Ion Geophysical conducts in-ice basin-wide Beaufort Sea survey

Ion Geophysical carried out its planned basin-wide 2-D seismic survey in Alaska’s Beaufort Sea in the early winter of 2012, Ed Nelson, the company’s geophysical project manager, told the National Marine Fisheries Service’s Arctic Open Water Meeting on March 7. The company completed about 1,844 kilometers of seismic lines, about 25 percent of the line-mileage of the originally planned program, Nelson said.

Nelson told Petroleum News that the reduction in the size of the survey mainly resulted from a commercial decision to start the survey later than originally planned.

For the survey, the seismic survey vessel Geo Arctic, accompanied by the icebreaker Polar Prince, left Nome on Oct. 11, starting seismic data collection in the eastern Beaufort Sea on Oct. 24, Nelson told the meeting. Ion has developed a survey technique involving an icebreaker and survey vessel operating in tandem, with the seismic sound recorders towed beneath the water surface. The technique enables surveying to take place through the sea-ice cover of early winter, after the period of bowhead whale migration and subsistence whale hunting in the Beaufort Sea.

After shooting a series of lines in the Beaufort, the survey vessel transited to the Chukchi Sea between Nov. 9 and 13. Ion had planned to run a seismic line across to the northern Chukchi Sea, to tie into a basin-wide survey that the company carried out in the Chukchi a few years ago. However, with too much winter ice already present in the north, the vessels ran a more southerly tie-line in the central Chukchi, completing the survey on Nov. 15, Nelson said.

—Alan Bailey