Appalachian Fields Drive Rising US Gas Output
Production from two major Appalachian shale gas plays, the Marcellus and the deeper Utica shales, is driving an overall increase in US natural gas production, the US Energy Information Administration (EIA) says in its Today in Energy report for December 4.
Through August of this year, total Appalachian gas production had increased by more than 14bn ft3/day since 2012, offsetting declining production from virtually every other major gas basin in the US. Overall Marcellus and Utica production averaged 23.8bn ft3/day through August this year, the EIA said, up from 22.1bn ft3/day in 2016 and just 7.8bn ft3/day in 2012. Total gross US gas production currently hovers just under 90bn ft3/day, up from a little over 80bn ft3/day at the start of 2012.
The increase in Appalachian production, the EIA says, can be traced largely to dramatically more productive gas drilling, with the average monthly production per rig for new wells increasing by some 10.8mn ft3/day since January 2012, from about 3mn ft3/day to just over 14mn ft3/day. By comparison, new production per rig from the Haynesville shale play in Texas has increased by less than 3mn ft3/day since 2012.
The EIA attributes the increased Appalachian productivity to efficiency improvements in horizontal drilling and multi-stage hydraulic fracking, which includes faster drilling, longer laterals and better targeting of wells.
“For example, in West Virginia, the average lateral length per well has increased from about 2,500 feet in 2007 to more than 7,000 feet in 2016,” the EIA says. “Some operators have recorded lateral lengths as long as 15,000 feet in Appalachia and 19,000 feet in the Utica. Along with longer horizontal drilling, the days it takes for completion have decreased from about 30 days in 2011 to 7 days in 2015.”
The Marcellus shale play covers more than 245,000 km² from New York in the north to Kentucky and Tennessee in the south. Wells in the eastern part of the play are mostly dry gas, while most of the liquids-rich wells are found in the western regions.
The Utica play, meanwhile, incorporates two stacked geological units, the Utica and the Point Pleasant formations, both of which are found below the Marcellus horizon. The play covers about 155,000 km2 in Ohio, West Virginia, Pennsylvania and New York, and has seen about 1,800 wells drilled as of November this year. By comparison, more than 11,300 wells have been drilled in the Marcellus, the EIA says.