In many oil and gas fields around the world, hydrocarbons are being extracted from fields that have very severe system conditions. It is now commonplace for new oil and gas fields constructed with carbon steel piping to operate at extremely high temperatures (>150°C) and it is also normal for fields to produce gas that contains CO2 or H2S in excess of 20 mol%. Consequently, corrosion inhibitors are now required to be effective under very harsh operating conditions. However, these are not the only challenges that corrosion inhibitor developers need to overcome. Corrosion inhibitors are also required to mitigate many diverse forms of corrosion including pitting, under-deposit, galvanic, top-of-line and preferential weld corrosion.
Corrosion inhibitors used in oil and gas production are normally only effective in preventing sweet or sour corrosion. However, in aging assets corrosion inhibitors may also be required to control corrosion due to the presence of oxygen and many traditional inhibitors are simply ineffective when oxygen is present. Furthermore, local environmental regulations restrict what corrosion inhibitors can be used in certain geographic locations. Finally, oil and gas fields operating in deepwater environments provide additional complexities with respect to the deliverability of the corrosion inhibitor to the subsea injection location.
This paper examines the many challenges the industry now faces in developing corrosion inhibitors for new assets, aging assets and deepwater fields. The paper also details the factors that can have a negative effect on inhibitor performance. The paper discusses the restrictions regarding what inhibitor chemistries can be used as a result of environmental regulations and operator preferences. The problems associated with monitoring corrosion inhibitor performance in the field and the considerations required before deploying an inhibitor are also explored.