Page 206 - Petroleum and Gas Field Processing

Gas: dissolved gases in varying amounts depending on the
gas–oil ratio (GOR)
Hydrogen Sulfide: up to 1000 ppm by weight
(b) After treatment (dual-purpose operation): Sour wet crude
must be treated to make it safe and environmentally acceptable
for storage, processing, and export. Therefore, removing water
and salt, as in Chapters 5 and 6, respectively, is mandatory
to avoid corrosion; separation of gases and H 2 S will make
crude oil safe and environmentally acceptable to handle.

Water content (B.S.&W.): 0.3% by volume, maximum
Salt content: 10–20 lbs salt (NaCl) per 1000 barrels oil (PTB)
Vapor pressure: 5–20 psia RVP (Reid vapor pressure)
H 2 S: 10–100 ppmw
Crude oil is considered ‘‘sweet’’ if the dangerous acidic gases are
removed from it. On the other hand, it is classified as ‘‘sour’’ if it contains
3
as much as 0.05 ft of dissolved H 2 S in 100 gal of oil. Hydrogen sulfide gas
is a poison hazard because 0.1% in air is toxically fatal in 30 min.
Additional processing is mandatory—via this dual operation—in order to
release any residual associated gases along with H 2 S present in the crude.
Prior to stabilization, crude oil is usually directed to a spheroid for storage
in order to reduce its pressure to very near atmospheric, as shown in
Figure 1.

Figure 1 Typical spheroid for oil storage prior to stabilization.

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.