This paper discusses our successful efforts in developing new all oxygen based acid corrosion inhibitors that are biodegradable, non-bioaccumulating and low in toxicity, that meet industry standards for protection of carbon steel oilfield tubing up to 120°C (~250°F). These are environmentally acceptable inhibitors with the appropriate dispersibility and performance characteristics needed for critical applications in environmentally sensitive areas.

Matrix acidizing treatments are employed to remove reservoir damage by introducing acidic solutions (usually hydrochloric acid, HCl) into the formation at pressures below those used in fracturing operations. HCl is also used in acid fracturing as an alternative to proppant fracturing. The use of HCl requires that an effective acid corrosion inhibitor be included in the treatment package to protect the well's hardware.

Quaternary amines, including pyridine and quinoline quats, are frequently used as the active components in many corrosion inhibitors. While possessing excellent inhibition properties, the compounds are toxic to many forms of sea life, as well as to humans. Quats have been the backbone of the HCl acid corrosion control efforts for many years since they are very effective inhibitors and were often beneficial in improving the compatibility of the inhibitors with the HCl formulations. While oxygen based acid corrosion inhibitors are also in commercial use, they are usually formulated in conjunction with quats.

As environmental regulations become more stringent, some compounds are being banned or are listed for substitution. In the United States and Canada, producers and service companies alike are developing product standards to improve their portfolios in an effort to proactively address environmental concerns and to be responsible corporate citizens. Our efforts were focused on developing oxygen-based inhibitors that met or exceeded the current regulations and requirements established by various governments, producers and service companies. The target was to formulate an inhibitor that contained only environmentally acceptable components, and specifically excluding propargyl alcohol, pyridine and quinoline quats, US EPA Priority Pollutants, nonylphenol ethoxylates (NPE), BTEX, methanol, ethylene glycol and ethylene glycol monobutyl ether (EGMBE). Developing an all oxygen-based inhibitor proved to be quite challenging.

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