Pantheon & Gas Cap27 Jul 2023 16:21
Reproduced courtesy of GeodesRock and AlaskaGeoPhys on Flight’s Discord channel
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**Article. "Prudhoe gas sales in 2020s may be well-timed for aging field"**
**Surprise discovery**
Prudhoe Bay’s story is a tale of the sometimes capricious chemistry of geology, engineering and money.
From the first, a dark day-after-Christmas 1967, when natural gas blew from a wildcat well at a lonesome drill site near a frozen Arctic inlet called Prudhoe Bay, the industry knew it found something special.
When the crew ignited it, the gas jet flared 50 feet despite a 30-mile-an-hour wind, according to one account.
The well had punctured Prudhoe’s gas cap. This was a surprise. The well was targeting the Lisburne formation roughly 1,000 feet deeper than Prudhoe, though a secondary target was Prudhoe’s Ivishak sandstone. (The Lisburne field officially was discovered in 1969 and started production in 1982.)
A confirmation well prompted the Prudhoe discovery announcement in March 1968, and soon came an estimate of what that reservoir a mile-and-a-half underground could yield: a phenomenal 9.6 billion barrels of oil and 26 trillion cubic feet of gas.
Even before production began in June 1977, teams of oil company engineers, geologists, geophysicists and others were analyzing the reservoir with the focus of a grandmaster studying a chessboard. The reservoir held 25 billion barrels, but no oil field surrenders every drop. The 1977 estimate of 9.6 billion barrels produced would be an outstanding result. Coaxing any extra beyond that total would be a sweet bonus.
Today, the Prudhoe Bay producers — mainly ConocoPhillips, ExxonMobil and BP (now Hilcorp) — think they’ll ultimately get around 14 billion barrels of oil and other hydrocarbon liquids from the field. They’ve produced more than 12 billion barrels so far.
Besides gas cycling, pumping water into the field and using miscible injectant, they credit the extra oil to more wells spaced closer together, horizontal drilling and other drilling advances, among other factors. Gas cycling makes them all more robust.
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