation of the
hydrocarbon potential in the study area.
log analysis and interpretation of Sequoia Channel show one main unit
reservoir unit start mainly with silt and thin bed section with some shale
barrier at the top of the channel and at mid and bottom part of the channel
is consists of a thick sand bodies interbedded with thin beds, silt and shale,
Sequoia channel have a wide thickness variation between the channel core
and channel edges and between the channel proximal part at south to the
channel distal part at north , maximum recorded thickness (208 ft.) at
Rosetta-8 well where it hits the core of the channel, the minimum recorded
thickness (45.5 ft.) are Sequoia-D6 where the channel thickness reduced
due to the faulted area and also due to the well is tended from the core of
the channel, in general team the thickness of sequoia channel is high along
the channel core and reduced toward the channel edges .
The petrophysical parameters computation and results of the reservoir
rocks are represented by a number of isoparametric maps, which include:
volume of shale, total porosity, effective porosity, water saturation,
hydrocarbon saturation, reservoir and net to gorss thicknesses. These maps
had been interpreted as follows:
a) The volume of shale contour map of the Sequoia Channel shows
variation in shale content values minimum value of (18 %) in Sequoia-D6
well to a maximum value of (32 %) in Sequoia-D2 well. Generally the
shale content distribution decreases from the core of the channel toward the
levee of the channel along the channel axis of the study area.
b) Total porosity distribution map of Sequoia Channel Shows
variation in porosity values of minimum value (26 %) at Sequoia-D2 well
to maximum value (36 %) at Sapphire-1 well. This map shows an increase
in the total porosity from levee of the channel to the core of the channel
along the axis of the channel. While the highest valve of total porosity is
concentrated along the axis of the channel. While the effective Porosity
Distribution Map of the Sequoia channel Shows the minimum value of (19
%) in Sequoia-D2 well and maximum value of (29 %) in Sapphire-1 well,
generally the effective porosity is an increase in the core of the channel and
decrease in the edge of the channel.
c) Water saturation map of Sequoia Channel shows variation in water
saturation values minimum value of (27 %) in Sapphire-2 well to a
maximum value of (76 %) in Sequoia-D2 well. Generally the water
saturation distribution increases from the core of the channel toward the
east edge of the channel along the channel axis. While the hydrocarbon
saturation map shows variation in hydrocarbon saturation minimum value
of (24 %) in Sequoia-D2 well to a maximum value of (73 %) in Sapphire-2
well.
This map shows that the hydrocarbon saturation distribution,
decreasing away from the core of the channel toward the levee of the
channel
d) The net to gross distribution map of the Sequoia Channel shows a
considerable net to gross is concentrated in the core of the channel,
decreasing toward the edge of the channel along the channel axis of the
study area, with a maximum recorded net to gross value is 0.6 m at
Rosetta-8 well at the core of the channel, The net to gross decreases
gradually from central to both direction of the channel, recording the
minimum net to gross value at Sapphire-2 well where the well is located in
the levee part of the channel in the southern distal part of the channel
Sixth chapter introduces an advanced interpretation method for the
thin bed intervals which the conventional method of interpretation cannot
evaluate it in a proper way.
Anisotropy is the variation of properties with direction, is common in
sedimentary strata, where the pore structure allows the current to flow more
easily parallel to the bedding plane than perpendicular to it (many solid
particles have flat or elongated shapes that are usually oriented parallel to
the plane of deposition). The notation Rh is used to represent the resistivity
in the direction parallel to the bedding plane and Rv to represent the
resistivity normal to the bedding plane. Particle shape anisotropy is most
commonly found in shale.
When logging perpendicular to bed boundaries, resistivity tools read
the effective horizontal resistivity Rh, which can be calculated from the
volume average of the layer conductivities (inverse resistivity).
Traditionally, LaSSI interpretation is used resistivity tensor model;
Resistivity tensor model characterizes resistivity anisotropy using
horizontal and vertical resistivity from triaxial multicomponent induction
tool MCI
The integration leads to better evaluate thinly bedded intervals in a
large clastic reservoir. The application of different technologies to better
evaluate thinly bedded intervals. Magnetic resonance was used to better
define the free fluid portion of the reservoir, and to delineate permeable
sections. Water base mud imaging was utilized to characterize the bedding
and resistivity anisotropy measurements were integrated using standard
published techniques that led to a better evaluation of the thinly bedded
intervals. These technologies allowed for the evaluation of different
approaches to the reservoir evaluation. These approaches did not change
the conventional evaluation in thick clean reservoir zones and intervals
with dispersed clay. In thinly bedded intervals our evaluation led to a better
estimate of reservoir potential. The presence of gas in these thin beds
intervals can be approved if the samples were taken against these intervals.
The Porosity, Hydrocarbon saturation and Net pay thickness for the all
Sequoia channel wells has been increased with a different percent based on
the laminated and the thin bed interval for each well, porosity increased by
13 percent, hydrocarbon saturation increased by 24 percent and the net pay
increased by 68 percent.
Seventh chapter discusses the 3D geological model construction, the
3D geological model was constructed using Petrel software and using for
the integrating different types of input data. All data of formation tops, well
header information, well logs, seismic interpretation (faults and surfaces,
attributes and seismic cube) and petrophysical parameters (facies, shale
volume, net to gross thickness, porosity, permeability, fluid saturation,
formation and member level tops set) were used during this study.
The 3D geological model workflow comprises mainly the structural
modeling and the property modeling. The structure model includes fault
framework and horizon modeling processes. Top Sequoia channel, bas
Sequoia gas and bas Sequoia channel interpreted seismic surfaces and were
used in the horizon modeling process in depth domain. The property
modeling process was performed to populate the reservoir facies and
properties such as (porosity, permeability and fluid saturation) as extracted
from the available petrophysical analysis inside the structure model. The
model represents a detailed zonation and layering configuration for the
Sequoia channel.