Comment

Greenpeace's battle with seismic companies offshore Europe over reported injuries to whales and porpoises by acoustic airguns could pose a serious problem for the industry. If injuries are taking place, and this has not been demonstrated by qualified procedures, there will be great pressure to find alternatives to the present system of surveying.

Leonard Le Blanc

Seismic shutdown

Greenpeace's battle with seismic companies offshore Europe over reported injuries to whales and porpoises by acoustic airguns could pose a serious problem for the industry. If injuries are taking place, and this has not been demonstrated by qualified procedures, there will be great pressure to find alternatives to the present system of surveying.

There are few ocean regions where whales and porpoises do not travel, especially in deepwater frontier areas. Whales are not likely to be frightened easily, especially in migratory patterns, although surveys could be conducted between whale migrations. Porpoises, on the other hand, remain in good feeding areas for long periods of time, and could be the greater problem.

To attain the desired signal penetration energy, an acoustic or concussive signal must be substantial. There are no known substitutes for acoustics in the seismic field. Relying solely on magnetic and gravity measurements, despite the substantial technical progress made in these two technologies, would push drilling risks back into the era of 2-D seismic. Another alternative, electromagnetics, does not produce sufficient signal penetration or speed differentiation to evaluate geological formations or contents.

One measure considered by surveyors, in order to scare off potential victims, is to generate low-energy acoustic signals on startup and periodically as a seismic vessel transits one part of the survey range to another. It represents an extra cost, but a modest one compared with a change of technology.

The seismic sector should continue to push for evidence of linkage between mammal injury or disorientation and acoustic signals. However, as in other things that enter the regulatory realm, physical evidence might not be necessary. The seismic sector may want to consider its collective position if the issue goes global, and if significant political and public support adheres to Greenpeace in this dispute.

Canada's Atlantic plan

Decades ago, Newfoundland was the gateway to North America and the center of the North Atlantic fishing industry. Virtually all trans-Atlantic flights stopped in Gander for re-fueling. The nearby Grand Banks was the most prolific fishing region in the world. The advent of large jet aircraft brought re-fueling operations to a stop, and fish populations offshore collapsed. The Canadian government, in an effort to assist Newfoundland with severe unemployment and poor industry prospects, stepped in and supported the Hibernia platform field development.

Today, even though unemployment remains high, the investment is proving worthwhile. Higher oil prices will provide a return for investors, other fields nearby are made commercial by Hibernia's proximity, and a modest petroleum industry infrastructure is now in place.

The Canadian government needs to turn its attention to the gas end of the equation on the Grand Banks. Sable Island gas off Nova Scotia, now being developed by commercial interests, comprises only a portion of potential Atlantic gas reserves.

If gas injection is feasible for discoveries, or commercial gas-to-liquids conversion materializes soon, then the problem is solved. If not, then Canada must devise a plan to prevent stranding of associated reserves on the Grand Banks and limiting development opportunities. Also, Canada should consider eliminating capacity constraints on proposed gas trunklines onshore and whether these might limit future development. While planned throughput seems to exceed market demand now, gas fields deplete quickly.

The challenges of producing through pipelines crossing the Grand Banks are huge. Much of the seafloor is hard rock, and what is not is criss-crossed by iceberg gouges. The hard rock transit areas pose the greatest hurdle, since a pipeline would probably have to be trenched. Such an undertaking would be expensive, and trench grinding equipment does not yet exist. Once installed in rock, however, the shoulders of the trench would protect a pipeline from iceberg keels and anchors pulled across the seafloor. Only a seismic event or a direct hit from above would impact a rock-trenched pipeline.

Pipeline transit in soft seafloor areas to the west and south of the Grand Banks where ice gouges are present might require a 15-ft burial depth, but a shallower burial could be risk-efficient if maximum depth gouges are rare. Unless the gouges are recent, deeper areas down-current of shallower shelf areas would need only anchor protection.

The Canadian government needs to continue what it started with Hibernia by further enlarging the opportunities for Grand Banks oil and gas prospects. Development of a gas network there is a key to that expansion.

Copyright 1997 Oil & Gas Journal. All Rights Reserved.

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