Where d – density, W – weight of the sample, V – volume of the sample.

• Relative density is calculated by equation

d2020 = ds/dw

where ds - density of the sample at the temperature 20°C, dw - density of water at the temperature 20°C (0.99821 g/cm3)

l Methods of measurements will be used in labs (Hydrometer and pycnometer methods)

• The API (American Petroleum Institute) gravity is another way to express the relative masses of crude oils. The API gravity could be calculated mathematically using the following equation:

oAPI = 141.5/d -131.5

ü A low API gravity indicates a heavier crude oil or a petroleum product, while a higher API gravity means a lighter crude or product. Specific gravities of crude oils roughly range from 0.82 for lighter crudes to over 1.0 for heavier crudes (41 - 10 °API scale).

• 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 °API and 31.1 °API

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

• Oil which will not flow at normal temperatures or without dilution is named bitumen and the API gravity is generally less than 10 °API.

• Light Oils have light products if the boiling of fraction ends under 3500 – gasoline and kerosene

• Heavy Oils have heavy products if the boiling of fraction ends above 3500 –heavy oils, asphaltenes, pitches

• Tengiz Oil

• 46,5 - 47 - density  API (0,79)

• 0,45 - 0,55 – sulfur contain,%

• 7,931 - 7,954 - bbl per ton

• Kumkol Oil

• 40 - 41 - density  API (0,82)

• 0,1 - 0,2 - sulfur contain, %

• 7,641 - 7,686 - bbl per ton

• Mangyshlak oil: low-S (0.2-0.3%), high paraffin (12-26%)

• Tengiz oil: light (0.8 g/cm3) but high sour sulphur content, suitable for refining as fuel.

• Kumkol oil: light (0.835 g/cm3), high in paraffin content(12-16%)

• Karazhanbas oil: high viscosity (10 times greter than Mangyshlak oil).

Viscosity

• Characterize liquids and gases fluidity at engine operation

• Influence on transport, filtration and mixing

• Depends of chemical composition, and international forces

• The heavy oil fractions have more large viscosity than light oil fractions because of molecular mass

• Dynamic Viscosity (or absolute viscosity)– viscosity is the quantity that describes a fluid's resistance to flow.

• Fluids resist the relative motion of immersed objects through them as well as to the motion of layers with differing velocities within them.

• The SI unit of viscosity is the pascal second [Pa·s]

• The most common unit of viscosity is the dyne second per square centimeter [dyne·s/cm2],

•  which is given the name poise [P] after the French physiologist Jean Louis Poiseuille (1799-1869).

• Ten poise is equal one pascal second [Pa·s] making the centipoise [cP] and millipascal second [mPa·s] identical.

1 pascal second =10 poise =

Millipascal second

1 centipoise =1 millipascal second

• Kinematic viscosity n is the ratio of the absolute viscosity to the density.

•  

• n = m/ r

             

• m - absolute viscosity, kg/(m· s);

•  d - density, kg/ m3.

• The SI unit of kinematic viscosity - [m2/s]

• A more common unit of kinematic viscosity is the square centimeter per second [cm2/s], which is given the name stokes [St] after the Irish mathematician and physicist George Gabriel Stokes (1819-1903).

• the most common unit is the square millimeter per second [mm2/s] or centistokes [cSt].

• 1 m2/s = 10,000 cm2/s [stokes] = 1,000,000 mm2/s [centistokes]
1 cm2/s = 1 stokes
1 mm2/s = 1 centistokes

• The viscosity of gasoline at 20°С is about 0,6 mm2/s,

• for heavy residue oil - about 300—400 mm2/s.

• Naphtenes - most viscosity

• Arenas  - medium state

• Paraffines - less viscosity

Specific viscosity

• The ratio of absolute viscosity of oil or oil products to the absolute viscosity of water at the same conditions

• m water= 1 centipoise  at  Т=20,2⁰С

Conditional Viscosity

• The ratio of outflow time of 200 ml of oil sample from viscosimeter under experimental conditions to outflow time of 200 ml of distilled water at 200С

• Defined in   (⁰ CV) units

•    n t = 0,0731 × CVt  - 0,0631/ CVt

• Where n t - kinematics viscosity

• CVt – conditional viscosity at the same T

• Viscosity index

• An arbitrary scale for lubricating oils that indicates the extent of variation in viscosity with variation of temperature.

• VI  is a commonly used method of measuring a fluid's change of viscosity in relation to temperature.

• The higher the VI, the smaller the relative change in viscosity with temperature.

• VI improvers (also known as viscosity modifiers) are additives that increase the viscosity of the fluid throughout its useful temperature range.

• The VI scale was set up by the Society Automotive Engineeres (SAE).

• The temperatures chosen arbitrarily for reference are 100 °F (40⁰ C) and 210 °F (100⁰C).

• The original scale only stretched between

• VI=0 (worst oil, naphthenic) and

• VI=100 (best oil, paraffinic)