What are the physical properties of crude oil?

Answer 1

Some of the most important physical properties of crude oil include:

oAPI

oAPI = (141.5/SG 15oF) - 131.5 The purpose of this equation was to extend the range of the specific gravity scale. Crude oil SG changes, although small, may be important.

Crude Oils oAPI = 10 - 50

Higher oAPI, more paraffinic crude, higher yields of gasoline.

Lower oAPI, more aromatic crude, lower yields of gasoline.

Viscosity

Resistance to flow, usually measured @ 100oF in centistokes (kinimatic viscosity)

Pour Point

Measured by ASTM D-97 - temperature at which oil ceases to flow. Diesel may contain waxes, smaller than candle wax, which could solidify in cold weather.

Flash Point

Temperature above which the oil will spontaneously combust. Fractions in vacuum tower are the least combustible. They are the heaviest.

Vapor Pressure

Measured by ASTM D-323. Also know as Reid vapor pressure (RVP). True vapor pressure is usually 5-9% > RVP

Carbon Residue

The solid residue (%wt) remaining after heating to coking temperatures (700-800oC)

ASTM D-524 Ramsbottom Carbon

ASTM D-189 Conradson Carbon

CCR incr. then Asphaltene incr.

Salt Content

Measured by ASTM - 3230 (lb NaCl/1000 bbl)

Desalting is necessary because NaCl content > 10 lbs/1000 bbl leads to corrosion

Metals

Measured by EPA Method 3040 These include Ni, V, Ag, Hg, Na, and Ca. Metals can cause catalyst deactivation and corrosion.

Sediment and Water

Measured by ASTM D - 96 These inorganic particles can lead to operational problems.

Acidity

Measured by ASTM - 664

Sulfur

Measured by ASTM D - 129, 1552, 2622

Sour crudes > 0.5 wt% and sweet crudes < 0.5 wt%. Today it is difficult to find crudes below 1% sulfur.

Answer 2

One of the most important properties of motor oil in maintaining a lubricating film between moving parts is its viscosity