Common acid corrosion inhibitors frequently require the addition of intensifiers or contact time extenders when used in very strong acids, high temperatures, or for long contact times. Effective metal intensifiers have the severe disadvantage of being exceedingly toxic to aquatic life as well as humans. Copper salts are lethal to aquatic species at concentrations below lOppm. Antimony salts can also cause heavy metal poisoning when used in the required concentration ranges for inhibitor intensification.

Results are presented showing that a combination of low toxicity intensifiers produces an unexpected synergy and highly effective corrosion inhibitor intensifier system. For example, the use of two common intensifiers can allow contact times of 4 hours to be achieved at 300°F in 28% HC1 on common oil field tubular goods. Intensifier systems will be presented that allow a lower toxicity option to be used in mineral acid systems (e.g., HC1, HC1/HF) on N80/L80 and chrome alloy tubing. These systems can allow an adequate corrosion protection to be achieved that, until recently, was only possible with copper or antimony-based intensifiers. These systems can also be applied at lower temperatures and can significantly reduce corrosion inhibitor concentration requirements.

This development can allow high temperature acidizing to be carried out in areas where the environmental impact of the stimulation fluid is of great concern. The new technology can also cause significant savings in fluid costs by reducing the quantities of the acid corrosion inhibitor (sometimes as great as a 50% reduction). This latter benefit should also translate to better stimulation treatments by reducing both inhibitor incompatibilities with the treatment fluids and producing zones.

You can access this article if you purchase or spend a download.