Anne Shafizadeh of Chevron Texaco introduced the new, commercially available High Acid Crudes (HAC), their supply and demand balances, their common markets and the opportunistic economics of running these crudes. HAC’s are defined as those crudes with a Total Acid Number (TAN) of greater than 1.0. This can be very misleading because TAN, by itself, is not a good indicator of how corrosive a given crude might be in a refinery. Naphthenic acids, which are only a part of TAN, generally cause the most corrosion.

Crudes with high acidity will likely become more prevalent as light crude production diminishes. It is predicted that HAC will make up 10% of the world’s oil supply by 2010. Chevron Texaco HAC production is predicted to increase 50% within that same time frame. HAC from the Americas contributes greatly to the world supply, but these crudes are prevalent in many other areas as well. Many North American refineries are capable of running HAC’s and absorb the Americas’ supply plus much of the excess from other parts of the globe, such as West Africa.

High Acid Crudes, like every other crude currently available, have both disadvantage and advantages in a specific refinery. However, there seems to be unwillingness on the part of many refiners to run HAC's. There are viable solutions, such as metallurgy and corrosion inhibition, to the perceived problems of running High Acid Crudes. Considering the current availability and future supply increase, there can be favorable economics to trying High Acid Crude. Acid grades have traditionally traded below the relative refining value versus non-acid grades; this effect has been termed the "Acid Discount" or "Refining Benefit". Anne ran though several examples of how the widening acid discount can be used to your refinery’s advantage. This is especially true considering that refinery upgrades have not kept pace with the increasing supply, so there is a perceived surplus of High Acid Crudes.

Anne and her colleagues at Chevron Texaco are available to discuss individual opportunities for specific refineries. Anne can be reached on Anne.Shafizadeh@chevrontexaco.com

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Mr. Gregg McAteer of Ondeo Nalco Energy Services continued the presentation with a discussion on mitigation of potential high acidity problems. Risk based assessment of the refinery facilities can define the areas of concern when naphthenic acid containing crudes are processed. High temperature fast flow loop studies can be used to accurately define the corrosion potential and provide information on the order and magnitude. Fast flow loop analysis can also be used to conduct metallurgy studies and the effectiveness of corrosion inhibitors applied to the system. Studies and field experience have shown that corrosion inhibitors can be highly effective for the control of naphthenic acid corrosion.

In addition to possible naphthenic acid corrosion, opportunity crudes can also have associated processing problems such as desalter upsets, preheat and reactor bed fouling, side-cut stability and cetane issues. Alleviation tactics exist for all these ancillary problems which can be addressed in a timely manner if the refinery is prepared. With proper mitigation strategies, metallurgy and / or the application of naphthenic corrosion inhibitors, opportunity crudes can now be safely processed at higher levels than was possible in the past.

Please contact Gregg McAteer at grmcateer@ondeo-nes.com for details on his presentation or to discuss High Acid Crudes processing strategies.