Summary
The chemical application of corrosion inhibitors is a widely adopted
practice in production and processing operations in the oil and gas industry.
Particularly challenging is the development of new chemistries, which maintain
good protection of materials under a variety of conditions while being
environmentally acceptable.
This paper illustrates patented work in the chemistry of alkyl polyglucosides
(APGs) and their synergistic effect with polyaspartates (Wei).
The paper outlines the development of this inhibitor class, which
demonstrates good general inhibitor performance in a number of oilfield brines,
shows good filming characteristics under conditions of shear, and also has an
excellent environmental profile. The paper examines the base chemistry of alkyl
polyglucosides.
The paper illustrates the effect of inhibitors in a number of sweet and sour
conditions as well as under various temperature conditions in a variety of
oilfield waters. The results of laboratory tests under these conditions, such
as linear polarization resistivity (LPR) the so-called “bubble test,” and the
rotating cylinder electrode (RCE), are presented and discussed.
Environmental data on formulated products will also be given. To date, all
formulations of this chemistry have been classified for use in the UK sector as
Gold, with no substitution or other product warnings.
Introduction
Chemical inhibitors play an important role in the protection and mitigation
strategies for the retardation of corrosive process within the oil and gas
process industry (Webster et al. 1993; Dougherty 1998). A number of chemistries
have been successfully applied (de Rues and Simon Thomas 2002) in this respect,
primarily amines, quaternary salts of amines, and imidazolines (Reviews 1993),
all of which act as filming protection agents either filming on the metal
surface or a on a variety of scales [e.g., calcium carbonate deposited on these
surfaces (Hodgkiess 2004)]. In addition to filming characteristics, it is
essential that corrosion inhibitors also exhibit properties to slow the
corrosion rate usually by a combination of the following: increasing the anodic
or cathodic polarisation behavior, reducing the movement or diffusion of ions
to the metal surface, and increasing the electrical resistance of the metallic
surface.
Filming protection is the most widely used method of corrosion inhibition in
oil and gas processing and transportation (by pipeline). This is because of the
necessity of having good protection against corrosion within a highly dynamic
environment (Schmitt and Labus 1994). The mixture of crude oil, dissolved
gases, condensate, connate, and other waters (brines) can give rise to a highly
aggressive and corrosive media. To further challenge this environment, these
mixtures are often under conditions of high flow, creating a number of shear
stress conditions (Efird et al. 1993).
© 2007. Society of Petroleum Engineers
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History
- Original manuscript received:
21 March 2006
- Meeting paper published:
30 May 2006
- Revised manuscript received:
11 May 2007
- Manuscript approved:
21 July 2007
- Version of record:
20 December 2007
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