Oil and Gas Analysis

Oil and gas
laboratory
analysis and
tests

content

INTRODUCTION:
CRUDE OIL:
Chemical Composition.
Chemical and Physical
Characteristics.
Classifications of Oils.
Compatibility of Crude Oils.
Tests and Laboratory
apparatus:
Sampling.
Reservoir Surface Samples.
PVT TESTS.
Chemical Standard and
Specialized tests.

Refinery Distillates Tests:
Refinery Distillates.
Refinery Distillates General tests.
Refinery Distillates Special tests.
Natural Gas:
Composition
Refinery Gas
Natural gas processing
Uses of Natural Gas
Properties and Test Methods
Sampling
Calorific Value (Heat of
Combustion)Composition

Lube Oil Tests:
Lubrication Principles.
Lubrication and Lubricants
Lube Oil production.
Characteristics of Lube Oils.
Lube Oil Classifications.
Lubricating Additives.

Sudan Crude Oil
Specifications.
Oil in Sudan
Introduction
Oil industry in Sudan
Sudan Oil Blocks
Refining and Downstream
Crude Oil General Tests for
90/10 Nile / Thar Jath Blend
Fula Crude
PDOC Crude Oil Blend
Sudanese crude Oil properties
from test result
Statistics for Crude Oil &
Productions

1. INTRODUCTION

Analytical methods
A qualitative or A quantitative
yields information
about the atomic or
molecular species
or the functional
groups that exist in
the sample.

provides numerical
information as to
the relative amount
of one or more of
these components.

Analytical methods
Classical or instrumental

A- Classical Methods
1. Semimicro Qualitative Analysis
separation of the original mixture into several parts
Each part is then subjected to an analysis of a small
number of species. In summary, the analysis involves
a set of sequenced separations and identifications.
Ex.GROUPS SEPATATION
2. Gravimetric Analysis
the unknown is precipitated from solution by a
reagent and, after separation and drying, is weighed.
3. Titrimetric (Volumetric) Analysis
we obtain the volume of a standard reagent required
to consume an analyte completely.

Spectral
Methods
Separation
Methods

Electroanalytical
methods

INSTRUMENTAL
ANALYSIS

B-Instrumental Methods

1- Classification of separation process

2. Spectral Methods:
Spectroscopy= study of the interaction of
electromagnetic radiation with matter.
When matter is energized (excited) by the
application of thermal, electrical, nuclear or
radiant energy, electromagnetic radiation is
often emitted as the matter relaxes back to its
original (ground) state.

• The spectrum of radiation emitted by a

substance that has absorbed energy is
called an emission spectrum and the
science is appropriately called emission
spectroscopy.

Electroanalytical methods:
• Electroanalytical methods are study an analyte by
measuring the potential (volts) and/or current (amperes)
in an electrochemical cell containing the analyte.
The three main categories are:
 potentiometry (the difference in electrode potentials is

measured),
 coulometry (the cell's current is measured over time),
 voltammetry (the cell's current is measured while
actively altering the cell's potential).

SAMPLING
• The value of any product is
judged by the characteristics
of the sample as determined
by laboratory tests.
•The sample used for the test(s)
must be representative of the
bulk material,

SAMPLING
• In addition, the type and
cleanliness of sample
containers are important:
• In addition, adequate records of
the circumstances and
conditions during sampling must
be made;

SAMPLING
• Solid samples require a different
protocol might involve melting
(liquefying) of the bulk material
(thermal decomposition is not
induced) followed by
homogenization.
• the protocol used for COKE sampling
(ASTM D-346, ASTM D-2013) that
are solid, for accurate analysis is
required before sale.

•
•
•
•

•
•
•
•
•
•
•

Once the sampling procedure is accomplished, the sample container should
be labeled immediately to indicate the product:
1. The location, from which the sample was obtained.
2. The identification of the location by name.
3. The character of the bulk material (solid, liquid, or gas) at the time of
sampling.
4. The means by which the sample was obtained.
5. The protocols that were used to obtain the sample.
6. The date and the amount of sample that was originally placed into
storage.
7. Any chemical analyses that have been determined to date.
8. Any physical analyses that have been determined to date.
9. The analysts who carried out the work.
10. A log sheet showing the names of the persons (with the date and the
reason for the removal of an aliquot) who removed the samples from
storage and the amount of each sample (aliquot) that was removed for
testing.

MEASUREMENT

Add
Your
Title
The issues that face Petroleum analysts
include need to provide higher quality results.

• Created By
In addition,

Follow the environmental regulations, may
influence the method of choice.

The method of choice depends on the boiling
range (or carbon number) of the sample to be
analyzed.

Each test has its own limits of accuracy and
precision that must be adhered to if the data
are to be accepted.

ACCURACY
• The accuracy of a test is a measure of
how close the test result will be to the
true value of the property being
measured.
As such, the accuracy can be expressed
as the bias between the test result and
the true value.
• The absolute accuracy can only be
established if the true value is known.

• Alternatively to approach that, we pick out
the essential tests in a specification from
the specification as a whole and extract the
essential features (termed principal
components analysis).
• Which involves an examination of set of data
as points in n-dimensional space
(corresponding to n original tests) and
determines (first) the direction that accounts
for the biggest variability in the data (first
principal component).

• The process is repeated until n principal
components are evaluated, but not all of
these are of practical importance because
some may be attributable purely to
experimental error.
• In the short term, selecting the best of the
existing tests to define product quality is the
most beneficial route to predictability.

PRECISION
The precision of a test method is the
variability between test results obtained on
the same material using the specific test
method.

The precision of an analytical method is the
amount of scatter in the results obtained from
multiple analyses of a homogeneous sample.
Precision is expressed as repeatability and
reproducibility.

• REPEATABILITY=The intralaboratory
precision or within-laboratory precision refers
to the precision of a test method when the
results are obtained by the same operator
in the same laboratory using the same
apparatus.
• In some cases, the precision is applied to
data gathered by a different operator in the
same laboratory using the same apparatus.
Thus intralaboratory precision has an
expanded meaning insofar as it can be
applied to laboratory precision.

• Reproducibility= The interlaboratory precision
or between-laboratory precision is defined in
terms of the variability between test results
obtained on the aliquots of the same
homogeneous material in different
laboratories using the same test method.
• The repeatability value and the reproducibility
value have important implications for quality.

METHOD VALIDATION
Method validation is the process of proving that an
analytical method is acceptable for its intended
purpose.
Many organizations, such as the ASTM, provide a
framework for performing such validations.
In general, methods for product specifications and
regulatory submission must include studies on
specificity, linearity, accuracy, precision, range,
detection limit, and quantitation limit.
The first step in the method development and validation cycle should be to set
minimum requirements, which are essentially acceptance specifications for the
method.
Once the validation studies are complete, the method developers should be
confident in the ability of the method to provide good quantitation in their own
laboratories.

2. CRUDE OIL

petroleum, oily, flammable fluid that
occurs naturally in deposits, usually
beneath the surface of the earth; it is
also called crude oil. It consists
principally of a mixture of
hydrocarbons, with some of various
nitrogenous sulfurous and
phosphorus compounds and traces
of heavy metals such as vanadium,
and nickel.

• that occur widely in the sedimentary
rocks in the form of gases, liquids,
semisolids, or solids.
• It is not known exactly when
humankind first used petroleum. It is
known, however, that ancient
peoples worshipped sacred fires that
were fuelled by natural gas seeping
to the surface through pores and
cracks.

FLUID DESTRIBUTION
CAP ROCKS

GAS = GAS CAP
GAS+SOME WATER
GAS +OIL

OIL + GAS

OIL
OIL + WATER
WATER + OIL
WATER
RESREVOIR ROCKS

OIL WELL

FLUID DESTRIBUTION
CAP ROCKS

GAS

GAS+ WATER
WATER + GAS
WATER
RESREVOIR ROCKS

GAS WELL

CHEMICAL COMPOSITION
• The exact molecular composition varies widely from
formation to formation but the proportion of chemical
elements vary over fairly narrow limits as follows:
Composition by weight.
•
•
•
•
•
•
•

Element
Carbon
Hydrogen
Nitrogen
Oxygen
Sulfur
Metals

Percent range
83 to 87%
10 to 14%
0.1 to 2%
CRUDE OIL
0.05 to 1.5%
0.05 to 6%
less than 1000 ppm

BASICS OF HYDROCARBON CHEMISTRY
H.C.
SATURATED

UNSATURATED

HYDROCARBONS
SATURATED
PARAFFINS

-Long Chain = normal
-Cyclic = Naphthens
-Branched = Iso-Long Chain
-Cyclic
-Branched

UNSATURATED
OLEFINS

ACETYLENS
AROMATICS

-Long Chain
-Branched
-Branched

Composition of Crude Oil

CRUDE OIL
HYDROCARBONS
ALIPHATICS
25%

C1 - C60

AROMATICS
17%

(C6H5)n

NON-HYDROCARBONS
NAPHTHENES
50%
CYCLOALKANES

SULFURS
<8%

NITROGENS
<1%

OXYGENS
<3%

<100PPM
O

SH
N
H

S

METALLICS

COOH

Crude Oil Classification

PETROLEUM
Asphaltics

Saturates
n-alkanes C5 - C44
branched alkanes
cycloalkanes (napthenes)

Aromatics
single ring
condensed ring

nitrogen
oxygen
sulfur

containing compounds

Ot he r
10%

S a t ur a t e s

A spha l t i c s

25%

8%
A r om a t i c s
7%

API Gravity = 35o
N a pht he ne s
50%

The Xylenes

CH3

CH3

CH3

CH3
CH3
ortho
Boiling Point
Melting Point

144oC
-25oC

meta
139.3oC
-47.4oC

CH3
para
137-138oC
13-14oC

Four different types of hydrocarbon molecules appear in crude
oil.
The relative percentage of each varies from oil to oil, determining
the properties of each oil.

Composition by weight
Hydrocarbon Average
Paraffins
30%
Naphthenes
49%
Aromatics
15%
Asphaltics
6%

Range
15 to 60%
30 to 60%
3 to 30%
remainder

Non-hydrocarbons

Chemical and Physical Characteristics
The appearance of crude petroleum varies
From yellow low or green colored mobile liquid

to darker and often almost black syrupy fluids
and sometimes solidifying to a black paste,
 this great variety in appearance is a obviously
caused by difference in composition .
Some oils may be particularly rich in

hydrocarbons with a low M. wt and others rich in
hydro carbons of complicated large molecules.

(1) Physical Properties of crude oil
Density : Mass per unit volume under specified conditions
of pressure and temperature, It is usually determined at
atmospheric pressure and at a temp of 15 ºC (60 ºF).

Specific Gravity : The ratio of the densities of a
substance and water under Specified conditions of
pressure and temperature and it's dimensionless
and at 60/60 ºF.
APIGravity : It refers to the API system and it has
empirical formula as follow :
141.5
ºAPI = ‫ ــــــــــــــــــــــــــــــــــــــــ‬- 131.5
Sp. gr @ 60/60 ºF

CRUDE OIL CLASSIFICATION
ACCORDING TO API Gr.

• > 45 = Extra Light (Not Useful)
• 40 – 45 = Excellent (the highest
price)
• > 31.1 = Light
• 31.1 – 22.3 = Medium
• < 22.3 = Heavy
• < 10 Extra Heavy (Bitumen)

Buoyancy
In physics, buoyancy is
the upward force that
keeps things afloat. The
net upward buoyancy
force is equal to the
magnitude of the weight of
fluid displaced by the
body. This force enables
the object to float or at
least seem lighter.

density and specific gravity of crude oil
(ASTM D-71,
ASTM D-287,
ASTM D-1217,
ASTM D-1298,
ASTM D-1480,
ASTM D-1481,
ASTM D-1555,
ASTM D-1657,
ASTM D-4052,
IP 235,
IP 160, IP 249,
IP 365)
are two properties that have found wide use
in the industry for Preliminary assessment of
the character of the crude oil.

Density

and

Relative

Density

Gravity) of Viscous Materials by

Bicapillary Pycnometer
1481

(Specific

Lipkin
ASTM D-

Density and Relative Density (Specific
Gravity)
of
Viscous
Materials
by

Bingham Pycnometer
1480

Density weighing bottle

ASTM D-

Density, Relative Density (Specific Gravity), or API Gravity
of Crude Petroleum and Liquid Petroleum Products by
Hydrometer Method D 1298

This test method covers the laboratory determination
using a glass hydrometer, of the density, relative
density (specific gravity), or API gravity of crude
petroleum, petroleum products, or mixtures of
petroleum and nonpetroleum products normally
handled as liquids, and having a Reid vapor
pressure of 101.325 kPa (14.696 psi) or less.

Digital density meter with oscillating
U-tube installed

• The oscillating U-tube is a technique to
determine the density of liquids and gases
based on an electronic measurement of
the frequency of oscillation, from which
the density value is calculated. This
measuring principle is based on the MassSpring Model.

In the digital density meter, the mechanic
oscillation of the U-tube is e.g.
electromagnetically transformed into an
alternating voltage of the same frequency. The
period τ can be measured with high resolution
and stands in simple relation to the density ρ of
the sample in the oscillator:

(B) Boiling point and Boiling Range:

• The difference in the boiling point of
individual hydrocarbons is the basis of the
dist, technique by which crude oil
fractionated into cuts of different volatility.
For all homologous series of hydrocarbons
the boiling point increases with the number
of carbon atom in the molecule. Aromatics
have, in general higher boiling point than
the corresponding apothems and paraffin's.

(C) Melting point:

• The crystatization of solid from a liquid oil
fraction seriously hampers its flow and may
give rise to blocking of lines and clogging of
filters, so melting point is very important from a
view point of oil processing and the application
of the product. The melting points of
homologues hydrocarbons increase with M.
wt. In general Iso paraffin have, in general, a
lower melting point than normal paraffins of
same number of carbon atom.

(D) Viscosity:
• Viscosity of an oil product is very important from a
technical point of view It is plays an important part in
calculation of pipelines and the design of furnaces and
heat exchangers and is further one of the leading
properties in lube oil and fuel oil and fuel oil prices are
frequently based on viscosity. Viscosity depends on the
type of components and temp. Viscosity of paraffins is
approximately a function of the density. Aromatics with a
low M .wt often have a lower viscosity than in the
corresponding paraffins, whereas the high molecular
aromatics of lube oil are more viscous than the paraffins.

Viscosity

VISCOSITY= It is a resistance of liquid layers to flow.

• F= Frictional force between two layers.
• S= Area of interface between two layers.
• dv/dx=Velocity gradient between two
layers.

F α S α dv/dx
F α S . dv/dx
F = η S . dv/dx

Viscosity coefficients(η)
• Viscosity coefficients can be defined in two
ways:
• Dynamic viscosity, also absolute
viscosity, the more usual one (typical
units Pa·s, Poise, P);
• Kinematic viscosity is the dynamic
viscosity divided by the density (typical
units cm2/s, Stokes, St).

η = Viscosity Coefficient

• The force per unit area, Vis. Dynes per
cm2, required to maintain unit difference of
velocity i.e 1 cm per Sec. between two
parrallel layers 1 cm apart.
• F = η . dv/dx
• So, if η is low Liq. Is Mobil and
• So, if η is high Liq. Is Viscous
• 1/η = φ FLUIDITY

F/S
• η=
=
dv/dx
F/S
• η=
=
dv/dx

dynes
cm2

dynes
cm2

X

1
cm/Sec

1

X

1/cm

cm

X 1/

1
X

Sec

cm

η= Dynes cm-2 Sec = Poise “ P ”
1 cp= 10-2 P
Water at 20 °C has a viscosity of 1.0020 cP.

Kinematic viscosity
• In many situations, we are concerned with the ratio of
the inertial force to the viscous force.
• This ratio is characterized by the kinematic viscosity ,
defined as follows:

• Ʋ=

ƞ
ρ

• The SI unit of ν is m2/s. The SI unit of ρ is kg/m3.
• The cgs physical unit for kinematic viscosity is
the stokes
•

(St).

It is sometimes expressed in terms
of centiStokes

(cSt).

1 P= d X Stokes

So, Stokes = P/ d

Stokes = Dynes cm-2 Sec / (g / cm3)
Stokes = g cm Sec-2 .cm-2 Sec / (g / cm3)

Stokes = cm2 / Sec

1 cSt= 10-2 St
1 St = 1 cm2·s−1 = 10−4 m2·s−1.
1 cSt = 1 mm2·s−1 = 10−6m2·s−1.

Water at 20 °C has a k. v. of about 1 cSt.

Cannon-Fenske Routine Viscometer
for Transparent Liquids

Zeitfuchs Cross-Arm Viscometers
for
Transparent
and
Opaque
Liquids

(E) Solubility characteristics:
• The Solubility characteristics of the various hydrocarbons
types play an important part in the extraction processes like
extraction of aromatics which dissolve in polar solvent like
phenol much better than paraffins and naphthenes.
• Although the physical properties of petroleum and petroleum
products are often equated with those of the various related
hydrocarbons, the electrical and optical properties of pure
hydrocarbons have been investigated to a lesser degree
than the so-called typical physical properties, leaving
considerable gaps in knowledge. Thus very little is known
about the electrical and optical properties of crude oil.

(F) Electrical properties:

• The electrical properties of crude oil and
crude oil products (especially lubricating
oils) can be of considerable practical
significance.

• Electrical Conductivity: The electrical
conductivity of hydrocarbons is quite small. It is
generally recognized that hydrocarbons do not
usually have an electrical conductivity larger than
10-18 Ω/cm. Thus it is not surprising that the
electrical conductivity of crude oils or crude oil
fractions (ASTM D-3114, IP 274) is from 10-19
Ω/cm to 10-12 Ω/cm -. Available data indicate that
the observed conductivity is frequently more
dependent on the method of measurement and
the presence of trace impurities than on the
chemical type of the oil. Most oils increase in
conductivity with rising temperatures.

• Dielectric Strength: The dielectric strength, or
breakdown voltage (ASTM D-877; see also IP
295), is the greatest potential gradient or
potential that an insulator can withstand without
permitting an electric discharge. The property is,
in the case of oils as well as other dielectric
materials, somewhat dependent on the method
of measurement, that is, on the length of path
through which the breakdown occurs, the
composition, shape, and condition of the
electrode surfaces, and the duration of the
applied potential difference.

(G) OPTICAL PROPERTIES
• Color: The color test has lesser significance in the preliminary
inspection of the
black feedstock.
• Play an important role in determining the purity and/or the stability of
petroleum products,
• for example, tests for the acid or basic nature of petroleum products by
color titration (ASTM D-974, IP 139, 213, IP 431), the Doctor test for
sulfur species (ASTM D-4952), the color of aviation gasoline (ASTM D2392), the color of petroleum products using a color scale (ASTM D1500, IP 17, IP 196), and the color of petroleum products using the
Saybolt chromometer (ASTM D-156). In fact, the test for the color of
petroleum products (ASTM D-1500) can, if desired, be adapted to heavy
oil and bitumen by applying the test to specifically diluted solution of
heavy oil or bitumen in a colorless solvent such as toluene.

• Refractive Index: The refractive index (ASTM D-1218,
ASTM D-1747) is the ratio of the velocity of light in a
vacuum to the velocity of light in the substance.
• The refractive index can be used to give information
about the composition of hydrocarbon mixtures (ASTM
D-2140, ASTM E-1303, IP 346, IP 391, IP 436). As
with density, low values are typical of paraffins and
higher values are typical of aromatic compounds.
• The method (ASTM D-1218) covers the measurement
of the refractive index of liquid petroleum and
petroleum products in the range of 1.3300-1.6500.
Typically, the measurement is carried out at 20oC
(68°F).

• Optical Activity:
• Petroleum is usually dextrorotatory, that is,
the plane of polarized light is rotated to the
right, but there is known levorotatory crude
oils, that is, the plane of polarized light is
rotated to the left, and some crude oils have
been reported to be optically inactive.
• Optically active crude oils shows that the
rotatory power increases with molecular
weight (or boiling point) to pronounced
maxima and then decreases again.

(2) Chemical Properties of crude oil
It is very difficult to discuss the chemical reaction
in which various hydrocarbons can enter so, only a
few important groups of reactions will be
considered, namely:
Reaction under the influence of heat ( thermal
reactions pyrolysis )
Reaction under the influence of oxygen (
oxidation reactions )

• Thermal reactions:
Thermal stability of
hydrocarbons decreases, in general, as M. wt
increase.
• Oxidation Reaction: Most pure paraffin's naphthenes
and Aromatic are not affected by oxygen under
atmospheric pressure and temp and therefore stable
in storage. It should be mentioned that olefins and
practically di-olefins are easily oxidized and converted
into polymers.
• Many so called " impurities " like nitrogen , oxygen
and Sulphur compounds occurring in relatively small
% in crude oil may give troubles when present in
certain product , especially when the product have
been aged during storage (oxidation).

Classification of Oils
• Classification as a Hydrocarbon Resource

• Classification by Chemical Composition

• To accommodate crude oils that were neither
paraffin base nor naphthene base, the term
intermediate base is applied.

Compatibility of Crude Oils.
• Petroleum fouling:
• Causes, Tools, and Mitigation methods
• With the high price of light crude oils most
refineries are driven to purchase greater quantities
of lower priced opportunity crudes that are
heavier and contain higher concentrations of sulfur
and of naphthenic acids.

• This has led to higher frequency of refinery
fouling, just when incentives for refinery
utilization and for energy conservation are at
their peak.
• Fortunately, the understanding of the causes
and mitigation methods of petroleum fouling
has greatly improved recently through the
development of tools for prediction and for
identification.

• Fouling is defined as the formation
of an unexpected phase that
interferes with processing.
• While the fouling phase is often a
solid, a liquid or it could be an
emulsion.
• Fouling make units need to be shut
down periodically for cleaning.

• Most only consider the maintenance cost of
cleaning. The insulating effect of layers of
foulant on heat exchange surfaces can cost
refineries large amounts of energy without it
being realized.
• foulants reduce the efficiency of fractionators
and reduce the reactivity in catalytic reactors.
Most will conclude that they need not wait for
a large fouling incident to justify a significant
program on fouling mitigation.

• Fouling Mitigation Strategy
• The best strategy to mitigate fouling is to
elucidate the foulant chemistry and to use this
basic knowledge to determine how and where
to eliminate its formation.
• Most Common Causes of refinery fouling
are:
• A. Organic
• B. Inorganic

• A. Organic Fouling during Crude Processing
• All organic fouling in the crude unit is due to
insoluble asphaltenes. There are three modes of
insoluble asphaltenes in crude oils:
• asphaltenes may be insoluble in the crude oil as
purchased (self-incompatible),
• the asphaltenes may precipitate when crude oils are
mixed (incompatible), and
• the asphaltenes may adsorb out of the crude oil onto
metal surfaces (nearly incompatible).

• The Oil Compatibility Model and Crude
Incompatibility
•

The oil compatibility model is a solubility parameter based model that enables one to
predict the compatibility or incompatibility of any mixture of any number of oils. This

is based upon testing the compatibility of the individual oils with different
proportions of a model solvent, such as toluene, and a model nonsolvent, such as nheptane. These tests enable measuring the solubility parameter of the mixture at
which asphaltenes just begin to precipitate. This solubility parameter on a reduced n-

heptane-toluene scale is called the insolubility number, IN. In addition, the tests
measure the solubility parameter of the oil that on a reduced n-heptane-toluene scale
is called the solubility blending number, SBN. An example -shown in Figure- where the
compatibility numbers are measured for the two crudes, Souedie and Forties, with

the minimum two tests each. One test, the heptane dilution test, involves determining
the maximum volume of n-heptane that can be added to a given volume of oilwithout
precipitating asphaltenes. Insoluble asphaltenes are most accurately detected by
observing a drop of the mixture between a glass slide and a cover slip under an

optical microscope at 100 to 200X.

3. TESTS AND LAB
APPARATUS

Sampling:
Crude oil sampling in accordance with the international
sampling standards of ISO 3171, ASTM D 4177, API 8.2, IP
6.2, ASTM D 4057, ASTM D 5854 and ASTM D 5842.

•
•

•
•

•
•

Samples:
1 all-levels sample—a sample obtained by submerging a stoppered
beaker or bottle to a point as near as possible to the draw-off level,
then opening the sampler and raising it at a rate such that it is
approximately three-fourths full as it emerges from the liquid.
2 bottom sample— a spot sample collected from the material at the
bottom of the tank, container, or line at its lowest point.
3 bottom water sample—a spot sample of free water taken from
beneath the petroleum contained in a ship or barge compartment or a
storage tank.
4 composite sample— a blend of spot samples mixed in proportion to
the volumes of material from which the spot samples were obtained.
5 drain sample— a sample obtained from the water draw-off valve on a
storage tank.

6 floating roof sample—a spot sample taken just below the
surface to determine the density of the liquid on which the
roof is floating.
7 flow proportional sample—a sample taken from a pipe
such that the rate of sampling is proportional throughout
the sampling period to the flow rate of the fluid in the pipe.
8 upper sample— a spot sample taken from the middle of
the upper one-third of the tank’s contents (a distance of
one-sixth of the liquid depth below the liquid’s surface).
9 middle sample— a spot sample taken from the middle
tank’s contents (a distance of one-half of the depth of liquid
below the liquid’s surface).
10 lower sample— a spot sample of liquid from the middle
of the lower one-third of the tank’s content (a distance of

Reservoir Surface / Subsurface
Samples
From producing reservoirs, representative fluid
samples can usually be obtained at either
surface or subsurface locations.
surface samples are removed at either the
separator or at the wellhead, with the associated
gas and liquid subsequently recombined in
proportions to represent the actual reservoir fluid.

Subsurface samples are removed from within
the wellbore at actual reservoir conditions using
bottom hole sampling tools and techniques.

Equation of State Modelling

useful to evaluate the
quality of the surface samples
and provide a method of
recombining phases in order to
predict overall phase behavior at
reservoir conditions.

Example 1. A saturated oil reservoir
had an original pressure of 15,168
kPag (2200 psi) at 65°C (149°F). Since
that time the reservoir has been
depleted to a current reservoir
pressure of 11,032 kPag (1600 psig).
In order to perform laboratory tests on
the field it was desired to recombine
separator oil and gas samples to
represent the present in situ liquid
phase.

PVT TESTS
• designed to study and quantify the phase behavior
and properties of a reservoir fluid at simulated
recovery conditions.
• The PVT tests are conducted in the absence of
water.
• The majority of tests are depletion experiments,
where the pressure of the single phase test fluid is
lowered in successive steps either by increasing the
fluid volume or removing part of it.
• The reduction of pressure results in formation of a
second phase, except in dry and wet gas mixtures.

• An important test on all reservoir fluid samples is the
determination of the fluid composition.
• The most common method of compositional analysis of high
pressure fluids is to flash a relatively large volume of the fluid
sample at the atmospheric pressure to form generally two
stabilized phases of gas and liquid.
• The two phases are individually analyzed and then
numerically recombined, using the ratio of the separated
phases. The gas and liquid phases are commonly analyzed
by gas chromatography and distillation, respectively.
• The above analysis approach, known as the "blow-down"
method, can give reliable results for large samples of high
pressure liquids, where the error involved in measurement of
the two phase ratio is relatively small. For small samples or
high pressure gases, where the condensate volume formed
by blow down is low, the technique is unreliable.

CRUDE OIL ANALYSIS
1- ELEMENTAL (ULTIMATE) ANALYSIS
2- Analysis For General Characteristics of
Crude Oil
3- Compositional Analysis:

4. Refinery Distillates Tests

Oil Tank

Desalter

+
Filter

H.Ex.

_

Crude
Oil
Pump

Gases

L.Naphtha
H.Naphtha
Kerosene
Gas Oil
Diesel Oil

Fuel Oil (residue)

Pre
Flash
Tower

Atmospheric Distillation

Tow component mixture is contained in a
vessel.
When heat is add, the more volatile material
( red dotes ) start to vaporize.
The vapor contains
A higher proportion
of red dots than
dose the original
Liquid.

Oil treating requires a knowledge of
emulsions.
water-in-oil emulsion
Oil-in-water emulsion

Water-in-Oil
Emulsion

Oil-in-Water
Emulsion

Separated
Oil & Water

The objective:
Is to separate the oil from the water, or to break
the emulsion.
Generally, the emulsion must be:
 Heated ,and
 Emulsion breaking chemical added

To accomplish this.

VACUUM DISTILLATION
GAS
OIL
LIGHT W. D.

MEDIL W. D.

HEAVY W. D.
Pump

RESIDUAL W. D.

Pump

hydrodesulfurization.

hydrodesulfurization.

Platforming process.

Iso. C4

5. LUBRICATING
OILS TESTS

Lubrication Principles

• 1. Friction
• Friction is a force that resists relative motion
between two surfaces in contact.
• Friction may be desirable (Tire on pavement FOR
braking)or undesirable (operation of engines).
• The energy expended in overcoming friction is
dispersed as heat and is considered to be wasted.
• This waste heat is a major cause of excessive wear
and premature failure of equipment.
• Two general cases of friction occur: sliding friction
and rolling friction.

• A. Sliding friction.
• To visualize sliding friction, imagine a steel block lying on a
steel table. Initially a force F (action) is applied horizontally in
an attempt to move the block. If the applied force F is not
high enough, the block will not move because the friction
between the block and table resists movement. If F is
increased to be sufficient to overcome the frictional
resistance force f and the block will begin to move. At this
precise instant, the applied force F is equal to the
resisting friction force f and is referred to as the force of
friction.
• B. Rolling friction.
• When a body rolls on a surface, the force resisting the motion
is termed rolling friction or rolling resistance.

Experience shows that much less force is required
to roll an object than to slide or drag it.

• 2. Wear
• Wear is defined as the progressive damage
resulting in material loss due to relative contact
between adjacent working parts.
• Although some wear is to be expected during
normal operation of equipment, excessive friction
causes premature wear, and this creates significant
economic costs due to equipment failure, cost for
replacement parts, and downtime. Friction and wear
also generate heat, which represents wasted energy
that is not recoverable.
• In other words, wear is also responsible for overall
loss in system efficiency.

Lubrication and Lubricants
a. Purpose of lubrication.
• The primary purpose of lubrication is to reduce wear
and heat between contacting surfaces in relative
motion.
• While wear and heat cannot be completely
eliminated, they can be reduced to negligible or
acceptable levels.
• Lubrication is also used to reduce oxidation and
prevent rust; to provide insulation in transformer
applications; to transmit mechanical power in
hydraulic fluid power applications; and to seal
against dust, dirt, and water.

BASE OIL
PRODUCTION

Solvent Extraction Process

SOLVENT DEWAXING PROCESS

P.
P.+W.D
W.D.

R.W.D.

L.P. PROPANE
P.
P.+BITUMEN
BITUME

Greases
•Greases = OIL + Thickening AGENT
•Thickening AGENT = Soap of
Na, Al, Ba, Ca, Li, Sr
Or Mixed Soaps

•Soap = Fatty acid + M
•M = Na , Al, Ba, Ca, Li, Sr

Types of Oil

REFINED

• PARAFINIC OIL
• NAPHTHENIC OIL

SYNTHETIC

• MANUFACTURED

• a. Paraffinic oils.
• Paraffinic oils contain paraffin wax and are the most
widely used base stock for lubricating oils. In
comparison with naphthenic oils, paraffinic oils
have:
•
•
•
•
•

! Excellent stability (higher resistance to oxidation).
! Higher pour point.
! Higher viscosity index.
! Low volatility and, consequently, high flash points.
! Low specific gravities.

• b. Naphthenic oils.
• These oils do not contain wax and behave
differently than paraffinic oils. Naphthenic oils have:
•
•
•
•
•

! Good stability.
! Lower pour point due to absence of wax.
! Lower viscosity indexes.
! Higher volatility (lower flash point).
! Higher specific gravities.

• Naphthenic oils are generally reserved for
applications with narrow temperature ranges and
where a low pour point is required.

• c. Synthetic oils.
• Synthetic lubricants are produced from chemical
synthesis rather than from the refinement of existing
petroleum or vegetable oils.
• These oils are generally superior to petroleum
(mineral) lubricants in most circumstances.
• Synthetic oils perform better than mineral oils in the
following respects:
•
•
•
•

! Better oxidation stability or resistance.
! Better viscosity index.
! Much lower pour point, as low as -46 oC (-50 oF).
! Lower coefficient of friction.
DIS ADVANTAGES: HIGH PRICE

• Synthetic lubricant categories.
Several major categories of synthetic lubricants are available including:
• (a) Synthesized hydrocarbons. Polyalphaolefins and dialkylated
benzenes are the most common types. These lubricants provide
performance characteristics closest to mineral oils and are compatible
with them.
• Applications include engine and turbine oils, hydraulic fluids, gear and
bearing oils, and compressor oils.
• (b) Organic esters. Diabasic acid and polyol esters are the most
common types. The properties of these oils are easily enhanced through
additives. Applications include crankcase oils and compressor lubricants.
• (c) Phosphate esters. These oils are suited for fire-resistance
applications.
• (d) Polyglycols. Applications include gears, bearings, and compressors
for hydrocarbon gases.
• (e) Silicones. These oils are chemically inert, nontoxic, fire-resistant,
and water repellant. They also have low pour points and volatility, good
low-temperature fluidity, and good oxidation and thermal stability at high
temperatures.

Lubricant Additives

The SAE classification of oils

• S A E
• Society of Automotive Engineers
• The SAE classifies motor oils according to
certain viscosities and very general
temperature ranges at which they can be
used.
• Automobile and equipment manufacturers
also specify which oil should be used for a
particular ambient temperature operation.

• Today, most automobiles and trucks
use multi-viscosity oils.
• Multi-viscosity petroleum oils are
manufactured by starting with a
lower viscosity base stock oil and
blending in Viscosity Index
Improvers (VI’s).
• The purpose of the VI’s are to allow
a lower viscosity oil, such as a SAE
10W oil to flow like a 10W oil at low
ambient temperatures (such as
during cold starting) and also flow
like a SAE 30W oil at higher ambient
and operating temperatures.
• The resultant formulation is called a
multi-viscosity oil, and in this
example, would be called a
SAE 10W-30.

6. NATURAL GAS

Natural gas is commercially produced from
oil fields
and
natural gas fields
from oil wells is called
from reservoirs that contain
(casing head gas or
only gaseous constituents
associated gas), when
and no (or little) petroleum
it is in solution with
called (unassociated gas).
Petroleum in the
reservoir called
(dissolved gas),
Natural gas is also found in coal beds (as coalbed methane). It
sometimes contains significant quantities of ethane, propane,
butane, and pentane—heavier hydrocarbons removed prior to use
as a consumer fuel—as well as carbon dioxide, nitrogen, helium
and hydrogen sulfide.

Types of natural gas vary according to composition.
There is dry gas or lean gas, which is mostly methane, and
wet gas, which contains considerable amounts of highermolecular-weight and higher-boiling hydrocarbons. Sour gas
contains high proportions of hydrogen sulfide, whereas sweet
gas contains little or no hydrogen sulfide. Residue gas is the
gas remaining (mostly methane) after the higher-molecularweight paraffins have been extracted). Casinghead gas is the
gas derived from an oil well by extraction at the surface.

Natural gas has no distinct odor and its
main use is for fuel, but it can also be used
to make chemicals and liquefied petroleum
gas.

Composition of Associated Natural Gas from a Petroleum Well

0.08

Natural gas processing:

Uses of Natural Gas:
•

•

•
•
•

•
•

Power generation : Natural gas is a major source of electricity generation through
the use of gas turbines and steam turbines. Most grid peaking power plants and
some off-grid engine-generators use natural gas.
Domestic use : Natural gas is supplied to homes, where it is used for such purposes
as cooking in natural gas-powered ranges and/or ovens, natural gas-heated clothes
dryers, heating/cooling and central heating.
Transportation: Compressed natural gas (methane) is a cleaner alternative to other
automobile fuels such as gasoline (petrol) and diesel.
Fertilizer: Natural gas is a major feedstock for the production of ammonia, via the
Haber process, for use in fertilizer production.
Aviation: Recently a development programs are running to produce LNG- and
hydrogen-powered aircraft. It claims that at current market prices, an LNG-powered
aircraft would reduce cost to 60%, with considerable reductions to carbon monoxide,
hydrocarbon and nitrogen oxide emissions. The advantages of liquid methane as a jet
engine fuel are that it has more specific energy than the standard kerosene mixes do
and that its low temperature can help cool the air which the engine compresses for
greater volumetric efficiency, in effect replacing an intercooler. Alternatively, it can be
used to lower the temperature of the exhaust.
Hydrogen: Natural gas can be used to produce hydrogen, with one common method
being the hydrogen reformer.
Other: Natural gas is also used in the manufacture of fabrics, glass, steel, plastics,
paint, and other products.

PROPERTIES AND TEST METHODS
• SAMPLING: (ASTM D-1145, ASTM
D-1247, ASTM D-1265).

• Usually achieved
using stainless steel
cylinders, piston
cylinders (ASTM D3700), glass cylinder
containers or polyvinyl
fluoride (PVF)
sampling bags may
also be used

Calorific Value (Heat of Combustion)
• Various types of test methods are available for the direct determination of
calorific value (ASTM D-900, ASTM D-1826, ASTM D-3588, ASTM D4981). The most important of these are the Wobbe index,
[WI; or Wobbe number = calorific value / (specific gravity)
• and the flame speed, This factor can be calculated from the gas analysis.
• Another important combustion criterion is the gas modulus,
M = P/W,
• where P is the gas pressure and W is the Wobbe number of the gas.
• This must remain constant if a given degree of aeration is to be
maintained in a preaerated burner using air at atmospheric pressure.

Composition

• because of the lower-molecular-weight constituents of
these gases and their volatility, gas chromatography
has been the technique of choice for fixed gas and
hydrocarbon speciation and mass spectrometry is also
a method of choice for compositional analysis of lowmolecular-weight hydrocarbons (ASTM D-2421, ASTM
D-2650). ASTM D-1945 is a test method covers the
determination of the chemical composition of natural
gases and similar gaseous mixtures.
• Once the composition of a mixture has been
determined it is possible to calculate various
properties such as specific gravity, vapor pressure,
calorific value and dew point.

7. SUDAN
CRUDE OIL

Oil in Sudan

• Oil exploration in Sudan was first initiated
in 1959 by Italy’s Agip oil company in
the Red Sea area.
• Several oil companies followed Agip in the
Red Sea Area but none were successful
in their exploration efforts.
• The first oil discovery in Sudan was made
by Chevron in the south of Sudan in
1979, west of the Muglad.

Chevron continued its successful exploration
and made more significant discoveries in the so
called Unity and Heglig fields.
- In 1983 Chevron, Royal Dutch Shell, the
Sudanese government, and the Arab Petroleum
Investments Corporation (Apicorp) formed the
White Nile Petroleum Company in order to build
an oil pipeline from the Sudanese oil fields to Port
Sudan on the Red Sea.
- In 1999 the pipeline became operational and
carried the first Sudanese oil exports to Port
Sudan.

Oil reserves and production:
• Reserves: according to BP statistical
review of world energy 2006, Sudan has a
proved oil reserve of 6.4 thousand million
barrels. The oil exploration has been
limited to the central and south central
regions. It is estimated that the country
holds vast potential reserves in the east,
north-west and south of the country.

• Production:
• In 1999 the construction of an export pipeline,
that connected the Heglig oil fields in central
Sudan to Port Sudan on the Red Sea, was
completed. This led to a considerable increase
in oil production, and the first oil export in the
history of Sudan. Since then production has
increased steadily.
• In April 2006 another 1400 km pipeline, from
Upper Nile in Sudan’s south-east to the eastern
Port Sudan became operational. This pipeline
will raise production to 500,000 b/d in 2006 and
it is estimated that it will double the production in
2007.

Sudan Oil Blocks:
Blocks 1, 2, and 4 (Nile Blend):
Heglig and Unity fields
maximum capacity is 450,000
bbl/d.

Blocks 3 and 7 (Dar Blend):
Adar Yale and Palogue oil fields
maximum capacity is 500,000
bbl/d.
Block 5a:
Thar Jath and Mala fields
maximum capacity is 60,000
bbl/d.
Block 6:
Fula field
maximum capacity is 40,000
bbl/d

• Other Blocks:
• Block B: Block B is located in southeastern Sudan and is licensed to Total.
The company has faced several problems resulting from conflict in the
area, licensing problems, and, more significantly, the existing consortium
continues to seek a third partner to replace Marathon Oil, a U.S. company
that was forced to pull out of its 32.5 percent interest as a result of U.S.
sanctions.
• Block 5B: Block 5B is located in the southern Muglad Basin and was
initially under exploration by ONGC Videsh (23.5 percent stake) and
Lundin (Sweden 24.5 percent) in partnership with Sudapet (13 percent),
and Petronas (39 percent). In early 2009, two major stakeholders, ONGC
and Lundin pulled out after negative drilling results. In August 2009, the
National Petruleum Commision approved the participation of Ascom, a
Moldovan firm in block 5B.
• Block EA: According to the BBC, the NPC recently mapped out a new oil
concession called EA. This block is a long narrow strip that runs along
existing fields in the Muglad Basin.

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