Principles of petroleum geology m.m.badawy

3 Petroleum Geology, (M.M.Badawy)
Petroleum Geology

PETROLEUM GEOLOGY
 Petroleum geology is the branch of economic geology that relates to the
Origin, Migration and Accumulation of oil and gas and to the Discovery of
commercial deposits.
WHAT IS PETROLEUM?
• Legally, petroleum has been called a Mineral, but this usage does Not satisfy
the common geologic definition of a mineral as an Inorganic substance.
• It has also been called a Mineraloid, a term also applied to chalcedony and
amber, on the ground that it is not definite enough in Chemical Composition.
• It is frequently called Mineral Fuel, along with peat and coal.
• Petroleum is a Fossil Fuel.
THE DEVELOPMENT OF PETROLEUM GEOLOGY:
• The Oil Seepages
• The Anticlinal Theory
• Subsurface Geology
• Geophysics
• New Methods

THE OIL SEEPAGES:
• The first petroleum fields were discovered Near oil seepages.
• A petroleum seep Is a place where liquid or gaseous hydrocarbons escape
to the surface through fractures and fissures in the rock and between
geological layers. Petroleum seeps Are quite common: California has
thousands of them. Much of the petroleum discovered in California during the
19th century was from observations of seeps.
HOW OIL SEEP WAS FORMED?

THE ANTICLINAL THEORY:
• The theory was that because Oil is lighter than Water it would Seek the
Highest part of an underground structural fold. Thus, an Anticline is a
more Favorable place to Drill for oil than Syncline.
THE ANTICLINE TRAP:

SUBSURFACE GEOLOGY:
• The study of the information Revealed by the Boreholes already drilled and
from the Study of the Sedimentary story as revealed in well and surface
sections showed that Oil Accumulations could be found by tracing Lateral
changes in rock composition, Locating breaks in deposition and other ways.
Techniques for the presentation of structural and stratigraphical information
improved greatly during this time.
GEOPHYSICS:
• The Torsion balance for gravity measurements had been introduced in 1920
and the seismograph in 1923.
• The Chief Advantage of the Geophysical Tools is that they Allow the
operator to “look” below breaks in the geological sequence, which Masks
the formations at depth from surface geological inspection.
NEW METHODS:
BRIGHT SPOT:
• Since 1972, the application of Direct Hydrocarbon Detection by geophysical
means has forced geologists and geophysicists into each other disciplines.
• It is one of the pattern classes in a seismic section and the indicators of Gas
(hydrocarbon) accumulation.
• Gas charged sand reservoirs gave High amplitude reflection or bright spot
• Because of the High reflection coefficient of the shale-gas sand-shale
sequence, the limits of the gas field are Beautifully Described.

SEISMIC STRATIGRAPHY:
• It is the study of Stratigraphy and Depositional Facies as interpreted from
Seismic Data.
• The primary exploration Objectives in the Use of Seismic Stratigraphy is its
Assistance in the tracing of facies across wide areas.

WHAT IS PETROLEUM
Petro= Rock Oleum= Oil
Petroleum= Rock Oil
Petroleum is a complex mixture of Hydrocarbon (H, C) compound with minor
amounts of Nitrogen, Oxygen and sulfur as impurities.
Petroleum is a general term for all naturally occurring hydrocarbons present
in (liquid, Gaseous and Solid or Semisolid forms)
 LIQUID PETROLEUM – Crude Oil
 GASEOUS PETROLEUM – Natural gas or Light hydrocarbon (Methane,
Ethane, Butane...etc)
 SOLID OR SEMISOLID PETROLEUM – Tar, Pitch, Asphalt

LIQUID PETROLEUM:
 It is called crude oil to distinguish it from refined oil.
 Is the most important commercially.
 It consists of the liquid hydrocarbon with varying amount of dissolved gases,
bitumen and impurities.
 Crude Oil is measured by:
American Barrel = 42 American Gallons = 158.9 Liters
 Measured in France and Germany By:
Cubic meters m3 = 6.28 Barrels
GASEOUS PETROLEUM:
 It is called Natural Gas to distinguish it from Manufactured gas.
 It consists of the lighter paraffin hydrocarbon with the most abundant is the
Methane Gas (CH4).
 Natural Gas is measured by:
Cubic Feet or Thousand Cubic Feet

SOLID OR SEMISOLID PETROLEUM:
 It is called Asphalt, Tar, and Pitch or by any one of many other terms
depending on their individual characteristics and local usage.
 Consists of heavy hydrocarbons and Bitumen(Liquid & Solid form of
Hydrocarbon)(Soluble Organic Matter)
 Combustible Rocks Non-combustible Rocks
 Ex: Oil, Natural Gas, Coal, Oil Shale Ex: Shale
 Type of rocks which have
a high amount of hydrocarbons
CAUSTOBIOLITHES
Caustic= Hot Bio= Life Litho= Stone
CAUSTOBIOLITHES & ACAUSTOBIOLITHES
CAUSTOBIOLITHES ACAUSTOBIOLITHES

Petroleum called a hydrocarbon is a Wrong name because it has another
component like Oxygen, Nitrogen and sulfur.
SAPROPEL OIL:
 Generally like ose or slutch composed of plant remains where most of
algae or petrifying in an aerobic environment on the shallow bottom of
lakes and sea may be a source of petroleum and natural gas.
 Mud rich with organic matter.

Element Crude Oil Asphalt Natural Gas Kerogen
Carbon 82-87 80-85 65-80 79
Hydrogen 11 - 14.0 8-11.0 1-25.0 6
Sulfur 0.1-5.5 2-8.0 Trace-0.2 5
Nitrgen 0.1-1.5 0-2 1-15.0 2
Oxygen 0.1-4.5 0-2 -- 8
CHEMICAL PROPERTIES OF PETROLEUM
1) Elemental composition
2) Molecular size variation
3) Hydrocarbon series
4) The isotopes of some elements of petroleum
5) The Correlation Index (C.I)
6) Other constituents
7) Miscellaneous substances
ELEMENTAL COMPOSITION
 Petroleum is composed of C : H ( 1 : 1.85 ) (represented by~ 97%)
 The minor elements as Sulfur, Nitrogen, Oxygen (less than 3% of most
petroleum)
 Traces of phosphorus and heavy metals such as: Vanadium and Nickel.
ELEMENTAL COMPOSITION OF NATURAL MATERIAL IN
PERCENTAGE:

 With increasing the percentages of hydrogen, the specific gravity of the oil is
decrease.
 Kerogen: Organic matter in sediments with insoluble in organic solvent.
 Bitumen: soluble organic matter.
MOLECULAR SIZE VARIATION
The elements Carbon and Hydrogen are combined as hydrocarbons that vary both
in:
 The Size
 The Type of Molecules
Hydrocarbon form: Homologous Series, which about a family of molecules whose
members have similar properties and different in size by a CH2 group.
HYDROCARBON SERIES
There are four main hydrocarbon series differing in chemical properties and
relationships:
 Normal Paraffin (or, Alkenes) series
 Isoparaffin series (or, Branched Chain Paraffin)
 Naphthene (or, Cycloparaffin) series
 Aromatic (or, Benzene) series

PARAFFIN (ALKANE) SERIES:
 They are the second most common constituents of crude oil next to
naphthenes.
 Paraffin’s dominate the gasoline fraction of crude oil.
 They are the principle hydrocarbons in the oldest, most deeply reservoirs
Paraffins increase in the oldest reservoirs
Paraffins decrease in the youngest reservoirs
 The paraffin series of hydrocarbon is a saturated straight chain (Aliphatic)
 General Composition (CnH2n+2)
NAPHTHENE (CYCLOPARAFFIN) SERIES:
 The most common molecular structure in petroleum.
 The cycloparaffin formed by joining the carbon atoms in a ring.
 The napthene of hydrocarbon series is a saturated (single covalent bond)
homologous, closed-ring series.
 General Composition (formula) (CnH2n)
 Cyclopentane (C5H10) and cyclohexane (C6H12) are the chief member of the
naphthene series found in petroleum.
 Cyclopropane (C3H6) and methyl cyclopropane (C4H8) are gases at ordinary
Temperature and Pressure, But All the other monocyclic are Liquid.

AROMATIC (BENZENE) SERIES:
 The aromatic series of hydrocarbon named with this name because many of
this members have a strong aromatic odor.
 Is an unsaturated closed ring (carboxylic) series.
 General Formula (CnH2n-6).
 Benzene (C6H6): a colorless and volatile liquid, the paint and most common
member of this series.
 Aromatic are present in all petroleum but the percentage is small.
Graphical methods of representation the constituents of crude oil:
Decrease According To Abundant
Naphthenic
Paraffin’s
AsphalticAromatic
Petroleum
Aromatic (small %)Paraffinic (second
most common)
Naphthenic
(Most common)

THE ISOTOPES OF SOME ELEMENTS OF PETROLEUM
• Isotopes have the same atomic number, but they have different atomic
weight. It is distinguished stable and unstable isotopes. Non-stable isotopes
can spontaneously disintegrate with formation of new atoms with another
numbers of protons.
• In petroleum geology, it is widely using data of studies of isotopes of carbon,
hydrogen, sulfur and other elements to solve problems of genesis of oil and
gas.
THE CARBON ISOTOPES:
• Carbon has three isotopes 12C, 13C and 14C. All carbon atoms have six protons
but there are three carbon isotopes containing six, seven and eight
neutrons, giving atomic masses 12, 13 and 14 respectively.
• 12C and 13C are stable isotopes and the original forms of carbon in the earth.
Stable isotopes are useful, because the proportion of two isotopes of each
element vary from sample to sample as a result of isotope effects.

THE CARBON ISOTOPES:
• The distribution of these three isotopes in the biosphere is as follows:
14C AGE DATING:
• 14C is an unstable isotope and is formed from the bombardment of
atmospheric nitrogen with neutrons produced by cosmic radiation and
enters the biosphere as CO2.
• The 14C decays to 14N. One neutron in a 14C atom spontaneously decays,
giving off an electron (β-particle) and leaving a new proton (p).
• This produces 14N, since nitrogen atoms have seven protons in their nuclei.
The reaction is:
• 14C (6p + 8n) - β → 14N (7p + 7n)

14C AND AGE DATING:
• A mass of 14C atoms disintegrates at a fixed rate such that half of the mass is
changed from carbon to nitrogen in 5,570 years (the half-life period of
14C). Consequently, the age of a carbon containing substance can be
determined by measuring its output of β – particles.
• The technique is only good for about five half live periods (30,000 years),
because β – particle emission becomes too low in older materials to
distinguish from background noise.
13C CAN SOLVE MANY GEOCHEMICAL PROBLEMS:
• The 13C isotope is distributed through sediments of all geologic ages, in
contrast to 14C, which is limited to very young sediments.
• The difference in mass of 13C relative to 12C result in fractionation by
biological and physical processes.
• The heavy isotopes form stronger bonds than light isotopes. This
preference causes separation of heavy and light isotopes at equilibrium.
• For example, in the oceans CO2 is in equilibrium with various carbonate
species.

HOW CAN 13C SOLVE MANY GEOCHEMICAL PROBLEMS?
• CO2 + H2O → CO2-- + 2H+
ENRICHED IN 12C ENRICHED IN 13C
• The ratio of 13C (heavy isotope) to 12C(light isotope) is determined on an
isotope ratio mass spectrometer.
• The ratio difference δ 13C = [(13C /12C sample)/ (13C /12C standard) - 1] x
1000 in 0/00 relative to standard
• The standard that has been used most widely in the literature over the years
is a belemnite from the Pedee Formation in South Carolina (PDB).
THE FOLLOWING TABLE SHOWS THE VARIATION IN 13C IN SOME NATURAL
MATERIAL:

THE ISOTOPES OF OTHER ELEMENTS:

CORRELATION INDEX
 This correlation index is useful in classifying the oil as a qualitative.
 The correlation index: Is a number of a magnitude indicates certain
characteristics of the crude oil distillation fraction.
 The paraffin give a C.I of Zero & benzene is about 100
 The lowr C.I value of analysis fraction, the greater concentration of paraffin
hydrocarbon in fraction.
 The higher C.I value, the greater concentration of Naphthenic and
Aromatic hydrocarbon.
Smith Equation:
C.I = (48640/K) + (473.7G)-456.8
Where:
K = the average Boiling Point of the fraction in 0K
G = Specific Gravity of the fraction at 600F
‫دﻟﯾل‬‫اﻟﻣﺿﺎھﺎه‬
‫اﻟﺗرﺗﯾب‬ ‫ﺣﺳب‬ ‫ﻟﻠﺗواﺟد‬ ‫ﻧﺳﺑﺔ‬ ‫اﻛﺑر‬ ‫ﺣﺳب‬ ‫اﻟﺑﺗرول‬ ‫ﻣﻛوﻧﺎت‬ ‫ﺑﯾن‬ ‫وﺗﻧﺎﺳب‬ ‫ﻧﺳﺑﺔ‬ ‫ﻋن‬ ‫ﻋﺑﺎرة‬...

OTHER CONSTITUENTS
Sulfur:
 (0.1-5.5)% in crude oil.
 The presence of sulfur and sulfur compounds in gasoline causes: (corrosion –
bad odor – poor explosion)
‫ﻓﯾﮭﺎ‬ ‫اﻟرﻏوب‬ ‫ﻏﯾر‬ ‫اﻟﻣواد‬ ‫ﻣن‬ ‫وﯾﻌﺗﺑر‬ ‫اﻟﺑﺗرول‬ ‫ﺟودة‬ ‫ﻣن‬ ‫ﯾﻘﻠل‬ ‫اﻟﺳﻠﻔر‬ ‫ﺗواﺟد‬
 The percentage of Sulfur:
Sulfur, Low Crude Oil called: Sweat
Sulfur, High Crude Oil called: Sour
 Note:
- With increasing of Sulfur, specific gravity of oil increase (Bad Thing)
- With increasing of Hydrogen, specific gravity decrease (Good Thing)
Nitrogen:
 (0.1-1.5)% in crude oil.
 All crude oil contain small quantities of nitrogen.
 Nitrogen is a common constituents of natural gas (1-15)%
 Nitrogen which exists in crude oil may be existing in dissolved gases.
 Nitrogen is an unwanted component of both crude oil & Natural Gas.

Oxygen:
 (0.1-4)% in crude oil
 Oxygen occur in various forms:
- Free oxygen
- Phenols (C6H5OH)
- Fatty acids
- Naphthenic acids (CnH2n-1.CooH)
- Asphalt Substances
MISCELLANEOUS SUBSTANCES
 Crude oil contains minute amount of a wide variety of miscellaneous
components.
 Some organic and some of inorganic
Organic materials:
 Are seen under microscope
 Includes:
- Siliceous skeletal test
- Petrified wood fragments
- Spores – coal
- Lignite fragments (Coal type)
- Algae and unicellular organism

Inorganic materials:
 May observe in the ash (Oil burning)
 Elements that have been identified in crude oil ash include:
(Si – Fe – Al – Ca – Mg – Cu – Pb – Tin – Arsenic – Antimony – Zn – Ag – Cr –
Molybdenum – Ni – V)
 Nickel and Vanadium: are concentrated in porphyrins and replace the
magnesium in chlorophyll.
 Ni & V: are very important, because the Ni/V ration in crude oil is greater
than in the earth’s crust, so they are using to correlate crude oils and the
oil to source rock place.
 Porphyrins: large complex of N, S, O compounds derived from chlorophyll,
which used as a biomarker in the indication of the origin of the oil and the
source rock.

PHYSICAL PROPERTIES OF PETROLEUM
• They allow determining their commercial quality. Some parameters are
using for estimating and planning of the exploitation of oil fields, the
transporting and others.
• Many problems of the geological history of petroleum are determined with
data obtained from measuring the physical parameters of oils and its
variations with depths in the sections and along the area of oil province.
THE DENSITY AND SPECIFIC GRAVITY:
• The density of substance is the weight of a given volume.
• A convenient method of expressing the same physical property is the
specific gravity in which no units of measurements need to specify.
• Specific gravity is the ratio of the weights of equal volumes of the
substance and pure water at certain temperature and pressure.( Unitless)
Weight per volume
Unit: (gm/cm3)

The API GRAVITY:
• The API gravity scale is an arbitrary one, which has the advantage the
simplifying the construction of (hydrometers), because it enables the stems
to be calibrated linearly.
• API gravity does not have a straight-line relationship with specific gravity,
nor with the other physical properties correlated with specific gravity such as
viscosity.
• High values of API gravity correspond to low specific gravity. A similar scale
is the European Baume´ gravity scale.
HOW TO CALCULATE DEGREES API?
American Petroleum Institute (Degrees
of Gravity)
‫ال‬ ‫ﺑﯾﻘﯾس‬ ‫ﺟﮭﺎز‬specific gravity

• 10° API is equivalent to a specific gravity of one.
• The specific gravity of crude petroleum ranges from 0.7 (API 70.6°) for very
light crude oils, up to more than one (API 10°) for some solid bitumen.
• Most crude oils are being in range of 0.82 (API 41°) to 0.87 (API 31°).
• The gravity of two crude oils may differ considerably even though the oils
seem related closely.
• There may be a difference in gravity between oils in adjacent reservoirs
within the same field or geologic environment, between oils in the same
reservoir rocks but in separate traps, and between oils within the same
reservoir but of differing structural position.
BOILING POINT:
• Oil consists of a closely related series of complex hydrocarbon compounds
that range from gasoline to heavy solids. The various mixtures that
constitute crude oil can be separated by distillation under increasing
temperature into such components as (from light to heavy) gasoline,
kerosene, gas oil, lubricating oil, residual fuel oil, bitumen, and paraffin.
High (API) ….. Low (Specific gravity) …. (Good Type) High Paraffin
Low (API) …… High Specific gravity …. (Less Type) High Naphthenic & Aromatic

BOILING POINT:
• The boiling points of hydrocarbons are depending on their compositions. The
more carbon atoms in the molecular structures of hydrocarbons are the
higher boiling temperature. The naphthenic and aromatic hydrocarbons,
in which carbon atoms are linking in rings, have boiling temperatures higher
than paraffinic hydrocarbons with the same numbers of carbon atoms.
CLOUD AND POUR POINTS OF PETROLEUM:
• The cloud point is the temperature at which the first cloud appears in oil. It
is due to the settling out of solid paraffin wax; wax-free naphthenic oils
show no cloud point.
• The pour point—the temperature below which crude oil becomes plastic
and will not flow—is important to recovery and transport and is always
determined. Pour points range from 32° C to below -57° C.
‫ﻓ‬ ‫ﻧﻘﻠﺔ‬ ‫ﻓﻲ‬ ‫اﻟﺑﺗرول‬ ‫ﯾﺗﺟﻣد‬ ‫ﻻ‬ ‫ﺣﺗﻲ‬ ‫ﺣﺳﺎﺑﮭﺎ‬ ‫وﯾت‬ ‫اﻟﺗﻌﻛر‬ ‫او‬ ‫اﻻﻧﺳﻛﺎب‬ ‫درﺟﺔ‬‫اﻟﻣواﺳﯾر‬ ‫ﻲ‬

VISCOSITY:
• It is an inverse measure of the ability of a substance to flow, the greater
the viscosity of a fluid, the less readily it flows.
• Crude oils vary greatly in viscosity. Some, such as natural gas and light oils
are very mobile. Others are highly viscous and these grade into the
semisolid petroleum, although the latter are more strictly speaking plastic.
• Viscosities vary directly with the composition. the greater the number of
carbon atoms in a member of a hydrocarbon series, the greater will be its
viscosity
SURFACE TENSION:
• It is the force necessary to increase the free surface of certain liquid by
one square centimeter, without changing temperature of the liquid
(Unit dyne /cm2).
• Surface tension results from the action of molecular force, which differs
from one liquid to another. The force of cohesion of molecules of liquid with
hard body may exceed the force of cohesion between the molecules of
liquid.

OPTICAL ACTIVITY:
• It is the power to rotate the plane of polarized light. This is measured with
a polariscope in degrees per millimeter, and the average range is from 0 to
1.2 degrees (almost to the right i.e. dextrorotary).
• All crudes either are optically active or contain optically active distillation
fractions, particularly in the intermediate range (250-300° ).
WHY THE ORGANIC SUBSTANCES HAVE OPTICAL ACTIVITY?
• It is thought that optical rotary power is confined to organic substance.
Cholestrin (cholesterol), which is alcohol with the formula (C26 H45 OH), is
found in both vegetable and animal matter and it is a constituent of new
milk from fresh cattle.
• Optical activity is commonly given as an argument for the origin of
petroleum from plant or animal remains, because as far as we know,
optical active oils cannot be synthesized inorganically.

COLOR:
• The color of petroleum by transmitted light varies from light yellow to red;
some very dark or black oils are opaque. The higher the specific gravity (or
low the API gravity), is the darker the oil.
• The cause of the color is not known, but it is thought to be related to the
aromatic series of compounds. By reflected light, the crude oil is usually
green because of its fluorescence.
LUMINESCENCE AND FLUORESCENCE:
• Luminescence is the emission of light by some oils that have received
energy.
• Fluorescence is a type of luminescence. All oils exhibit more or less
fluorescence, the aromatic oils being the most fluorescent. The fluorescent
colors of crude oils range continuously from yellow through green to blue.
This property is used in the logging of wells to locate oil showing in the core
and cutting samples and drilling mud.
• Fluorescence is rapidly reduced by aging, so that fresh oil is easily
distinguished from oil previously caught in the drilling mud. Fluorescence is
observed under ultraviolet radiation

ELECTRICAL PROPERTIES:
• Oils are dielectric, so the electrical methods are using for discovering oil-
bearing beds in the well.
COMBUSTION HEAT:
• Oils have exceptionally high combustion heat. The data of combustion heat of
coal, oil and gas are as follows in joules/kg
• Coal 33600
• Oil 43250-45500
• Natural gas 37700-56600
FLASH AND BURNING POINTS:
• The flash point is the temperature at which the vapors rising off the
surface of the heated oil will ignite with a flash of very short duration
when a flame is passed over the surface. When the oil is heated to a higher
temperature, it will ignite and burn with a steady flame at the surface.
• The lowest temperature at which this will occur is known as (the burning
point). These measurements are a measure of the risk involved in handling
and storing petroleum and petroleum products, and state law generally fixes
their limits.

REFRACTIVE INDEX:
• The absolute Refractive Index (RI) of a substance is the inverse ratio of the
speed of light in that substance to its speed in a vacuum.
• The refractive index is defined as the ratio of the sine of the angle of
incidence to the sine of angle of refraction; both angles are being
determined with respect to a normal to the surface.

THE ORIGIN OF PETROLEUM
• This problem has puzzled geologists for a long time.
• Many theories have been proposed to explain the origin of petroleum, but none
has proved to be convincing.
• In general, the (Early theories) were based on laboratory experiments that
attempt to simulate field conditions.
• The more (Recent theories) are based on modern analytical method,
especially carbon isotope geochemistry.
• Theories of the origin of petroleum may be divided into two groups according
to their view of the primary source material as (organic) or as (inorganic).
• Early ideas have tendency toward the inorganic source, where as the
modern theories assume that the primary source material was organic.
• The theory of origin has a bearing on the method of exploration.

THE GEOLOGIC FENCE OF ORIGIN OF PETROLEUM
LIMITING CONDITION OF ORIGIN OF PETROLEUM
 All hydrocarbons occur in sediments of marine and continental origin.
 Petroleum is extremely complex mixture of many hydrocarbons. No two
crudes are similar; however the elemental chemical analyses are similar.
 Petroleum is formed in rocks from the Precambrian to the Pleistocene,
although the occurrences in some ages are anomalous.
Upper Jurassic shale's dominate as a source rock in the Northwest European
sedimentary basins and as much as 25% of the world’s hydrocarbons may come
from this interval.
The type locality of the Kimmeridge Clay Formation is along the Dorset coast of
England.
 Until the advent of chromatographic and similar tools, no bitumen had been
found in (shale's and carbonates). Insoluble organic matter (kerogen) was
found in the sediments.
 The temperatures of petroleum reservoirs range from 1070C in some deeper
reservoirs. The presence of porphyrins in some hydrocarbons indicates that
such crude oils have never exceeded 2000C, for porphyrins are destroyed at
lower temperature.

 Porphyrins: Large, complex N,S,O compounds derived from chlorophyll and
related molecules. There exist several homologous series of porphyrins that
can be useful as biomarkers.
 Biomarkers (Chemo fossils): Chemical compounds derived from specific
biological precursors. They used as environmental and maturity indicators.
 Anaerobes: They are organisms (esp. bacteria) that can live in the absence of
free oxygen OR they are sediments that exist only in the absence of free
oxygen.
 The origin of petroleum is within an anaerobic and reducing e environment.
The presence of porphyrins means anaerobic conditions developed early in
life of petroleum.
 No differences have been observed between oil pools formed due to
migration and that have not affected by migration.
 The time required to form petroleum and concentrate it into pools is probably
less than one million years.

INORGANIC OR ABIOGENIC PETROLEUM ORIGIN
 A small number of geologists adhere to the A biogenic petroleum origin
hypothesis and maintain that hydrocarbons of purely inorganic origin exist
within Earth's interior.
 Chemists Marceline Berthelot and Dmitri Mendeleev, as well as
astronomer Thomas Gold championed the theory of a biogenic origin.
 Carbide Hypothesis: It assumes that deep in the earth exist metal carbides
that form hydrocarbons on contact with hydrothermal solutions.
Fe C2 + 2H2O → HC CH + Fe (OH)2
Iron Carbide Acetylene
At elevated temperatures, the acetylene polymerizes to form benzene.
 Cosomic Hypothesis: Hydrocarbons were present in the earth’s
atmosphere when it was in molten form. As a result of solidification of the
earth, the hydrocarbons were condensed and accumulated in the earth
crust.

 Really methane is proved to exist in the atmosphere of some planets, but
the existence of more complex hydrocarbons in thermodynamic conditions
of firely liquid substance is impossible.
 The Abiogenic origin hypothesis has not yet been ruled out. Its advocates
consider that it is "still an open question”.
 Extensive research into the chemical structure of kerogen has identified
algae as the primary source of oil.
 The lack association of petroleum with volcanism.
 The Abiogenic origin hypothesis fails to explain the presence of these
markers in kerogen and oil, as well as failing to explain how inorganic
origin could be achieved at temperatures and pressures sufficient to
convert kerogen to graphite.
 It has not been successfully used in uncovering oil deposits by geologists, as
the hypothesis lacks any mechanism for determining where the process
may occur.
 More recently scientists have found that ethane and heavier hydrocarbons
can be synthesized under conditions of the upper mantle.

ORGANIC OR BIOGENIC ORIGIN OF PETROLEUM
 According to generally accepted theory, petroleum is derived from ancient
biomass.
 It is a fossil fuel derived from ancient fossilized organic materials. The
theory was initially based on the isolation of molecules from petroleum that
closely resemble known bio molecules.
 Structure of vanadium porphyrin compound extracted from petroleum by
Alfred Treibs, father of organic geochemistry. Treibs noted the close
structural similarity of this molecule and chlorophyll a

MOLECULAR STRUCTURES OF LIVING ORGANISMS:
All living things are formed from a few simple, molecular building blocks that have
changed relatively over geologic time.
• Carbohydrates: (They are not the important sources of the petroleum,
collective name for sugars and their polymers)
• Proteins: (They are high order polymers from individual amino acids and
account for the most of N,S components in organisms)
• Lipids: (Are one of the main sources of petroleum, These cover all organisms
produced substances that are insoluble in water, as: Fats, Vegetable Oil,
Waxes)
• Lignin and Tannin:
(Both are characterized by aromatic structures. They are common in plant
tissues).
(The aromatic content of petroleum is derived from Lignin and Tannin)
(Characterized by their aromatic structure, (Phenol))

THE RATIO OF CARBON ATOM TO THE N, S, AND O ATOMS:
AVERAGE CHEMICAL COMPOSITION OF LIFE SUBSTANCES:

COMPOSITION OF LIVING MATTER:
WHAT IS THE MOST IMPORTANT PROGENITOR OF PETROLEUM?
• The lipids content of all forms of organic matter is more than enough to
account for the origin of petroleum.
• It is shown that less than 1% of the organic matter in sediments is required to
form all the known petroleum.
• Lipids are more resistant to degradation in a reducing environment than
proteins and carbohydrates.
• Lipids may be the most important progenitors of petroleum

Diagenesis Catagenesis Metagenesis
MATURATION OF ORGANIC MATTER
DIAGENESIS OF ORGANIC MATTER:
 It is the process of biological, physical and chemical alteration of the organic
matter before a pronounced effect of temperature.
 Covering the temperature range from surface (250c) to about (500c).
 When organisms die, their organic matter undergoes a variety of reactions.
Some micro biological: such as the formation by anaerobes.
Some physical and chemical: such as dehydration and oxidation.
 The combined attack of weathering and microbes convert much of organic
matter either to gases that escape into atmosphere or to soluble products that
are carried by ground water.
Note: Environments that preserve large amount of organic matter in the sediments
are stagnant lakes and sill basins where the bottom waters are strongly reducing.
Examples:
 Black sea (organic content of the sediment exceeds 15%.
 Red clay of oceanic abyssal plaints (where slow rates of deposition, aerobic
waters so little organic matter result in sedimentary organic contents of less
than 0.1%

 Oil is formed from organic matter deposited in the aerobic waters of
sedimentary basins, where the water occasionally may be anaerobic but the
sediments are nearly always anaerobic. As (the formed in aerobic condition
and reducing environment)
 The more resistant organic matter including: (humid materials, resins, waxes,
lipids)
 The organic content of such sediments with mean source beds of petroleum.
(ranges between (0.5 – 5) % with mean around 1.5%
Note:
Major source rock in age of Cretaceous (organic rich mud sediments)
Organic matter occurs with burial at depth range where temperatures are too low for
cracking of large molecule to occur.
The organic matter deposited in sediments consists primarily of the biopolymers of
living organisms. (As, carbohydrates, protein, lipids, lignin and subgroups such as
waxes, fats ….. etc)
If we will say the source rock it must has an organic matter percentage of (0.1 to 1.5)
% so, Red sea or Red clay does not called a source rock

Notes:
 Polymers: A large molecule consists of many small subunits.
 Biopolymers: polymers created by enzymes, they have very regular
structure.
 Geopolymers: polymers formed in the geosphere as the result of chemical
combination of small molecules, they have irregular structure, and they are
not susceptible to microbe attack.

CATAGENESIS OF ORGANIC MTTER
 It is the process by which organic matter is altered due to the effect of
increasing temperature (50-200)0c.
 The compaction of sedimentary basins causes the organic matrix to be
subjected to increase at higher temperature with greater depth of burial.
 In a reducing environment: This increasing the temperature causes the
thermal degradation of kerogen and associated organic compound to form
petroleum range hydrocarbons.
 The Term of catagenesis was proposed by (Vassoevich 1959)
 Temperature may range from (50-200)0c
 Geostatic pressure due to overburden may vary from (300-1500) bars.
 Depth of oil window (1.5-7.5) Km.

During catagenesis composition and texture of the mineral phases are conserved
with some changes mostly in clay fraction, the main inorganic modification still
concerns the compaction of the rock:
 Water continues to expel.
 Porosity and permeability decreases.
 Salinity of interstitial water increases and may come close to saturation.
Changes of organic matter:
 Through progressive evolution the kerogen produces first liquid petroleum
then in later stage (wet gas) and condensate, are accompanied by significant
amount of methane.
 The end of catagenesis is reached in the range where the disappearance of
aliphatic carbon chains in kerogen completed and where the development of
an ordering of basic kerogen units begins.
 This corresponds to (Vitrinite Reflectance of about 2), which according to
various coal classifications is approximately the beginning of anthracite ranks.
(Vitrinite is a type of coal which can detect the paleotemperature by
knowing the temperature)

METAGENESIS OF ORGANIC MATTER:
 The last stage of the evolution of sediments with is known as metamorphism
and is reached in deep troughs and in geosynclinals zones.
 Petroleum geology is only concerned with this stage as metagenesis of organic
matter.
 Minerals are transformed under those conditions and lose their interlayer
water and gain a higher stage of crystalline:
(Iron oxide with water ----------- Iron oxide without water)
(Goethite) (Hematite)
 The rock reaches temperature conditions that leads to the metagenesis of
organic matter, (organic matter is composed only of methane and a carbon
residue)
 Temperature range (200-300)0c

TIME AND TEMPERATURE IN ORIGIN OF PETROLEUM
 The rates of chemical reaction are affected by temperature
(Temp-increase …………… Reaction rate-increase)
 Increases in temperature of 100c can double the reaction rate.
 The relation between temperature and reaction rate is expressed by:
(Arrhenius equation)
Where: K = A e-(Ea/RT)
K = the reaction rate constant related to change in concentration of parent
substance with change in time;
A = frequency factor;
Ea = activation energy
R = gas constant;
T = temperature in degrees Kelvin
The A factor is a constant representing the frequency with which molecules
collide in a proper orientation to enable a reaction to occur. The activation energy
(Ea) is the amount of energy that must be absorbed by a molecule or molecular
complex to break the bonds and form new products.
 Maturation of organic matter depends on Time and Temperature.
 There are limits for time and temperature at petroleum is formed in economic
quantities.
 Each source rock forms oil and gas at different rate with increasing
temperature is depending on:
o It’s content of the various types of kerogen.
o The possible catalytic of its mineral constituents.

OIL WINDOW OR THE PRINCIPLE PHASE OF OIL GENERATION
Oil Window: (Interval)
 The depth interval in which a petroleum source rock generates and expels
most of its oil.
 OR, it’s a vertical representation of the generative interval.
Hydrocarbon Kitchen: (Area)
 The area that supplied the hydrocarbon for these respective structure, and
conceder the deepest place in the basin (source rock) (Pod of active source)
(center of the basin).
SIGNIFICANCE OF OIL WINDOW:
 Exploration geologists can predict the probability of oil and gas in sedimentary
basin.
 Oil is not generated in young-cold basin, because temperature are not high
enough to indicate the threshold of intense oil generation (limit interval
between Dia and Cata, Cannon 1974).
 No hydrocarbons are being generated in old-hot basins, because they are
destroyed.
 The places to prospect are the (young-hot) or (old-cold) basins

SOME MOLECULES STRUCTURES:

FORMS OF HYDROCARBONS:
 Dry gas- contains largely from >99.9% methane gas.
 Wet gas- contains methane with contributions from ethane propane, butane
with minor constituents from pentane gas.
 Condesates- Hydrocarbon with a molecular weight such that they are gas in
the subsurface where temperatures are high, but condence to liquid when
reach cooler to the surface temperatures.
 Liquid hydrocarbons- commonly known as oil or crude oil.
 Plastic hydrocarbons- asphalt
 Solid hydrocarbons- coal and kerogen- (kerogen strictly defined is
disseminated organic matter in sediments that is insoluble in organic solvents.
 Gas hydrates- Solids composed of water molecules surrounding gas
molecules, usually methane, but also H2S, CO2, and other less common gases.

Brent Crude Oil:
Is a major trading classification of sweet, light crude oil that serves as a major
benchmark price for purchases of oil worldwide. The Brent Crude oil marker is also
known as Brent Blend.
‫اﻟﻌﺎﻟﻣﻲ‬ ‫اﻟﻧﻔط‬ ‫إﻧﺗﺎج‬ ‫ﺛﻠﺛﻲ‬ ‫ﻟﺗﺳﻌﯾر‬ ‫ﻛﻣﻌﯾﺎر‬ ‫ﯾﺳﺗﺧدم‬ ‫ﻧﻔطﻲ‬ ‫ﺧﺎم‬ ‫ھو‬ ‫ﺑرﻧت‬ ‫ﺧﺎم‬‫اﻷورو‬ ‫اﻷﺳواق‬ ‫ﻓﻲ‬ ‫ﺧﺎﺻﺔ‬,‫واﻷﻓرﯾﻘﯾﺔ‬ ‫ﺑﯾﺔ‬
.‫ﻓﯾﮫ‬ ‫اﻟﻛﺑرﯾت‬ ‫ﻧﺳﺑﺔ‬ ‫اﻧﺧﻔﺎض‬ ‫ﺑﺳﺑب‬ ‫اﻟﻧوﻋﻲ‬ ‫وزﻧﮫ‬ ‫ﺑﺳﺑب‬ ‫اﻟﺣﻠوة‬ ‫اﻟﺧﻔﯾﻔﺔ‬ ‫اﻟﻧﻔط‬ ‫أﻧواع‬ ‫ﻣن‬ ‫وﯾﻌﺗﺑر‬

Three studies showing the distribution of the world’s oil source rocks in the
stratigraphic record:

The distribution of the world’s oil and gas source rocks in the stratigraphic
record:

OIL & GAS
ACCUMULATION

PETROLEUM SYSTEM ELEMENTS
There are FOUR necessary elements to form an oil and gas accumulations:
 GENERATION
 MIGRATION PATHWAYS
 ACCUMULATION
 TRAPPING AND SEALING MECHANISM
RESERVOIR ROCK
Reservoir rock is a rock that can store and transmit the accumulated hydrocarbons.
These rocks made mainly of porous and permeable sandstone, limestone or
dolomite. The hydrocarbons are situated in the void spaces or the connected pores
between the grains.
RESERVOIR TRAPS
RESERVOIR TRAP consists of an impervious stratum that overlies the reservoir rock
that prohibiting hydrocarbons from escaping upward and laterally. This impervious
stratum is called a roof rock (CAP ROCK). The roof forms a seal, or a barrier, which
creates the needed conditions for a pool. Trap material must have a lower
permeability than the existing rock material though which the hydrocarbons are
flowing.

SEALING ROCK
A type of rock adjoining the reservoir rock that restricts the leakage of hydrocarbons
from a trap after it has been accumulated.

HYDROCARBON RESERVOIR TRAPS
There are three basic types of hydrocarbon traps depending on the elements of
entrapments according to the classification proposed by Levorsen (1967):
 Structural Reservoir Traps
 Stratigraphic Reservoir Traps
 Combination
STRUCTURAL RESERVOIR TRAPS
They are formed by tectonic processes AFTER deposition of the reservoir beds.
There are THREE types of structural traps:
1. Folded Reservoir Traps: resulted due to bending (deformation) of the rock units
without breaking. The simplest form is the domal or anticlinal structure creating
anticlinal traps
2. Faulted Reservoir Traps: These are the result of fracturing (breaking down)
within the rock units where one side has moved relative to the other side. Faulting
may be the sole cause of the formation of this type of trap.
3. Folded - Faulted Reservoir Traps: Faulting may be combined with other
structural features such as folding.
4. Fractured Reservoir Traps: Crystalline carbonate rock (Limestone) with non
recognizable texture of interlocking crystals of calcite giving fracturing upon
dolomitization. These fractures increase the original porosity and permeability of the
carbonate rocks (limestone or dolomite) and become an excellent trap for oil and gas
accumulations.

STRATIGRAPHIC RESERVOIR TRAPS
They are created when a change in lithology or lithofacies (which also controls
porosity and permeability), DURING or AFTER the deposition of reservoir beds.
1. Primary Stratigraphic Traps :
Traps are formed DURING the deposition of the reservoir beds as:
(1) Sandstone Lenses (2) Channel Fillings
(3) Offshore Sand Bars
(4) Coral Reefs (Bioherms and Biostromes)

2. Secondary Stratigraphic Traps :
Traps are formed AFTER the deposition of the reservoir beds (traps associated by
Unconformities)
• Angular Unconformity
• Nonconformity
• Disconformities

COMBINATION TRAPS
The geometry of the combined trap is the result of a combination of TECTONIC
PROCESSES and change in LITHOLOGY (porosity and permeability). An example of a
combination trap is a salt dome.
The salt dome is a mass of rock salts (Gypsum or Anhydrite) generally of a diameter
about 2 km near the surface. This mass of salt has pushed upward through the
surrounding rock and sediments into its present position. Salt beds were formed by
the natural evaporation of sea water from semi closed to closed basins.
Origin of Salt Dome Traps (diapers) :
The origin of salt domes is best explained by NETTLETON (PLASTIC FLOW
THEORY). Salt has a density of 2.2 gm/cm3 under standard conditions. But at a depth
of about 12,000 feet, the mass of the overlying sediments exerts a compressive,
downward force, density decreases and salt begins to flow like a plastic substance. A
small fracture in the overlying, higher density sediments (PIERCEMENT SALT
DOMES) or a slightly bending of the overlying (NONPIERCEMENT SALT DOMES).

RESERVOIR PETROPHYSICS
The fundamental property of a reservoir rock is its porosity and permeability. Both
POROSITY and PERMEABILITY are geometric properties of a rock and both are the
result of its litho logic composition.
POROSITY:
• Total Porosity: is the percent of the total pore spaces between the rock grains
(Connected + Unconnected (T %) .
• Effective Porosity: is the percent of the connected pore spaces between the
rock grains (E %) .

Factors Affecting Porosity:
• Grain Size of Rock Materials
• Pattern Arrangement
1. Cubic Packing (E %)=47.6%
2. Rhombohedral Packing(E %)=25.9%
• Grain Shape and Sorting
Reservoir classification depending effective porosity:
• Effective Porosity (E) >15% (Reservoir of Great Capacity)
• Effective Porosity (E) 5-15% ( Reservoir of Average Capacity)
• Effective Porosity (E) <5% (Reservoir of Low Capacity)

PERMEABILITY
• The ability, or measurement of a rock's ability to transmit fluids, typically
measured in (darcies or millidarcies). Formations that transmit fluids readily,
such as sandstones are described as permeable and tend to have many large,
well-connected pores.
• Impermeable formations, such as shales and siltstones, tend to be finer grained
or of a mixed grain size, with smaller, fewer, or less interconnected pores.
• Good reservoir rocks have both good porosity and good permeability.
Reservoir classification depending Permeability:
• Permeability >1 Darcy (Reservoir of Excellent Permeability)
• Permeability 0.1-1 Darcy (Reservoir of Good Permeability)
• Permeability 0.01-0.1 Darcy (Reservoir of Average Permeability)
• Permeability <0.001 Darcy (Reservoir of Negligible Permeability)
BARREN TRAPS
• Traps are formed after the migration of hydrocarbons
• There is no source rocks in the basin
• There is no sealing mechanism
• Deformation of traps due to the rejuvenation of the tectonic earth movement.

RESERVOIR DYNAMICS
Oil and gas accumulations in the reservoir traps are affected by two important
factors and considered the most important sources of reservoir energy which make
the reservoir in a dynamic state:
 Pressure
 Temperature
RESERVOIR PRESSURE:

SOURCES OF ABNORMAL PRESSURE:
1. Rapid geologic loading (deposition) or unloading (erosion), it means the pressure
resulted from the rock overburden.
2. Vertical and side sealing of reservoirs.
3. Earthquakes.
4. Regional compressive (squeezing) or tensile (stretching) tectonic stresses.
5. Pressure of ground water flow (Fluid Flow).
6. Osmotic Pressure.
7. Cementation and Dissolution.

RESERVOIR TEMPERATURE
It is well known that the oil generation window conditions are usually takes place at
depth ranges between (2.5 to 6.5) km that equivalent to temperature of (60 to
160)oC.

SOURCES OF TEMPERATURE:
1. Magmatic eruptions.
2. Heat of radioactivity.
3. Heat conductivity of minerals and rocks.
4. Increasing the depth of burial (Overburden).
Effect of Temperature on Reservoir Dynamics:
 Increasing of temperature lead to decreasing the oil viscosity
 Increasing of temperature lead to increasing the volume of oil and gas
according to Charl,s Law Vtc= (1/273)Vo
 Increasing of temperature lead to increasing the pressure of fluids especially
(oil and gas) in reservoir.
 Increasing of temperature lead to decreasing the gas solubility in oils and
consequently the formation of free gas cap.
 Increasing of temperature lead to increasing the solubility of salts in formation
water lead to good separation of oil and formation water.

CRUDE OIL RECOVERY
Oil Recovery is classified into THREE types:
Primary recovery:
This type depends ONLY the using of natural energy of reservoirs, typically
recovers up to 50% of oil in Place through:
- Free Gas Cap Drive
- Water-Gas drive (Combination Drive)
- Formation Water Drive
- Gas Lift

Secondary Recovery:
Involves ADDING energy to the natural system by injecting water or gas to
maintain pressure and displace oil. Typical recoveries are 25-45% Oil in Place after
primary recovery through:
 Injected water or CO2 to displace hydrocarbons.
 Pumping (Suck erode Pumping or Submericible Pumping)

Tertiary recovery:
Includes all other methods used to increase the amount of oil recovered. Typical
recoveries are 5-20% of oil in place after primary and secondary recovery
Chemical injection (HCl), Thermal injection (steam) and Solvent injection
Maximum Efficient Rate (MER):
It is the maximum rate at which a well or field can be produced without loss of
reservoir energy or leaving bypassed oil in the reservoir
Productivity Index (PI):
It is the number of daily barrels produced every pound/square inch from the
pressure of reservoir

STAGES OF PROSPECTION AND EXPLORATION FOR OIL
AND GAS DEPOSITS
Successful oil and gas exploration and development generally progresses through
FIVE basic operational phases include:
(PHASE 1): PRELIMINARY (GEOLOGIC) INVESTIGATIONS:
The geological investigation method depends mainly on remote sensing, aerial and
satellite photographs and the mapping of outcrop rocks in addition to the oil seepage
that can give indications of the presence of subsurface oil and gas accumulations.
This phase includes:
 Reconnaissance Survey by using large scale maps (1:1,000,000)
 Detailed Survey by using small scale maps (1: 1000)
This phase aims to exclude the litho logic basement outcrops or thin
sedimentary cover, identifying the target area and the road and building
constructions.

(PHASE 2): GEOPHYSICAL INVESTIGATIONS:
Gravity Surveys is used to detect the variations in gravity caused by the differences
in the density between the basement (Igneous and Metamorphic) and sedimentary
rock types.
Seismic Reflection Survey is the most common indirect method used for locating
subsurface structures that may contain oil and gas deposits.
Shock waves are induced into the earth using one of several methods. These waves
travel downward and outward encountering various strata, each having a different
seismic velocity. Sensing devices called geophones are placed on the surface to detect
these reflections. The geophones are connected to a data recorder, which stores the
data.

(PHASE 3): EXPLORATION DRILLING:
1. The site of the first exploratory well is determined based on the existing state
of knowledge of underground conditions and the topography of the terrain.
This is generally sited vertically above the thickest part of the stratum thought
to contain hydrocarbons. This narrow-bore hole (with a diameter of 20-50
centimeters) is generally sunk to a depth of between 2,000 and 4,000 meters. It
may go beyond 6,000 meters.
2. The presence of suspected oil and gas deposits may be confirmed by
exploratory (wildcat) drilling of deep holes.
There are THREE systems for exploration drilling:
1: Profile Drilling
2: Triangulation Drilling
3: Radial Drilling

(PHASE 4) FIELD DEVELOPMENT & PRODUCTION DRILLING:
After the completion of the first exploratory well (wildcat well) as a commercial
producer marks the beginning of the development of an oil and gas field.
A Field Development Plan consists of a coordinated collection of sufficient
information about the development of the field. Sufficient information may not be
available until one or more confirmation wells have been drilled to delineate the
characteristics of the reservoir. The limits of a field located on a structural trap can
be determined more easily than a stratigraphic field based on the information
obtained from drilled wells and geophysical data.
The subsurface information includes:
1. Expected depths of gas-oil and oil-water contact zones.
2. The anticipated pressures in the formations to be drilled.
3. Structure configuration of reservoir and its extension.
Production is a combination of operations that includes:
1. Bringing the fluids (oil, gas, and water) to the surface
2. Maintaining and/or enhancing the productive capacity of the wells
3. Treating and separating the fluids
4. Purifying, testing, measuring, and preparing the fluids for marketing
5. Disposing of produced water
6. Transporting oil and gas to market.

(PHASE 5) GEOCHEMICAL EXPLORATION:
1- Before Drilling:
 Surface geochemical exploration of soil sediments for hydrocarbon
investigation.
 Geochemical analysis of oil and gas seeps.
2- After Drilling:
 Geochemical analysis of the extracted rock samples either ditch or core for
source rock evaluation and biological marker distributions.
 Geochemical analysis of crude oils for biomarker characterization.
 Infer the correlation between crude oils and source rock attributes.

STOCK RESERVE CALCULATIONS
Reserve are the amount of oil and gas that can be produced from a well or field in the
future under current economic conditions using the current technology.
Reserves are always reported in stock tank barrels of oil and standard cubic feet of
gases.
1 Barrel of Oil = 158.99 Liters
Stock Oil Reserves (bbls)
Oil reserve can be computed volumetrically for a single well or an entire oil field as
follow:

Stock Gas Reserves (Cubic Feet)

OIL PROVINCES OF EGYPT

Crude Oil Production and Consumption:
 In 2007, Egypt produced 664000 barrels of oil per day (bbl/d) continuing its
fall from a high of 950000 bbl/d in 1995. Yet having consumed 653000 b/d in
2007.
 Production was sufficient to prevent Egypt from becoming a net importer of oil
(Oil and Gas Journal August, 2008)
Natural Gas Production and Consumption:
 Egypt's natural gas sector is expanding rapidly with production having
increased over 30% between 1999 and 2007. In 2007, Egypt produced 1.7
trillion cubic feet (TCF) and consumed 1.1 TCF of natural gas.
 Egypt’s estimated proven gas reserves stand at 58.5 TCF, or roughly 1% of the
world reserves. Egypt is on its way will become a leading supplier of natural
gas throughout the Mediterranean region.
‫ﻗ‬ ‫ﺑﺳﺑب‬ ‫واﯾﺿﺎ‬ ,‫اﻻﻧﺗﺎج‬ ‫ﻣن‬ ‫اﻛﺑر‬ ‫اﻻﺳﺗﮭﻼك‬‫ﻠﺔ‬
‫اﻟطﺑ‬ ‫ﺑﺎﻟﻐﺎز‬ ‫واﻻھﺗﻣﺎم‬ ‫اﻟﺗوﺟﺔ‬ ‫ﻧﺗﯾﺟﺔ‬ ‫اﻻﻧﺗﺎج‬‫ﯾﻌﻲ‬

 Egypt is considered among the pioneer countries in which oil was discovered
as (surface seepage in 1886 in Gebel El-Zeit area along the west coast of
the Gulf of Suez.)
 Egypt produced an average of about 594,000 barrels per day (bbl/d) of crude
oil in 2004, down sharply from its peak of 922,000 (bbl/d) in 1996, but only
modestly below the 618,000 (bbl/d) produced in 2003.
Egypt is subdivided into four main petroliferous provinces:
GULF OF SUEZ.
WESTERN DESERT.
NILE DELTA & OFFSHORE MEDITERRANEAN SEA.
NORTHERN SINAI.

GULF OF SUEZ
The Gulf of Suez contributes by 50% of the overall production of oil in Egypt. It is
considered as NW-SE intracratonic rift basin formed during Pre-Cambrian and
rejuvenated during Oligocene and classified into THREE provinces according to
the INCLINATION OF STRATA AND FAULT TRENDS:
1. Northern Province
2. Central Province
3. Southern Province
‫اﻟﺑرﯾ‬ ‫ﻓﻲ‬ ‫اﻟرﯾﻔﺗﻧﺞ‬ ‫ﻋﻣﻠﯾﺔ‬ ‫ﻋن‬ ‫ﻧﺎﺗﺞ‬ ‫اﻟﺳوﯾس‬ ‫ﺧﻠﯾﺞ‬‫ﻛﺎﻣﺑرﯾﺎن‬
‫اﻟﻌﻘﺑ‬ ‫ﺧﻠﯾﺞ‬ ‫اﻣﺎ‬ , ‫اوﻟﯾﺟوﺳﯾن‬ ‫ﻓﻲ‬ ‫ﻟﻠﺣرﻛﮫ‬ ‫اﻋﺎده‬ ‫وﺣدﺛت‬‫ﺣدث‬ ‫ﺔ‬
‫ﻣﻠﯾو‬ ‫ﺧﻣﺳﺔ‬ ‫اواﺧر‬ ‫ﻓﻲ‬ ‫ﻓوﻟت‬ ‫ﺳﻠﯾب‬ ‫اﻻﺳﺗرﯾك‬ ‫ﻧﺗﯾﺟﮫ‬,‫ﺳﻧﺔ‬ ‫ن‬
‫واﻟﺟﻧوﺑﻲ‬ ‫اﻟﺷﻣﺎﻟﻲ‬ ‫واﻟﺟزء‬‫ﻣﺗﻔﻘﯾ‬ ‫اﻟﺳوﯾس‬ ‫ﺧﻠﯾﺞ‬ ‫ﻓﻲ‬‫اﺗﺟﺎه‬ ‫ن‬
‫اﻻوﺳط‬ ‫اﻟﺟزء‬ ‫ﻋﻛس‬ , ‫اﻟطﺑﻘﺎت‬ ‫وﻣﯾل‬ ‫اﻟﻔوﻟﺗﺎت‬

LITHOSTRATIGRAPIC SUCCESSION OF THE GULF OF SUEZ

SOURCE ROCKS
Many workers have dealt with the problem of oil generation in the Gulf of Suez
Province.
They concluded that the sedimentary section of the Gulf of Suez contain multiple
intervals which exhibit source rock characteristics.
These intervals consist of fine clastics and carbonates and represented by the
following formations:
 Nubia-B (Lower Carboniferous)
 Brown Limestone of Sudr Formation (Upper Cretaceous)
 Esna Shale (Paleocene)
 Lower Miocene shale (Rudeis Formation)
Their content in total organic carbon contents ranges between 1% to more than
6.5%, which classified the source rock to be good to excellent potential source rocks.
OIL BEARING ROCKS & FORMATIONS
Most of the Gulf of Suez oil occurs in porous sandstone and fractured limestone
constituting the following formations:
 (Nubia A and C) consists of porous and permeable sandstone
 (Thebes’s formation) of Middle Eocene age, it is presented by cherty and
flinty limestones.
 (Nukhul Formation) of the basal Miocene age, represented by reefal
limestone in some areas and clastic sequence in another area from the
Gulf of Suez.
 (Rudeis Formation) of sandstone interbeds with the shale intervals
forming lenses of stratigraphic traps in many of the oilfields.

CAP ROCKS & SEALING MECHANISM
The vertical sealing and cap rocks in the Gulf of Suez province occurs within the
evaporite succession constituting the Upper Miocene of Ras Malaab Group in the
following formations:
 (Belayim Formation) consists mainly from gypsum and anhydrite with
shale interbeds.
 (South Gharib Formation) consists mainly from rock salts, anhydrite with
shale interbeds.
 (Zeit Formation) consists mainly from rock salts.

WESTERN DESERT
The Western Desert of Egypt covers two thirds of the whole area of Egypt. The oil
exploration activity revealed the discovery of more than 50 oil/or gas fields.
Abu Gharadig Basin is an E-W oriented graben separates the coastal basins (Matruh,
Shushan, Dahab Mireir and Natrun basins) which formed as a result of single rift
during the Permo-Triassic age than the southern and western basins (Gindi, Diyrout
and Assiut and Faghur-Siwa Basin).
The First
Explored
Area

LITHOSTRATIGRAPHY OF THE WESTERN DESERT

POTENTIAL SOURCE ROCK
Potential source rocks for oil and gas generation have been identified in the
following stratigraphic intervals:
1. Jurassic (Khatatba Formation)
2. Lower Cretaceous (Alam El-Bueib Formation)
3. Upper Cretaceous (Abu Roash E,F &G formations)
These formations contain fair to excellent quality oil-gas prone source rock of mixed
kerogen types (II-III)
OIL–BEARING ROCKS AND FORMATIONS
Alam El-Bueib Formation contains fine grained sandstone which acts as good
reservoir rocks. These sandstones show porosity values ranging from 10-20%. This
formation produces oil and gas in Umbarka Field (44oAPI), Hayat Field (41o-50oAPI),
Safir Field (45oAPI), and Tut Field (44oAPI).
Aptian Alamein Dolomite reservoir of hard, dense vuggy dolomite of porosity
values from 3-12%. The dolomite is an oil bearing in the following fields; Alamein
(22-38oAPI), Yidma (44oAPI) and Razzak (38oAPI).

Kharita Formation reservoir of good potential reservoir rocks (porosity: 12-25%).
This formation is oil bearing in the following fields; Salam Field and Abu Gharadig
Field (36o-46oAPI).
Bahariya Formation (Cenomanian) contains good sandstone reservoirs with
porosity ranging from 18-25%. About 90% from oil and gas fields are produced from
the Bahariya sandstone such as: Razzak, Khalda, Meleiha, Salam, Amar, Yasser, Zahra,
Tut, Horus and Lotus. These fields produce oil of 34o to 50o API.
Abu Roash “G”, “F”, “D”, “C”, “B” members (Late Cenomanian) is considered the
second main reservoir rocks in the Western Desert. It contains dolomite and
limestone beds “G” with porosity 10-35% and the oil (45o API), while “F” produces
heavy crude oils (15o API). “D” produce oil (36o API). Abu Roash “C” contains
sandstone and produce oil (32 o API) in Abu Sanan and Abu Gharadig fields.

THE NILE DELTA
The Nile delta area is an emerging major gas province and considered one
of the most promising areas for future exploration in northeastern Africa.
In the last decade, exploration in the offshore Mediterranean Sea has
resulted in the discovery of significant proven reserves reached to more
than 68.2 (TCF).
The natural gases are frequently accompanied by condensates (41-56
°API), such conditions. Are present in the Nile delta and consequently
represent favorable sedimentary environments for microbial gas
generation.
Due to the large thickness of the Neogene overburden, sediments of pre-
Miocene age are seldom penetrated in the Nile delta and little is known
about their source rock potential and qualities.
Messinian Crisis (Upper Miocene), make a large amount of evaporate exist in Nile delta and Gulf
of Suez

Principles of petroleum geology m.m.badawy

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