Crude Oil Composition

[Ashjanj]

Hi all,

I need information on crude oil composition with API gravity with the range of 34.5 - 36.4.

Any information will be appreciated.

 

[DaEarl]

This is a strange question. The refinery you are working at should have a receipt of the crude they are charging to your units and have a breakdown by percent of each kind (i.e. Kuwaiti Light, Qua Iboe, Urals, Etc.). Also, the crude should have an assay for the content of sulfur by wt%, API gravity by type, etc.

Use the lab assays that tell you the percent of each kind of crude that is present and calculate the API gravity using simple math for the whole mixture.

Nobody could possibly tell you the composition based on stating that the crude's API is 35. Most crude is a blend of many different kinds.

 

[25362]

In addition to RKCMurphy's message, the elemental composition wt-% ranges for almost all crude oils -as published quite a time ago- is:

Carbon 83.9-86.8
Hydrogen 11.0-14.0
Sulphur 0.06-8.00
Nitrogen 0.02-1.70
Oxygen 0.08-1.82
Metals 0.00-0.14

Evidently in lighter crude oils the hydrogen content would tend toward its higher limit.

Some 70 years ago the US Bureau of Mines established a general scheme for the classification of crudes based on the specific gravity of two fractions (key fractions) from a standardized method of fractionation of the crude. From the specific gravity (or API gravity) of these two fractions, the crude is assigned to one of nine classes ranging from Paraffinic to Naphthenic.

When total analysis of fractions is practicable two groups of characterization (not too accurate) methods are applicable.
One group uses sets of physical constants to describe, by means of factors or indices, the predominant chemical character of a fraction.
The other group, based on structural group analysis, describes the character of a fraction in terms of the elements making up an imaginary average molecule with chemical or physical properties of the sum of the individual components, according to their concentration.

 

[mbeychok]

Ashjanji:

You might find what you need at this data base of crude oil and other oil assays:

http://www.etc-cte.ec.gc.ca/databases/OilProperties/Default.aspx

For the API range in which you are interested, try looking at the assays of these crude oils:

Arabian light, Basrah light, Iranian light or Alberta

Milton Beychok
(Visit me at www.air-dispersion.com)
.