Natural gas is produced in offshore wells, processed on the island and exported via tanker.
This implies that it must be placed subsurface in all circumstances, i.e. in offshore wells, not above the seabed.
They were obscured in part by the long gap between the time incentives are offered and when new offshore wells start producing.
The BOP equipment technology has been adapted and used in offshore wells since the 1960s.
Panarctic's ice island wells were not the first offshore wells in the Canadian north.
The company is planning to spend $1.2bn on drilling in the Arctic area, but its first two offshore wells have not found gas in commercial quantities.
The design became the basis for a safety device used on offshore wells.
The latest figures (1987) show we received 14.3 percent of our domestic crude oil from offshore wells, and 25.3 percent of our natural gas.
More than half of the company's output of natural gas comes from offshore wells in the gulf, where it is the second-largest producer, after Chevron.
Tankers have a far worse environmental record than offshore wells.