Bundle Up; It's Winter in the Delta

Mackenzie Being Explored

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."

Image Caption

Data courtesy of Canada's National Energy Board

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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.