Victor’s Insider Scoop on Part of My Previous Life Working in the High Arctic …
March 15th, 2010 | top of page
This article and photos were first published in the Summer 1981 Issue of North/Nord magazine under the title Another Day on the Arctic Seismic Line.
The whine of the helicopter engine starting evokes a Pavlovian response from the survey crew signaling us to pull on our heavy arctic parkas and mukluks. By the time the turbine engine has reached its operating speed we are buckled inside the fuselage of the Hughes 500C waiting for the pilot to crank some pitch on the rotor blades and lift off amid a flurry of flying snow crystals.
Off to Work into the Midnight Sun
Sitting opposite me in the cramped, supply– laden rear compartment of the helicopter is the head chairman, Jan Miller. I had met Jan two years before in Lake Louise where, as a result at our common interest in mountaineering, we had become close friends. His swarthy, bearded face grins at me from behind his Vuarnets as the chopper eases off the ice and heads towards the Kristoffer Bay.
In the co-pilot’s seat is Bill Anderson the surveyor. Bill chats with the pilot over a headset informing him of our plan of action for the day and advising him of our pick–up location at the day’s end. Another day on a seismic line high in the Canadian Archipelago has begun.
Seismic exploration is based on the principles of the transmission and reflection of sound waves from differing layers of the earth’s strata. On land the sound waves are generated by explosions set off in holes drilled into the ground. In, or more accurately, on arctic seas the sound waves are created by the detonation of an explosive (Aquaflex) which has been positioned under the bottom surface of the ice.
The sound waves propagate downwards through the water, strike the various layers and formations that make up the sea bed and are then reflected back upwards to the ice surface where sensitive recording devices, called geophones hear the vibrations. The strengths and time–lags of these recorded waves can be interpreted and correlated by geophysicists to provide information about the probability of natural gas in the strata underlying the sea bed.
The area of investigation, or prospect, is composed of a grid of seismic lines that are set out on the ice by the survey crew. Each line, which can vary from 3 km to 50 km in length, is divided Into a series of shot–points that are placed at 67 meter intervals and marked by a small pin–flag.
After the surveyors have established the line, the drilling crew augers through ice that can run from 2.5 to 9 meters thick and places an Aquaflex charge down the hole. The lay–down crew follows next and is responsible for stringing out a 3.2 km length of cable along the line and connecting geophones to the cable at every shot–point. The recording vehicle plugs into the cable and, employing a radio–synchronizer, transmits a signal to the shooters vehicle which contains a special receiver that is connected to a charge.
This signal simultaneously detonates the Aquaflex and starts a multi-track recording device to store the signals from the resulting sound waves. The shooter then proceeds to the next charge and the process is repeated. At the end of the seismic line the pick–up crew gathers the cable and geophones which they transport to the lay–down vehicle. The operation continues in this leap–frog fashion until signals have been recorded along the entire line.
The methodology of the survey crew is relatively straightforward. The surveyor, employing his transit and some basic trigonometric calculations, kicks–off a prospect by basing its position and orientation on two trig–stations (survey markers on a nearby landmass whose latitude and longitude are known very precisely). Once he has established the direction of the line by lining up three or four pieces of fluorescently– painted lath, the surveyor is responsible for keeping the line straight. He does this by driving the survey vehicle in the direction of the line and stops approximately every kilometer or so and sights back down the line with the transit positioning it such that all the fluorescent sticks line up. He then inserts a new piece of lath directly beneath the transit extending the line. The chainmen walk along the line using a 67 m length of aircraft linkage cable (but known as a chain) as a ruler and insert a pin–flag in the snow marking each shot–point.
Jan Miller’s Rime-Coated Beard @ -40F
Everyone does their job, and it all works, even on the sea ice of the High Arctic.
After a 20 minute helicopter flight out to the Kristoffer Bay prospect we touch down on the frozen ocean next to our twin–tracked survey vehicle. While Jan and I transfer lath and jerry cans of gasoline from the helicopter to the vehicle, Bill eases into the driver’s seat and begins removing the engine cowling. The sometimes lengthy process of starting the nocturnally frozen four-cylinder engine is reduced somewhat by employing a propane–fired block heater to thin the -40° C crankcase oil.
Shortly after the helicopter takes off in a roar for camp the silence of the frozen arctic sea is broken again as Bill fires the engine info life aided by a shot of ether sprayed into the open mouth of its carburetor.
After we down a thermos of hot tea inside the vehicle, Bill drives off ahead to survey the line leaving Jan and I behind to chain along his northward path.
With bundles of red and blue pin–flags grasped in a heavily mitted hand and the surveyor’s chain tied to his left arm Jan begins to walk along the line.
We both have to take care to avert our faces from the brisk headwind. Even so, a protective layer of rime soon builds up on our beards and balaclavas. I follow alongside the dragging end of the chain. As I neared the first pin-flag I pick the chain up and give it a gentle tug signaling Jan to turn around, tighten the chain and insert a pin–flag exactly at the 67 m marker. The routine nature of the chaining process allows us to fall into an even rhythm resulting in a smooth pace and accurate pin–flag placements.
This article is continued in the March issue of Phoenix Commercial Real Estate Deals & More which will be sent out in the next few days.
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