Summary
This paper discusses the principle and proof of concept of a novel
corrosion-management tool based on maintaining optimum corrosion-inhibitor dose
in an inhibited environment. Film-forming corrosion inhibitors typically
contain active ionic surfactant molecules, which adsorb on surfaces and form a
protective barrier against corrosion. Upon saturation of surfaces by the
inhibitor, the molecules are found in the aqueous phase as micelles or in the
oil phase as reverse micelles. The proposed technique is based on the
hypothesis that the presence of these micelles in the water phase could be used
to indicate the total surface coverage and, therefore, the optimum dose.
The technique has been applied in the laboratory simulating an actual
inhibited multiphase production system. Fluorescent markers, which are
extremely sensitive to micelle presence, have been developed and used during
the laboratory testing. Results were compared with those from standard
laboratory techniques, including interfacial tension (IFT) and particle-size
analyses (diffraction), in order to determine the efficacy for micelle
detection. Corrosion bubble tests were also used to determine any link to
inhibitor efficiency.
IFT results showed complex events occurring with increasing inhibitor
concentration. The IFT vs. inhibitor concentration curve was nonclassical,
probably because of the multicomponent nature of inhibitor formulations, but
suggested micelle formation at approximately 150 ppm. Fluorescence analysis
suggested that micelles formed starting at a 150-ppm dose. Particle-size
analysis was consistent with micelle presence beyond this concentration.
Separate experiments comparing fluorescence with corrosion rates demonstrated
an apparent nonlinear variance with inhibitor concentration, supporting the
hypothesis.
The analytical comparisons supported the underlying principles of this
micelle-detection technology. Development of a portable device is under way and
will provide an important new tool for proactive corrosion management in the
oil field as well as a useful laboratory qualification method.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
7 April 2010
- Meeting paper published:
24 May 2010
- Revised manuscript received:
20 April 2011
- Manuscript approved:
3 June 2011
- Published online:
24 January 2012
- Version of record:
11 June 2012
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