Oil And Gas Analysis 2en4e

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 s 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 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 = 10-2 P Water at 20 °C has a viscosity of 1.0020 .

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 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 . • 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 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 ing 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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