| NEW YORK
NEW YORK Feb 26 A study of a fresh sample of
crude oil from the Bakken shale in North Dakota published this
week showed sharply lower levels of volatile vapors compared to
previous tests, potentially raising new questions about the
danger of shipping it by rail.
The latest data from Marathon Petroleum's Capline
Pipeline unit, which publishes so-called "assays" on the quality
of over 100 types of crude on its website, showed a sharp fall
in the oil's vapor pressure, a common measure of a fuel's
ability to evaporate and give off combustible gases.
While the data offers only a single snapshot of the
properties for a batch of so-called "North Dakota Sweet", a term
for Bakken crude, it may raise more questions about the
combustibility of the oil, which has been cited in several fiery
derailments in recent months.
The data emerges just as U.S. regulators impose new rules
requiring more testing of Bakken crude for fear it is prone to
explosion during accidents. Industry officials are appearing
before a House committee in Washington on Wednesday to discuss
Capline's latest Bakken assay, dated 14 January, was posted
on its website this week, shortly after a Wall Street Journal
story on Monday used older Capline data to show Bakken crude
carries more combustible gases than other varieties. While
Bakken's ultra-light properties are generally well known, hard
data is rarely made public.
Regulators are seeking more information on Bakken crude from
oil shippers and are also conducting their own data collection
and sampling. It is not clear when or if those results will be
Capline's newest test showed a vapor pressure reading of
5.94 pounds per square inch (psi). The reading compares with a
psi of 8.75 for a test done in February 2013 and is nearly 4
pounds per square inch lower than the highest reading, 9.7 psi,
recorded by Capline in December 2010. A higher psi reading
generally indicates a liquid fuel is more prone to give off
It was not clear why the rate had declined so sharply, or
whether that decline is broadly reflective of the region as a
whole. One expert who reviewed the data said the wide
fluctuation appeared unusual, but not conclusive of any trend.
"I would expect it to go up and down, it's going to vary,
but that's a big drop," Connie M. Hendrickson, chemist with
Arkon Consultants in Dallas, Texas, told Reuters. "Without extra
sampling and extra testing, we just don't know."
A spokesman for Marathon declined to comment on the
decrease, other than to say the firm has "a process in place to
test crude oil for quality oversight purposes". The samples are
generally taken at the same spot on the pipeline, the spokesman
It is not clear how much Bakken runs through the Capline, a
1.3 million barrels-per-day (bpd) pipeline running north from
St. James, Louisiana, to Illinois. The Marathon spokesman
declined to provide operating rates for the pipeline.
To be sure, Capline's latest data still show Bakken crude
ranks higher in volatility than most other crudes, based on
vapor pressure tests conducted by the company. At the 5.94 psi,
for example, Capline's latest Bakken sample still ranks more
than double that of Light Louisiana Sweet crude, which tested at
2.38 psi in May 2013.
Still, the wider range of readings and the infrequency of
the testing suggests there remains much uncertainty about the
quality of Bakken crude.
Other data sets have suggested not only that the crude is
light by its nature - Bakken reserves are rich in so-called
"light ends" like butane, propane and other byproducts of
petroleum - but that it is also growing lighter.
Refiner Tesoro Corp. said in a 2013 presentation
that its purchases of crude sourced from North Dakota's Bakken
region have increased in volatility, topping readings of 12 psi
Some lawmakers have asked for more data to aid regulatory
efforts on this issue.
"It is not in anyone's best interest to knee-jerk a response
without data," North Dakota Senator Heidi Heitkamp said in an
interview this week.