The Marcellus shale play, already one of the most prolific unconventional regions in the world, could hold more than $90 billion more in hydrocarbon riches and is positioned to account for nearly 25% of total US shale gas output, according to consultancy Wood Mackenzie.
Low gas prices have slowed drilling in the Marcellus over the past several years. But gas remains a cornerstone of US efforts to curb greenhouse emissions, and the Marcellus will be producing for years to come, WoodMac said.
The consultancy has raised its forecast of 2020 output from 14 billion cubic feet equivalent per day 20 Bcfed.
It expects the top 20 operators - including companies like Range Resources, Chesapeake Energy and Cabot Oil & Gas - to drill 25,000 wells through to 2035, spending nearly $110 billion in the process.
The spending level could rise or fall depending on how far operators can push increasing efficiencies. High-volume completions and longer laterals have helped maximise production, but have also increased the need for proppant and water.
Operators in the "Southwest Rich Gas" sub-play have increased their water use from four million gallons to 10 million gallons per well, and their sand use from about one million pounds to 13 million pounds per well over the last four years, according to WoodMac.
Proppant usage increased by 58% between 2012 and 2013 alone, it added. Drilling and completion costs now range from about $6 million to $9 million across the 16 sub-plays designated by WoddMac.
These increases have offset many efficiency gains. However, "well results are improving, with estimated ultimate recovery in the top areas increasing by approximately 10% since 2013", WoodMac said.
"Although rig counts have fallen across the Marcellus since early 2012, we can see that improved efficiency and a renewed focus on the play's core sub-plays have led to on-going growth."
The "Susquehanna Core" sub-play has so far produced the top-performing dry gas wells in the Lower 48, but WoodMac believes "there is limited running room and that most near-term growth will come from the liquids-rich sub-plays in south-west Pennsylvania and West Virginia".
The Marcellus spans over 30 million acres across four states.