basic intro for properties of crude oil

1. Properties of Crude Oil
By
Syed Nawaz
Delta Studies Institute
Andhra University

2. Content
• Introduction
• Properties
• Reference

3. Introduction
• Crude oil is a complex mixture consisting predominantly of HC and
certain impurities such as sulfur, nitrogen, oxygen and other minor
constituents
• The physical and chemical properties of crude oil vary considerably
and are directly or indirectly rely on the PVT, quantity and quality of
HC, etc.,

4. Properties
• Density
• Specific Gravity
• API
• Gas Solubility
• Oil formation factor and Total Oil Formation factor
• Isothermal compressibility coefficient
• Total and Effective Compressibility
• Crude oil Density
• Viscosity
• Bubble point pressure
• Refractive Index
• Fluorescence
• Calorific value
• Flash point and Burning point
• Cloud and Pour point
• Color, Odor, Optical Density, Surface Tension, Interfacial Tension, Capillarity, Adsorption, Wettability

5. Density, Specific Gravity, API, Bauma
• The density of crude oil is defined as its mass per unit volume of the
crude at a specified pressure and temperature.
• The specific gravity of crude oil is defined as the ratio of the density
over the density of the water, both measured at the same reference
temperature and pressure.
• API gravity of a crude oil is a measure of how heavy or light a crude oil
is compared to water
• API and Density are inversely proportional to each other

7. Gas Solubility
• The gas solubility Rs is defined as ratio of the number of standard
cubic feet of gas that will dissolve in one stock barrel of crude oil
when both oil and gas subjected to the elevated pressure and
temperature conditions encountered in the subsurface formation
• Rs=
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑔𝑎𝑠 𝑒𝑣𝑜𝑙𝑣𝑒𝑑 𝑓𝑟𝑜𝑚 𝑜𝑖𝑙 𝑖𝑛 𝑠𝑐𝑓
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑝𝑟𝑜𝑑𝑢𝑐𝑒𝑑 𝑜𝑖𝑙 𝑓𝑜𝑙𝑙𝑜𝑤𝑖𝑛𝑔 𝑔𝑎𝑠 𝑒𝑣𝑜𝑙𝑢𝑡𝑖𝑜𝑛 𝑖𝑛 𝑠𝑡𝑏

8. Oil Formation Volume Factor
• The Oil formation volume factor, Bo, is a measure of the shrinkage or
reduction in the volume of crude oil as it is produced. Thus it is
defined as the ratio of the volume of oil + the volume of dissolved gas
under reservoir pressure and temperature over the volume of dead
oil at the surface conditions.
• Bo=
𝑉𝑜 𝑟𝑒𝑠
𝑉𝑜 𝑠𝑐

9. Total Formation Volume Factor
• The total formation volume factor is defined as the ratio of the total
volume of the hydrocarbon mixture at the prevailing pressure and
temperature per unit volume of the stock tank oil.
• Bt=
𝑉𝑜 𝑟𝑒𝑠+ 𝑉𝑔 𝑟𝑒𝑠
(𝑉𝑜)𝑠𝑐

10. Isothermal Oil Compressibility
• Oil compressibility is defined as a function of the rate of change in the
volume of crude oil per unit change in pressure at isothermal
condition.
• Compressibility can also be defined as the rate of change in oil density
or formation volume factor per unit change in pressure.

11. Total and Effective Compressibility
• The total compressibility of the system takes into account the
compressibilities of all fluids present in the system, + the
compressibility of rock.
• Effective compressibility of a particular fluid phase is obtained by
dividing the total compressibility by the saturation of that phase in
the porous media.

12. Crude Oil Viscosity
• The viscosity is defined as the internal resistance of the fluid to flow.
• According to pressure, the viscosity of crude oil can be classified into
3 categories:
• Dead Oil Viscosity: the dead oil viscosity id defined as the viscosity of crude oil
at atmospheric pressure and system temperature.
• Saturated Oil Viscosity: the saturated oil viscosity is defined as the viscosity of
the crude oil at the bubble point pressure and reservoir temperature.
• Undersaturated Oil Viscosity: the undersaturated oil viscosity is defined as the
viscosity of the crude oil at a pressure above the bubble- point and reservoir
temperature.

13. Bubble point pressure
• The bubble point pressure of a hydrocarbon system is defined as the
highest pressure at which a bubble of gas is first liberated from the oil
or the pressure above which the fluid essentially remains in a liquid
phase and all of the volatile components are dissolved in the liquid.
• The bubble point pressure of a liquid phase is also referred to as the
saturation pressure since the liquid is completely saturated with
dissolved gas.

14. Refractive Index
• The index of refraction, or refractive index, is a measure of how fast
light rays travel through a given medium. Alternatively, it could be
said that the refractive index is the measure of the bending of a light
ray when passing from one medium to another.
• The range of RI for petroleum is from 1.39-1.49.

15. Flourescence
• Is also called as bloom
• The fluorescent colors of crude oils range continuously from yellow -
green – blue
• Under ultra violet radiation, the petroleum having wavelength of
2537-3650 angstrom unit

16. Calorific Value
• Calorific value is determined by measuring the heat produced by the
complete combustion of a specified quantity
• Units are joules per kilogram
• The calorific value of crude oil decreases as the specific gravity
increases

17. Flash Point and Burning Point
• The flash point is the temperature at which the vapors rising off the
surface of the heated oil will ignite with a flash of very short duration
when a flame is passed over the surface.
• The lowest temperature at which this will occur is known as the
burning point
• Their limits are fixed by state government agency

18. Cloud and Pour Point
• Cloud point is the temperature below which wax in diesel forms a
cloudy appearance and waxes thickens the oils
• Pour point is the minimum temperature at which a lubricants turns
into semi solid and almost losses its flow characteristics

19. Interfacial Tension
• When more than one immiscible fluid phase is present in the porous
medium a thin film develops at the boundary between the 2 fluid
surface.
• At the interface of the fluids, the force exerted by 2 immiscible fluid is
dissimilar, leading to the phenomenon of interfacial tension.
• This results in resisting miscibility between the 2 fluids which
generates a certain resistance to fluid flow in a porous medium.

20. Surface Tension
• It is defined as the force exerted on the boundary layer between a
liquid phase and a vapor phase per unit length.
• The Surface and Interfacial tension has the same units.

21. Wettability
• Wettability is the tendency of one fluid to spread on solid surface in
the presence of other immiscible fluid.
• It depends on the type of minerals in the rock matrix and on the
composition of fluids of the rock.

22. Capillary Pressure
• When 2 immiscible fluid phases such as oil and water, are present in a
porous medium, one of the phase preferentially wets the pore
surface over the other.
• As a result, a pressure differential is found to exist between the 2
phases that can be expressed as capillary pressure
• Pressure exerted by non wetting phase is greater than wetting phase
pressure.

23. Reference
• Syed Nawaz (Ex-NDT Inspector and Ex-Student of PetroGate Academy,
Dehradun, student of Andhra University, India)
• L.P.Dake
• Tarek Ahmed
• A.I.Leverson
• Petrowiki google
• Youtube

24. ?
Any Queries
Mail address: nawaz.delta.au@gmail.com