Sean Reilly, Talisman
Natural gas, conventional crude oil and bitumen contain heavy metals in trace amounts and their
production, processing and use can contribute to emissions of heavy metals to the environment.
Some of these elements, such as mercury, are potentially toxic and can lead to damage to
processing equipment. Due to its toxicity, mercury has been studied and characterized in several
studies from the United States and Europe.
The objective of this project was to review the existing literature and data available on heavy
metals concentrations and potential emissions from the oil, gas and bitumen industry. This
interim report would provide the basis for further work, if necessary, to better characterize these
Based on a review of the open literature, the following observations are made on the potential for
heavy metals emissions from natural gas, oil and bitumen production and processing in Alberta:
1. Studies of U.S. natural gas deposits suggest that mercury in North American natural gas
is typically low, from 0.005 to 0.04 ?g/m3. The existing data on Alberta natural gas
indicate that most Alberta gas contains less than 0.08 ?g/m3.
2. Reported data on heavy metals content of Alberta crude oil sampled near the well head
was from a 1975 study of 88 samples. The average mercury content was 50.9 ppb, with a
range from 1.6 to 399 ppb.
3. Mercury content in conventional oil as delivered to the refinery was well characterized in
recent studies using modern sampling and analysis methods. The average mercury
content of Western Canadian crude feeds was 1.6 ppb, in contrast to the average 50.9 ppb
reported for the wellhead samples.
4. Bitumen contains higher levels of trace elements than conventional crude. Only limited
data was available for mercury content. Based on analysis of diluted bitumen and
synthetic crude feeds to a refinery, bitumen contains 5 to 11 ppb while synthetic crude
contains 0.4 to 1.6 ppb.
5. There is little information on mercury or other heavy metal concentrations in the various
pathways for emissions to the environment, such as solution gas flaring, refinery gas
combustion and tank vents.
Further work is recommended to better characterize potential heavy metal emissions to the
environment from the natural gas, conventional crude and bitumen production and processing
industry. Considering annual production rates and the estimate of mercury concentrations from
the available information, the recommended highest priority for further work is to better
characterize the potential emissions of heavy metals to the environment during bitumen
production and processing. Both the natural gas and conventional crude well head data is over
20 years old and could benefit from analysis with newer sampling and analysis techniques with
lower detection limits. In particular, the existing data shows a significant difference between
mercury concentration in crude samples collected near the wellhead and samples of crude feed
collected at refineries.