With modern drilling technology and drilling experience in the state's major oil and gas basins, blowouts have not been common in recent years, according to the Alaska Oil and Gas Conservation Commission.
The Aurora well hit an unexpected shallow gas pocket, forcing a lubricant called drilling mud to back up and out of the drilling hole. It was controlled in less than 24 hours.
Blowouts occur when a well is being drilled or completed and while there is a rig on the well. The commission identified 10 on the North Slope since 1949 -- the most recent was in 1994 -- and eight in the Cook Inlet basin, the most recent this year, but the last prior to that in 1987. Moquawkie is on the western shore of Cook Inlet.
Scott Pfoff, president of Aurora Gas, said there was no fire at the Moquawkie blowout on Sept. 28. In early October he said that since getting the well back to normal operations Aurora had run and cemented surface casing and was ready to resume drilling.
Navy mishaps
State oil and gas commissioner Dan Seamount said the earliest known blowouts in Alaska occurred in the 1940s and 1950s, when the Navy was drilling in what was then Naval Petroleum Reserve No. 4, now the National Petroleum Reserve-Alaska, on the North Slope. Seamount said those early blowouts "were mainly due to poor drilling practices which are not used today."
Commissioner Cathy Foerster, the petroleum engineer on the commission, said the three things that make the biggest difference in the reduced number of blowouts are, "in order: technology, experience and regulation. ... We wouldn't let them drill the way that they'd do it back then; but they wouldn't want to, either, because of technology and experience."
She said regulation is the third factor, behind improved technology and experience.
New technology prevents most conditions that resulted in past blowouts, Seamount said.
While there have been no blowouts at Point Thomson on the eastern side of the North Slope, Foerster said early well control incidents -- where the operator kept wells under control so no blowout occurred -- illustrate the experience factor. Alaska State A-1, drilled by Exxon on Flaxman Island in 1975, hit abnormal pressures below 12,000 feet.
"They're drilling with thousands and thousands of feet of open hole in this area where they don't know anything and they have a problem," she said.
The next well control situation in the Point Thomson area occurred six years later at Challenge Island No. 1, with a different operator -- Sohio Alaska Petroleum, now BP. They still had well-control issues, but they'd learned from the earlier well and added an extra string of pipe: "As you get your experience, you put your coping mechanisms in place," she said.
Visible from Anchorage
Two Cook Inlet blowouts, both in 1962 at Pan American-operated wells, were notable, one visually, the other legally.
Cook Inlet State No. 1 was the state's most visible blowout: the gas was flared and because it took more than a year to bring the well under control, the burning gas became a beacon for pilots in Cook Inlet. It produced a flame visible in Anchorage, said Commissioner John Norman.
Drilling was started on a relief well within a week of the blowout, but the well burned through the winter of 1962-63 because winter ice in the inlet prevented completion of the relief well until spring.
The blowout wasn't killed until Oct. 23, 1963, more than a year after the blowout began Aug. 22, 1962.
The blowout with the legal history was Middle Ground Shoal State No. 1, Norman said, which blew June 10, 1962, and was killed July 24. Pan American plugged the well but later filed with the state for a discovery royalty certification.
Shell Oil drilled on land immediately adjacent to Pan American's lease, completed a well and subsequently filed for -- and was denied -- a discovery royalty certification. Shell argued that because the Pan American well was plugged, while its own well was completed, that it should receive the royalty reduction.
Shell appealed; the Superior Court found in its favor, but on appeal the Alaska Supreme Court found in favor of Pan American.
Over 5,000 wells
Seamount said 5,570 wells have been drilled on the North Slope in modern times, and "it's been over 10 years since the last blowout" on the Slope, which was at Endicott in 1994.
Foerster said Aurora's recent blowout at Moquawkie "is unusual." The commission is investigating, she said, "and if we find that good oil field practices weren't employed or any of our regulations or stipulations weren't followed then we'll take appropriate action."
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