It's mid-August in the land of the midnight sun. High
above the Arctic Circle, barges laden with seismic and drilling
equipment are moving northwards, navigating the myriad of channels
that comprise the Mackenzie River.
Where Canada's longest river meets the Beaufort Sea, it fans out
to form the Mackenzie Delta, an area of 13,500 square kilometers
-- an area where the distinctions between land and water blur.
After a 10-15 year hiatus, oil and gas exploration in Canada's
North -- from the 60th parallel to north of the Arctic Circle --
is heating up again as large multinational Canadian and American
E&P companies shift their focus to tap the resources of this
northern frontier.
According to a 1998 resource assessment by the National Energy
Board (NEB) of Canada, the Mackenzie Delta and adjacent Beaufort
Sea are estimated to contain one billion barrels of recoverable
oil and nine Tcf of marketable gas. The NEB also estimates that
an additional six billion barrels of oil and another 55 Tcf of gas
are yet to be discovered in the region.
Propelled by strong natural gas prices and the existence of 30
Tcf of stranded gas reserves in the North Slope of Alaska, the race
is on to discover Canadian reserves to justify the proposed Mackenzie
Valley Pipeline Route, the direct competitor to the proposed Alaska
Highway Route.
Most Aboriginal land claims have been settled, placing the First
Nations in the driver's seat of the regulatory process and the economic
development of the North.
Seismic acquisition is at the leading edge of this new exploration
phase; innovative seismic technologies are being developed to deal
with this harsh, unforgiving climate where winter temperatures often
dip below minus 40 degrees Celsius, the temperature at which steel
becomes brittle and starts to fail.
At the forefront of this new wave of seismic activity, is the
imperative to minimize the environmental footprint of field operations
in these fragile northern ecosystems.
The monumental task of mobilizing equipment and people to the
Canadian north "forces you to think outside the box," says Randy
Strandberg, supervisor of Geophysical Operations for Calgary-based
Petro-Canada. "Project management becomes an art."
Ice Is Nice
By late September -- before the water levels drop in the Mackenzie
River and ice starts forming -- all of the seismic equipment must
be barged to staging areas for winter operations. From December
15 to April 15 -- the window for drilling and seismic operations
-- the Mackenzie River is transformed into a transportation corridor
of ice roads and ice bridges.
"Our biggest challenge is the ice thickness on the rivers and
lakes," explains Mike Smith, general manager of Canadian operations
for Veritas DGC. "We are constantly monitoring it."
About 106 centimeters (or 42 inches) of ice is required to support
heavy equipment, like vibroseis trucks.
Early in the winter season, the companies plow snow and flood
river channels, building up to six inches of ice per day. Daily,
seismic contractors auger holes into the ice, coring and measuring
its thickness and the water flow below.
Ground Penetrating Radar (GPR) units are towed behind trucks that
transect the frozen waterways, profiling the ice thickness and calibrating
it against the data from the auger holes. Strandberg uses the term
"rotten ice" to describe weak ice that contains large holes detected
using GPR and which may not be visible from the surface.
Safety of personnel in this unforgiving environment is of paramount
importance.
"From our base in Inuvik, we know, in real time, the location
of every vehicle in the Mackenzie Delta," says Al Chatenay, Canada
Manager of WesternGeco. That's because WesternGeco has installed
a Vehicle Tracking System -- complete with a GPS unit -- in each
vehicle.
The company can send text messages, via a radio modem, to each
vehicle operator with instructions -- including GPS coordinates
for a computerized map.
Challenging Factors
In
order to reduce impacts on the tundra, contractors use rubber tracked
vibroseis trucks and, borrowing from the experiences of the Canadian
and Swedish armies, rubber tracked vehicles designed for northern
operations. Seismic "sleigh" camps with closed sewage and garbage
systems are transported in the field where they travel over the
layer of snow that insulates the tundra below.
WesternGeco's "zero leak" vehicle refueling system -- similar
to that used in the airline industry -- injects fuel using a hydraulic
coupling system, ensuring no spillage.
During the 24 hours of darkness in the height of winter, helicopters
can't safely assist in seismic operations; nor can helicopters fly
during whiteouts or blizzards, which can reduce visibility to a
couple of feet. Acquisition techniques include the adaptation of
spiked marsh geophones -- identical to those used in the Mississippi
delta -- that are planted, using long poles, in order to get a good
coupling with the ground, which may be covered by up to 10 feet
of snow.
Ned Frey, general manager of frontiers for Calgary-based Anderson
Exploration, suggests that the differences in climate and culture,
combined with the logistical obstacles, make the North a unique
place to explore for oil and gas reserves.
"We approach the North as if it was an international venture,"
said Frey, an AAPG member.
Anderson has staked a significant part of its future in the North;
in a 1999 land sale, the company was the successful bidder in six
blocks (Anderson-operated and non-operated) totaling more than one
million acres. Anderson is committed to spend $275 million during
the next five years for seismic and drilling activities in these
six blocks.
"The Beaufort Sea and Mackenzie Delta have world class reserves,"
Frey said, "and the finds to date back that up."
Frey's sentiments are echoed by Jeff Bever, Petro-Canada's team
leader of Northern exploration, who describes the area as a "frontier
play with high risk and high reward."
Apart from the logistical challenges of shooting seismic data,
Bever cites the technical challenges of processing and interpreting
these seismic data -- up to 700 meters of permafrost (which is often
replaced by unconsolidated deltaic sediments lying under waterways)
creates weathering and acoustic problems, generating seismic multiples.
To overcome this technical issue -- and to compress the timelines
required to select drilling locations for the following winter --
Petro-Canada regularly sends its seismic data to two processing
houses where the data are processed simultaneously, focusing on
attribute analysis and structural imaging.
Environmentally Friendly
By mid-August, the Inuits had finished their traditional harvesting
of beluga whales in the shallow, coastal waters of the Beaufort
Sea. As the beluga whales headed out to sea -- the beginning of
their migration route -- Anderson's offshore operations commenced
with the acquisition of a 1,600-square-kilometer 3-D seismic program.
It's the first 3-D survey ever acquired in the Beaufort Sea --
on either the Alaskan or Canadian side.
The WesternGeco seismic vessel -- a Canadian-built Class Two icebreaker
retrofitted for seismic data acquisition -- had just completed its
long journey from Galveston through the Panama Canal, up to Alaska
and across to the Canadian side of the Beaufort Sea. Because the
3-D program can't be completed during the short Arctic summer, the
vessel plans to over-winter, completing the remainder of the program
next summer.
Anderson has initiated programs to mitigate environmental damage
of its marine seismic operations, including the acquisition of a
bathymetric survey to map the seafloor.
During the 3-D survey, WesternGeco will employ a solid marine
streamer that is foam-filled as opposed to conventional, oil-filled
streamers. Steve Carter, WesternGeco's marine account manager for
North and South America, describes the solid marine streamer as
"environmentally-friendly because it doesn't contain oil for buoyancy."
Oil-filled streamer cables, Carter said, contain up to 60 gallons
of oil per 100-meter section -- oil that could potentially leak
into the marine ecosystem.
In addition to placing marine mammal monitors aboard the seismic
vessel, WesternGeco will fly aerial surveys to monitor marine mammals.