Page 67 - Petroleum and Gas Field Processing

Salt Content
Salt content is typically expressed as pounds of salt (sodium chloride,
NaCl) per 1000 barrels of oil (PTB). Salts in crude oil and in heavier
products may create serious corrosion problems, especially in the top-
tower zone and the overhead condensers in distillation columns.

Sulfur

This is the percentage by weight (or ppm) of total sulfur content
determined experimentally in a sample of oil or its product. The sulfur
content of crude oils is taken into consideration in addition to the API
gravity in determining their commercial values. It has been reported that
heavier crude oils may have a high sulfur content [2].
Hydrogen Sulfide

Hydrogen sulfide dissolved in a crude oil or its products is determined and
measured in parts per million. It is a toxic gas that can evolve during
storage or in the processing of hydrocarbons.
The above tests represent many properties for the crude oils that are
routinely measured because they affect the transportation and storage
facilities. In addition, these properties define what products can be obtained
from a crude oil and contribute effectively to safety and environmental
aspects. The price of a crude oil is influenced by most of these properties.
To conclude, it can be stated that light and low-sulfur crude oils are
worth more than heavy and high-sulfur ones. One can summarize the two
approaches of examining crude oils as follows:

1. Chemical composition
2. Physical properties:
(a) API, S, salt, metals, nitrogen and so forth
(b) Distillation: ASTM, TBP, EFV
(c) Correlations: Kw, Ind
where TBP is true boiling point, EFV is equilibrium flash vaporization,
Kw is Watson characterization factor, IND is U.S. Bureau of Mines
correlation index.

2.3 CRUDE OIL COMPARISONS AND CRUDE OIL ASSAY

In order to establish a basis for the comparison between different types of
crude oil, it is necessary to produce experimental data in the form of what is

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