Page 213 - Petroleum and Gas Field Processing

Stabilizer’s applications, on the other hand, are justified over simple
stage separation under the following operating conditions:

The first-stage separation temperature is between 0 F and 40 F.
The first-stage separation pressure is greater than 1200 psig.

The liquid gravity of the stock tank oil is greater than 45 API.
Oil to be stabilized contains significant quantities of pentanes plus,

even though the oil gravity is less than 45 API.
Specifications are set by the market for product compositions—
obtained from an oil—that require minimum light ends.

7.5 CRUDE OIL SWEETENING
Apart from stabilization problems of ‘‘sweet’’ crude oil, ‘‘sour’’ crude oils
containing hydrogen sulfide, mercaptans, and other sulfur compounds
present unusual processing problems in oil field production facilities. The
presence of hydrogen sulfide and other sulfur compounds in the well
stream impose many constraints. Most important are the following:

Personnel safety and corrosion considerations require that H 2 S
concentration be lowered to a safe level.
Brass and copper materials are particularly reactive with sulfur
compounds; their use should be prohibited.
Sulfide stress cracking problems occur in steel structures.
Mercaptans compounds have an objectionable odor.
Along with stabilization, crude oil sweetening brings in what is called
a ‘‘dual operation,’’ which permits easier and safe downstream handling
and improves and upgrades the crude marketability.
Three general schemes are used to sweeten crude oil at the
production facilities:

Process Stripping Agent

1. Stage vaporization with Mass (gas)
stripping gas
2. Trayed stabilization with Mass (gas)
stripping gas
3. Reboiled tray stabilization Energy (heat)

1. Stage vaporization with stripping gas. This process—as its name
implies—utilizes stage separation along with a stripping agent.

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