Page 10 - Treating Oilfield Emulsions

Segment II Chapter 6

The Principles of Chemical Treating
Petroleum Extension-The University of Texas at Austin
I n the early days of the oil industry, treating the dispersed water droplets. Chemicals that are
was a makeshift proposition, with each lease solubleordispersible in oil and surface-active (i.e.,
handled differently. Many operators depended they dissolve in the oil and work on the surfaces
on the people in the field to treat the oil and made of the water droplets to cause them to break) are
no organized effort to detennine which chemi­ added in small amounts at some point in the
cals were most efficient at breaking emulsions. treating system. Emulsion-breaking chemicals
During this period, however, many chemicals must also be polar materials; that is, they mustbe
were found, through trial and error, to be benefi­ attracted to the emulsifying agents, which are
cial, including lye, hydrochloric acid, and soap also polar materials. This attraction is much like
powders. The chemical companies now familiar the action of two bar magnets being drawn to
to the petroleum industry got their start experi­ each other. The chemical contacts the emulsify­
menting with these chemicals. Today the princi­ ing agent and, in effect, weakens it. When the
pal business of a number of companies is the freely moving water droplets in the oil collide, the
manufactureand sale of modememulsion-break­ droplets easily merge to form larger drops that
ing compounds and other oilfield chemicals. will settle out. Figure 23 shows two samples ofthe
Several companies have research laboratories and same emulsion, one with and one without the
a force of field engineers to assist the producer in addition of an emulsion-breaking chemical.
selecting the proper chemicals and in other mat­ Chemicals used to treat reverse, oroil-in-water,
ters pertaining to treating done in the field. emulsions differ from those used to treat water­
For a chemical to work as an emulsion breaker in-oil emulsions in that they are water soluble; that
in a water-in-oil emulsion, it must be able to is, they dissolve in water so that the chemical can
deactivate the emulsifying agent that surrounds contact the surface of the oil droplets suspended

. .
. . . ..
...
.,. 10th Day
:
..... .. ..
:'.'; o~~"
• 0" • • •••:.,
.Q.." . ••••• .
• • .:" : .. 1 :
c
C
0° -.
e; .
. o· , . "'-'
. .. . .
0"
.• .. b.;- :
. . .
4 ••• ' ••• , .
. .
'. .. . -.
~
Figure 23. Two samples of the same water-in-oil emulsion maintained at the same temperature over a number of
days. Demulsifier has been added to the lower sample. No chemical has been added to the top sample.
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