November 25, 2011 / 9:40 PM / in 6 years

Alberta study disputes oil sands corrosion claims

CALGARY, Alberta (Reuters) - An Alberta study has found that crude from the province’s oil sands is no more corrosive to pipelines than conventional oil, but it points out there is no definitive peer-reviewed research on the issue, which has played a role in Keystone XL pipeline controversy.

A 29-page review of available data by Alberta Innovates, a government-owned research corporation, addressed warnings by environmental groups that crude from the northern Alberta oil sands was more damaging to pipeline walls in several different ways, increasing risks of oil spills.

The study found there are differences in the chemical makeup of the types of oil, but not necessarily in corrosive qualities.

The paper made several recommendations, including urging Alberta’s regulator, the Energy Resources Conservation Board, to start separating safety and operating statistics for pipelines that carry oil sands crude from those that ship conventional oil to allow better information gathering.

The paper, published this month, was written by Jenny Been, a specialist in Alberta Innovates’ corrosion-engineering and advanced materials section. It was prepared for John Zhou of the agency’s energy and environment solutions division.

It is not clear what weight the research carries and what the next steps are. Zhou and other officials at his division were not available for comment.

Corrosion fears were part of the controversy surrounding TransCanada Corp’s $7 billion plan to build the Keystone XL pipeline to Texas from the Alberta oil sands. The plan is now on hold after the U.S. State Department pushed back a go-ahead decision by more than a year. The issue has arisen with other projects aimed at shipping crude from the tar sands, the world’s third-largest oil deposit.

Despite a push by Canada and its oil industry to boost exports and staunch opposition from environmental groups such as the Natural Resources Defense Council (NRDC), there is little, if any, dedicated research on the impact of the oil in question, bitumen mixed with lighter diluting hydrocarbons, called “dilbit”.

New York-based NRDC released a study early this year that spelled out the concerns and called for the U.S. pipeline safety authority to commission research. The Alberta paper said the NRDC did an “excellent job” summarizing the issues and also points out the lack of a formal peer-reviewed study.

There is no indication that releasing the Alberta Innovates paper to regulators or media would have swayed the State Department in favor of greenlighting Keystone XL. But it may have helped calm some fears over risks of oil spills in environmentally sensitive areas, such Nebraska’s Sand Hills.

In the paper, Been reviewed information from several sources and found dilbit crudes had acid, sulfur and chloride salt concentrations comparable to many conventional crudes.

The one exception is a variation called “dilsynbit”, which is bitumen mixed with light synthetic crude. It has higher concentrations of solids but still well below the limits set by regulators and pipeline operators, she wrote.

Been pointed out that those ingredients can cause corrosion at temperatures above 200 C (392 F) at refineries, but are too stable at lower pipeline temperatures to cause such damage.

The research highlighted one risk, however - the impact of the buildup of sludge, made up of clay particles, water and oil, in pipelines. “The corrosivity of these sludges varies, but seems to be linked to water content, which can exceed 10 percent, and large bacterial populations,” she said.

Sludge is not unique to pipelines carrying dilbit. However, the paper recommended that the compatibility of diluent and bitumen should be studied to find out if that plays any role in the formation of sludge.

The paper also urged support for a “downstream quality database” being developed by Crude Quality Inc and its industry partners. Crude Quality is an Edmonton, Alberta-based company that compiles data on Canadian oil types.

“It will be a valuable resource for the evaluation of sludge deposition and underdeposit corrosion during transportation,” Been said.

Editing by Peter Galloway

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