US EIA Reports Bakken Natural Gas Output Rising as Crude Falls
The US Energy Information Administration (EIA) said November 28 natural gas production from the Bakken field in North Dakota – source of 11% of American crude oil production – continues to increase even as oil production declines.
The ratio of gas production relative to crude production, known as the gas-oil ratio, has been on the rise since 2008, the EIA said, but has been accelerating faster since 2014. In 2008, the ratio was measured at about 750 ft³/barrel of oil; it is now approaching 2mn ft³/barrel.
Total North Dakota crude production, of which 90% comes from the Bakken field's Bakken and Three Forks formations, peaked at about 1.2mn b/d in December 2014, but has since dropped to around 1.07mn b/d.
Natural gas production, however, has continued to rise, and in August this year it reached a record 1.94bn ft³/day – the energy equivalent of more than 330,000 b/d of oil.
“In tight oil formations like the Bakken and Three Forks – which have low permeability – the gas-oil ratio tends to increase only gradually over an extended period of time before reaching a certain point, at which it then increases significantly,” the EIA says in its Today in Energy report for November 28. “As producers extract hydrocarbons from a rock formation, the pressure in the formation eventually falls below the point at which natural gas naturally separates from the gas-saturated crude oil – a threshold known as the bubble point. More oil relative to natural gas tends to be produced during the initial phases of production, after which natural gas production can increase once pressure in the formation reaches the bubble point.”
In past years, infrastructure in the Bakken region was insufficient to take all of the associated gas production to market, which meant that 35% of that gas was flared. In 2014, however, the state’s Industrial Commission mandated new targets to limit flaring to 10% by 2020, and since then the amount of gas flared has fallen to about 200mn ft³/day from more than 350mn ft³/day, a reduction of about 40%.