Petroleum Geology - Copy

8/13/2019 Petroleum Geology - Copy

1/63

LOGO

Petroleum Geology

Reservoir rock properties coursePeyman Maroufi

Petroleum Geoscience department

Soran university


2/63

What is petroleum

What is petroleum

Petroleum is a mixture of naturally occurring hydrocarbons whichmay exist in the solid, liquid, or gaseous states, depending upon the

conditions of pressure and temperature to which it is subjected.

Whereas natural gas contains a few lighter hydrocarbons, both crudeoil and tar deposits may consist of a large number of different

hydrocarbons.

1) Liquid Hydrocarbons: Crude oil or Petroleum

2) Gas Hydrocarbons: Natural Gas: methane,

butane, propane, etc.

3) Solid Hydrocarbons: Tars and Asphalt


3/63

What is petroleum

Virtually all petroleum is produced from the earth in either liquid or gaseous form,

and commonly, these materials are referred to as either crude oil or natural gas,

depending upon the state of the hydrocarbon mixture.

Petroleum consists chemically of approximately 11 to 13 wt % hydrogen and 84 to

87 wt % carbon.

Traces of Oxygen, Sulfur, Nitrogen, and Heliummay be found as impurities in crudepetroleum.

Although all petroleum is constituted primarily of carbon and hydrogen, the

molecular constitution of crude oils differs widely.


4/63

Chemistry of Petroleum

Hydrocarbons:

In organic chemistry, a hydrocarbon is an organic

compound consisting entirely of hydrogenand carbon

atoms.

The simplest

hydrocarbon isMethane (CH4)

The classifications for hydrocarbons:

1) Saturated hydrocarbons (alkanes)

2) Unsaturated hydrocarbons

3) Cycloalkanes4) Aromatic hydrocarbons


5/63


1) Saturated hydrocarbons (alkanes):

Saturated hydrocarbons (alkanes) are the simplest of the hydrocarbon speciesand are composed entirely of single bonds and are saturated with hydrogen.

The general formula for saturated hydrocarbons is:


6/63


1) Saturated hydrocarbons (alkanes):

Saturated hydrocarbons are the basis of petroleum fuels andare found as either linear or branched species.

These alkane also are calledparaffin hydrocarbons.

Petroleum engineer normally call theseparaffins.


7/63


2) Unsaturated hydrocarbons:

Unsaturated hydrocarbons have one or more double or triple bondsbetween carbon atoms.

A) alkenes:

The distinguishing feature of the alkene structure is thecarbon-carbon double bond.

The general formula for the alkene family is:


8/63


A) alkenes:


9/63


B) alkynesThose containing triple bonds are called alkynes, with general formula

2) Unsaturated hydrocarbons:

Unsaturated hydrocarbons have one or more double or triple bondsbetween carbon atoms.


10/63


3) Cycloalkanes

Cycloalkanesare hydrocarbons containing one or more carbon rings to

which hydrogen atoms are attached.

The general formula for a saturated hydrocarbon containing one ring is:


11/63


The cycloalkanes also are known asNaphthenes, Cycloparaffins, or

alicyclichydrocarbons.

In the petroleum industry, this class of hydrocarbons is known as

Naphthenes. Naphthenes have saturated rings.

3) Cycloalkanes


12/63


4) Aromatic hydrocarbons:Aromatic compounds (also called arenes) include benzene

and compounds that resemble benzene in chemical behavior.

Benzene:Benzene, C6H6, is the simplest aromatic hydrocarbon and was recognized as the

first aromatic hydrocarbon


13/63


14/63

Non hydrocarbon Components of Petroleum

Petroleum also contain compounds:

1) Sulfur Compounds.

2) Nitrogen

3) Oxygen

4) Little metals

Common non hydrocarbon constituents of petroleum

are:

1) Nitrogen ()2) carbon dioxide ()

3) hydrogen sulfide ()


15/63


Resins and Asphaltenes

The chemicals in petroleum are classified as:

1) Paraffins

2) Naphthenes

3) Aromatics

4) Resins-asphaltenes

Resins and asphaltenes are large molecules, primarily hydrogen and carbon,

with one to three sulfur, oxygen, or nitrogen atoms per molecule.

The basic structure is composed of rings, primarily aromatic, with from three to

ten or more rings in each molecule. The non hydrocarbon atom can be a part ofthe ring structure or can be located in links connecting the rings.

The color of petroleum is determined largely by the quantity of resinsand

asphaltenespresent, although the greenishcast of some crude oils is probably

due to the presence of molecules containing six or more rings.


16/63


The exact molecular composition varies widely from formation to formation

but the proportion of chemical elementsvary over fairly narrow limits as

follows:


17/63

Composition of petroleum

Average and Range of Hydrocarbon series molecules in Crude Oil


18/63



19/63



20/63

Origin of petroleum

The theories of the origin of petroleum may be classified as:

1) Organic

2) Inorganic


21/63

Origin of petroleum

Origin of petroleum:

1) Organic theories:

The organic theories assume that petroleum evolved fromdecomposition of vegetable and animal organisms that lived during

previous ages.

2) Inorganic theories:The inorganic theories attempt to explain the formation of petroleum by

assuming chemical reaction among water, carbondioxideand various

inorganicsubstances such as carbides and carbonates, in the earth.


22/63


23/63

Origin of petroleum


24/63

The Origin and Habitat of Petroleum

Accumulation of Oil and Gas

The accumulation of economic volumes of petroleum (oil and/or gas) in the

subsurface requires that several essential geological elements and processes

be present at specific time and space.

The essential elements of a petroleum system include the following:

1) Source rock

2) Reservoir rock

3) Migration

4) Traps


25/63


To have a petroleum accumulation it is necessary to have source rock and a

reservoir or storage bed

Source rock:

Source rocks generate and expel petroleum when sufficient thermal energy is

imparted to the sedimentary organic matter (kerogen) to break chemical bonds.

This heating is induced usually by burial by overburden rock.

Reservoir rock:

A subsurface body of rock having sufficient porosity and permeability to store and

transmit fluids.

A suitable reservoir rock is porous and permeable. That is , the pores interconnect

so that fluids can migrate through the rock.

Sedimentary rocks are the most common reservoir rocks because they have more

porosity than most igneous and metamorphic rocks and


26/63


Migration of petroleum :

The movement of hydrocarbons from their source into reservoir rocks.

1) Primary migration

2) Secondary migration


27/63


1) Primary migration:

The movement of newly generated hydrocarbons out of their source rock is

primary migration, also called expulsion.

2) Secondary migration:

The further movement of the hydrocarbons into reservoir rock in a

hydrocarbon trap or other area of accumulation is secondary migration.


28/63


29/63


30/63

Traps

As oil and gas are lighter than the ground water which permeates the porous rocks

below the water table, it is evident that the upward movement of petroleum must be

restricted in order that accumulations exist at depth


31/63


32/63

Traps

Classification of Hydrocarbon Traps

1) Structural traps :Structural traps are traps that are formed because ofa deformation in the rock layer that contains the hydrocarbons.

a) Anticlinal traps: an upward fold in the layers of rock

b) Fault traps: A fault trap occurs when the formations on either side ofthe fault have been moved into a position that prevents furthermigration of petroleum.

c) diapiric traps: produced by intrusion of salt or mud diapirs

2) Stratigraphic traps: result when a depositional bed changes frompermeable rock into fine-grain impermeable rock


33/63

Traps


34/63

Traps


35/63


GENERATION, MIGRATION, AND

TRAPPING OF HYDROCARBONS


36/63

Types of Rocks

Igneous Rocks about 20% of all rocks they are the product of the cooling of molten magma

intruding from below the mantle of the crust.

Metamorphic rocks about 14% of all rocks originate from mechanical, thermal, and chemicalchanges of igneous rocks

Sedimentary Rocks

about 66% of all rocks they are important to the study of petrophysics andpetroleum reservoir engineering.


37/63

Sediments and Sedimentary Rocks

What are sediments?

Sediment- loose, solid particles originating from:

Weathering and erosion of pre-existing rocks Chemical precipitation from solution, including secretion by

organisms in water


38/63


What is a Sedimentary Rock?

Sedimentary rocksare types of rockthat Sediments after they

are deposited may be buried and undergo physical andchemical change resulting in a solid rock.


39/63


The three most common sedimentary rocks associated

with petroleum reservoirs are:

1) sandstone

2) shale

3) limestone.


40/63

Sedimentary Rock Types

Siltstone, mudand shale

~75%

Relative abundance

Sandstone

and conglomerate~11%

Limestone and

dolomite~13%


41/63


42/63

Dimension and Units

Dimension: A dimension is the measure by which a

physical variable is expressed quantitatively.

Unit: A unit is a particular way of attaching a number

to the quantitative dimension.

For example: length is a dimension associated with

such variables as distance, displacement, width,

deflection, and height, while centimeters and inchesare both numerical units for expressing length


43/63

Dimension and Units

Dimensions:

1) primary dimensions

2) secondary dimensions

primary dimensions :

In fluid mechanics there are only fourprimary dimensions fromwhich all other dimensions can be derived: mass, length, time,

and temperature.

Dimension of mass = [M]

Dimension of length= [L]

Dimension of time = [T]


44/63

Dimension and Units

secondary dimensions:

A secondary dimension is one that is formed by combining

primary dimensions. For example:

Dimension of length:

force,: which is directly related to mass, length, and time by Newtons second law


45/63

Dimension and Units

Systems of Units

Systems of units have always varied widely from country to country, even

after international agreements have been reached.

British Gravitational (BG) System:

In the BG system:

unit of length is: foot (ft) time unit is: second (s)

The mass unit: slug

force unit is: pound (lb)

temperature unit is: degree Fahrenheit (F)

or

absolute temperature unit is: degree Rankine (R) R + 459.67


46/63

Dimension and Units

Newtons second law:

1 (1 ) (1

)

This relationship indicates that a 1-lb force acting on a mass of 1 slug will

give the mass an acceleration of 1

The weight, W (which is the force due to gravity, g) of a mass, m, is given by

the equation:

() () (

)

Since the earths standard gravity is taken as: commonly approximated as

32.174

32.2


47/63

Dimension and Units

International System (SI).

unit of length is: meter (m)

time unit is: second (s)

The mass unit: kilogram (kg)

force unit is: newton (N)

temperature unit is: kelvin degree (K)

The Kelvin temperature scale is an absolute scale and is related to the Celsius

(centigrade) scale (C) through the relationship:

K + 273.15


48/63

Dimension and Units

The force unit, called the newton (N), is defined from Newtons second law as

1 (1 ) (1

)

Standard gravity in SI is:

9.807

9.81


49/63

Dimension and Units

Prefixes for forming multiples and fractions of SI units


50/63


51/63


52/63

Dimension and Units


53/63

Dimension and Units


54/63

Physical properties of Hydrocarbons

Viscosity

Density

Spesific gravity

API

Ph i l i f H d b


55/63


Density:

Density is an extremely important property of matter.

The density of a fluid (or any other form of matter) is the amount of mass

per unit volume.

Dimensions:

Units:

;

;

Density is highly variable in gases and increases nearly proportionally to the

pressure level. Density in liquids is nearly constant. at C and atm:

Water: 1000 kg/m3;

Mercury: 13546 kg/m3;

Air: 1.23 kg/m3;

Paraffin: 800 kg/m3.

Ph i l ti f H d b


56/63


Specific gravity:

Specific gravity, denoted by SG.

Specific gravity is defined as the ratio of the density of a fluid to the density of some

standard fluid at a specified temperature and pressure.

Commonly standard fluid for liquids is Waterand for gasses is Air.

Specific gravity for gases

Specific gravity for liquids

Ph i l ti f H d b


57/63


Specific gravity of gases:

P=14.7 psi = 101.325 kPa =1atm

atT= 60 F = 15 F = 288.15 K

1.225 0.076

0.076



58/63


Specific gravity of Crude Oil:

P=14.7 psi = 101.325 kPa =1atmat

T= 60 F = 15 F = 288.15 K

999 62.4

62.4

The specific gravity of crude oils ranges from

about 0.75 to 1.01.



59/63


The American Petroleum Institute gravity, orAPI gravity

Although the density and specific gravity are used extensively in the petroleum

industry, the APIgravity is the preferred gravity scale. This gravity scale is precisely related to the specific gravity by the following

expression:

141.5

131.5

Conversely, 141.5

+ 131.5


60/63

Crude Oils


61/63

Crude Oils

Light Crude

Palo Pinto FieldNorth Texas

Light Crude

Palo Pinto FieldNorth Texas

Heavy Crude

Humble Oil FieldSouthwest Texas

Heavy Crude

Humble Oil FieldSouthwest Texas



62/63


Viscosity:

The viscosity of a fluid is a measure of the internal fluid friction (resistance) to

flow.

If the friction between layers of the fluid is small, i.e., low viscosity, an applied

shearing force will result in a large velocity gradient.

As the viscosity increases, each fluid layer exerts a larger frictional drag on the

adjacent layers and velocity gradient decreases.

Symbols: o, g, wUnits: cp

Range and typical values

0.25 to 10,000 cp, Black oil

0.5 to 1.0 cp, Water

0.012 to 0.035 cp, Gas



63/63


Petroleum Geology - Copy

Documents

Transcript of Petroleum Geology - Copy