petroleum export

7/29/2019 petroleum export

1/35

Crude oil, Its Formation, Composition, Classification, &Exploration

Speaker: Dr. O.P.Rao


2/35

Crude oil and its Formation

Petroleum or crude oil is a naturally occurring, flammable liquid

found in rock formations in the Earth

It consists of a complex mixture of hydrocarbons (hydrogen and

carbon) of various molecular weights,

The word petroleum comes from the Latinpetra,meaning rock, and

oleum,meaning oil.


3/35

Crude oil is usually either black or green, but it can also be light

yellow or transparent.

Crude oils vary considerably in density and are described as heavy,

average, or light.

Both crude oil and natural gas are formed from ancient dead plant

and animal material that lies buried in layers of sedimentary rock.

The oil and gas then migrates through the pores in the rocks to

eventually collect in reservoirs.


4/35

Petroleum deposits arise from the decomposition of aquatic, mainly marine, animalsand plants successively buried under layers of mud and silt several hundred millionyears ago


5/35

Besides the formation of petroleum is only part of the picture: it must also beeffectively contained

Today, countless million years after they have formed, oil and gas are only foundwhere migration from the original source rock to reservoir rock has occurred as aresult of the high pressures in the source rock, and the hydrocarbon has beentrapped in the reservoir

For this to have happened two general conditions apply.

The first is that furtherupward migration has been prevented by an impermeableseal known ascaprock, and

the second condition is that further lateral migration has been prevented, or greatlyreduced, by the natural occurrence ofgeological traps (structural trap)within the

reservoir beds themselves.


6/35

Structural Traps are three types:anticline, fault trap and salt dome


7/35

Anticlinal: Sloping downward in opposite directions

the anticline which is the most common, accounting for around 80% of the worlds oil

and gas resourcesAnticlines are formed by folds in the earths geological strata and when occurring in

large structures can hold appreciable quantities of petroleum in place


8/35

A fault trap is formed when a bed of reservoir rock is brought into contact withimpermeable strata by movement along a geological fault within the earths

crust

Fault trap


9/35

Salt dome, as the name suggests, is a dome-shaped formation of rock saltwhich has been forced upwards through overlying strata until it lies undercaprock

Salt Dome


10/35

The following conditions must be present for oil reservoirs to form:

A source rock rich in hydrocarbon material buried deep enough forsubterranean (beneath the earth's surface) heat to cook it into oil;

Lateral movement of hydrocarbon deposits

A porous and permeable reservoir rock for it to accumulate in;

And a cap rock (seal) that prevents it from escaping to the surface.

Within these reservoirs, fluids will typically organize themselves like

a three-layer cake with a layer of water below the oil layer and a

layer of gas above it,


11/35

Crude oils from different parts of the world, or even from different

depths in the same oilfield, contain different mixtures of

hydrocarbons and other compounds.

This is why they vary from light coloured volatile liquids to thick, dark

oils.

In its strictest sense, petroleum includes only crude oil, but in

common usage it includes both crude oil and natural gas.

An oil well produces predominantly crude oil, with some natural gas

dissolved in it recovered as associated gas

A gas well produces predominately natural gas.


12/35

Theproportion of hydrocarbons in the petroleum mixture is highly

variable between different oil fields

Composition by weight of Crude Oil

Carbon -83 to 87%, Hydrogen- 10 to 14%, Nitrogen- 0.1 to 2%,

Oxygen- 0.1 to 1.5%, Sulfur-0.5 to 6%, Metals- less than 1000 ppm


13/35

Classification

Crude oils are generally classified as paraffinic, naphthenic, or

aromatic, based on the predominant proportion of similarhydrocarbon molecules.

Hydrocarbon Average Range

Paraffins 30% 15 to 60%

Naphthenes 49% 30 to 60%

Aromatics 15% 3 to 30%

Others 6% remainder
http://en.wikipedia.org/wiki/Paraffinhttp://en.wikipedia.org/wiki/Naphthenehttp://en.wikipedia.org/wiki/Aromatichttp://en.wikipedia.org/wiki/Aromatichttp://en.wikipedia.org/wiki/Naphthenehttp://en.wikipedia.org/wiki/Paraffin


14/35

Paraffins

General formula: CnH

2n+2(n is a whole number, usually from 1 to 20)

Can be gasses or liquids at room temperature depending upon themolecule

Examples: methane, ethane, propane, butane, isobutane, pentane,

hexane, octane (methane, CH4 , ethane, C2H6 , propane, C3H8 , butane, C4H10 ,pentane, C5H12 ,hexane, C6H14

The simplest paraffin molecule is that of methane, CH4, a gas at room

temperature.

Heavier members of the series, such as that of octane C8H18, appearas liquids at room temperature.

The solid forms of paraffin, calledparaffin wax, are from the heaviest

molecules from C20H42 to C40H82.
http://en.wikipedia.org/wiki/Ethanehttp://en.wikipedia.org/wiki/Propanehttp://en.wikipedia.org/wiki/Butanehttp://en.wikipedia.org/wiki/Pentanehttp://en.wikipedia.org/wiki/Hexanehttp://en.wikipedia.org/wiki/Hexanehttp://en.wikipedia.org/wiki/Pentanehttp://en.wikipedia.org/wiki/Butanehttp://en.wikipedia.org/wiki/Propanehttp://en.wikipedia.org/wiki/Ethane


15/35

Aromatics

General formula: benzene ring (C6H6)

Examples: benzene, toluene ,napthalene

Benzene and toluene, have distinctive pleasant smells, hence

the term "aromatic

Napthenes orCycloalkanesGeneral formula: CnH2n

Typically liquids at room temperature

Examples: cyclohexane,(C6 H12) methyl cyclopentane

(C5

H9

CH3

)


16/35

Other hydrocarbons

Alkenes

General formula: CnH2n (n is a whole number, usually from 1 to 20)

Can be liquid or gas

Examples: ethylene, butene, isobutene

AlkynesGeneral formula: CnH2n-2

Can be liquid or gas

Examples: acetylene (C2H2), butadienes


17/35

The petroleum industry generally classifies crude oil by the

geographic location it is produced (West Texas Intermediate, Brent,or Oman)

Crude oil is also classified by its API gravity (an oil industry

measure of density), and

by its sulfur content.


18/35

American Petroleum Institute gravity (API gravity)

It is a measure of how heavy or light a petroleum liquid is comparedto water.

If its API gravity is greater than 10, it is lighter and floats on water;

If less than 10, it is heavier and sinks.

API gravity is graduated in degrees on a hydrometer instrument and

most values fall between 10 and 70 API gravity degrees.

Generally speaking, oil with an API gravity between 40 and 45

commands the highest prices.


19/35

Crude oil is classified as light, medium or heavy, according to its

measured API gravity.

Light crude oil is defined as having an API gravity higher than 31.1

API

Medium oil is defined as having an API gravity between 22.3 APIand 31.1 API

Heavy oil is defined as having an API gravity below 22.3 API.


20/35

It may be referred to as sweet if it contains relatively little sulfur

(0.5%) or sourif it contains substantial amounts of sulfur (>0.5%)

The term "sweet" originated because the low level of sulfur

provides the oil with a mildly sweet taste and pleasant smell.

Light sweet crude oil" is the most sought-after version of crudeoil as it can be processed to yield gasoline, kerosene, and high-

quality diesel


21/35

DegreeAPI

SpecificGravity

Weight

(lb/US gal) (kg/m3)

8 1.014 8.448 1012

9 1.007 8.388 100510 1.000 8.328 998

15 0.966 8.044 964

20 0.934 7.778 932

25 0.904 7.529 902

30 0.876 7.296 874

35 0.850 7.076 848

40 0.825 6.870 823

45 0.802 6.675 800

50 0.780 6.490 778

55 0.759 6.316 757

58 0.747 6.216 745

API gravity express the gravity or density of liquid petroleum products

The formula for API Gravity can be expressed as:API = (141.5 / SG) - 131.5whereAPI = Degrees API Gravity

SG = Specific Gravity (at 60o

F)


22/35

Brent crude is one of the most important benchmark crude oils.

Two thirds of the world's internationally traded crude oil suppliesare priced relative to it.

The benchmark oil is a combination of crude oil from 15different oil fields in the Brent and Ninian areas of the North

Sea.

Petroleum production from Europe Africa and the Middle Eastflowing West tends to be priced relative to this oil, i.e. it forms a

benchmark

The API gravity of Brent is 38.3 degrees and it contains littlesulphur making it a light sweet crude oil.


23/35

Petroleum ExplorationVisible surface features such as oil seeps, natural gas seeps,pockmarks (craters caused by escaping gas) provide basic evidence of

hydrocarbon generation

Exploration surveys adopted are: gravity survey, magnetic survey,seismic reflection surveys

An exploration well is drilled in an attempt to conclusively determinethe presence of oil or gas


24/35

Oil extraction and recoveryOil is extracted as Primary Recovery, Secondary recovery and Tertiaryrecovery (enhanced recovery)

Primary RecoveryPrimary production is the first method of producing oil from a well anddepends on the natural reservoir energy to drive oil into producingwells

These include: natural water displacing oil upward into the productionwell,


25/35

Expansion of the natural gas dissolved in the crude oil,

And gravity drainage resulting from the movement of oil within thereservoir from the upper to the lower parts where the wells are located.

The underground pressure in the oil reservoir is sufficient to force the oil tothe surface through an arrangement of valves

Pumping arrangement is not required

Recovery factor during the primary recovery stage is typically less than 15-20%


26/35

Secondary & Tertiary RecoveryAt some point there will be insufficient underground pressure to force theoil to the surface

After natural reservoir drive diminishes, secondary recoverymethods are applied.

They rely on the supply of external energy into the reservoir to produce

more oil.

Most common secondary recovery operations consist of pumpingoperations and injection of material into well

Injection of water or gas called water flood or gas flood

The pumps are reciprocating type


27/35

Separate wells are used for injection and production

Steam injection is used to reduce the viscosity of crude oil so that it easilyflows into the production well

A gas is injected into the oil-bearing stratum under high pressure.

That pressure pushes the oil into the pipe and up to the surface.

In addition to the beneficial effect of the pressure, this method sometimesaids recovery by reducing the viscosity of the crude oil as the gas mixeswith it.

Gases commonly used include CO2, natural gas or nitrogen.


28/35


29/35

Enhanced oil recovery by injection of CO2 and steam
http://en.wikipedia.org/wiki/File:The_extraction_of_Oil_using_steam.jpg


30/35

DrillingThe well is created by drilling a hole 5 to 36 inches (127.0 mm to 914.4

mm) diameter into the earth with a drilling rig

After the hole is drilled, sections of steel pipe (casing), slightly smaller indiameter than the borehole, are placed in the hole.

Cement may be placed between the outside of the casing and theborehole.

The casing provides structural integrity to the newly drilled wellbore


31/35

The 2006 cost of a Central North Sea high pressure, high temperaturewell is about $3550 million.

Deep water wells in the Gulf of Mexico can cost over $100 million.

Onshore wells can be considerably cheaper, particularly if the field is at ashallow depth, where costs range from less than $1 million to $15 million

for deep and difficult wells


32/35


33/35

Crude oil can also be obtained from oil shales and tar sands

(Unconventional oils)

Oil shale, an organic-rich fine-grained sedimentary rock, contains

significant amounts of kerogen (a solid mixture of organic chemical

compounds) from which liquid hydrocarbons are extracted)

Estimates of oil shale global deposits range from 2.8 trillion to3.3 trillion barrels

The chemical process of pyrolysis can convert the kerogen in oil

shale into synthetic crude oil


34/35

Most of the world's oils are non-conventional
http://en.wikipedia.org/wiki/File:Total_World_Oil_Reserves.PNG


35/35

Oil sands, also known as tar sands, or extra heavy oil, is an

extremely dense and viscous form of petroleum called bitumen

Heavy crude oil is closely related to oil sands, the main difference

being that oil sands generally do not flow at all

Heavy crude oil or Extra Heavy Crude oil is any type of crude oilwhich does not flow easily.

It is referred to as "heavy" because its specific gravity is higher than

that of light crude oil.

Date post:	04-Apr-2018
Category:	Documents
Upload:	jasjit-singh
View:	222 times
Download:	0 times

petroleum export

Documents