Drillers Set Sights on Shale Reserve Deeper Than the Marcellus
Pittsburgh Tribune Review
22 February 2011
By Kim Leonard
Another underground strip of shale in Pennsylvania, much deeper than
the Marcellus formation, is drawing attention from natural-gas drillers.
Utica shale has potential, like Marcellus, to become a major fuel
resource. The rock layer stretches far beyond the edges of the
Marcellus, covering most of Pennsylvania, New York and West Virginia,
along with eastern Ohio and parts of other states.
"A number of companies are taking a careful look at this shale, and in
eastern Ohio there's been a fair amount of leasing" for well
development, Penn State University geosciences professor Terry Engelder
said Monday.
Consol Energy Inc. drilled a Utica shale well last year in Belmont
County, Ohio, that generated 1.5 million cubic feet of gas over 24
hours -- impressive for a well where production wasn't stimulated,
spokeswoman Laurel Ziemba said.
"It's actually higher than the rate from any of our vertical Marcellus
wells" where production was triggered, she said. Cecil-based Consol
plans to spend $35 million this year to drill about six
exploratory Utica wells.
Range Resources Corp., a Fort Worth company with Appalachian offices in
Cecil, is drilling in the Utica formation. Range drilled the first
commercial horizontal well in the Utica formation in
Southwest Pennsylvania, spokesman Matt Pitzarella said.
Chevron Corp. completed its $4.3 billion acquisition of Atlas Energy
Inc. of Moon last week, giving the energy giant access to 623,000 acres
of Utica shale resources. The company isn't specifying
its plans for Utica shale, Chevron spokesman Nate Calvert said.
The Marcellus shale formation that sparked a rush of drillers to
Pennsylvania and other Appalachian states averages 7,000 feet deep, and
the older, thicker Utica layer runs 2,000 or more feet below
that. The black Utica shale, 500 feet thick in places, dates 440
million to 460 million years.
Some geologists estimate the Marcellus formation has 50 trillion cubic
feet of recoverable gas, enough to supply the East Coast for 50 years.
Although it hasn't been studied enough to determine its potential,
Utica shale has shown the ability to support commercial gas production,
a report in website geology.com said, and depending on how
much of it might yield fuel, it could be larger than any known gas
field.
Gas producers could drill down and then horizontally and inject
high-pressured water, sand and chemicals to fracture the shale and free
gas deposits, just as they do in Marcellus fields, Engelder
said.
The additional depth isn't a hindrance, he said. "There's the
Haynesville formation in Louisiana, where drillers are going as deep as
13,000 feet using the same technology," Engelder said.
Rock formations in the Appalachian basin tend to be thickest in the
east and thinner toward the west, the geology.com report said. The
Utica is about 7,000 feet below the Marcellus in central
Pennsylvania, but less than 3,000 feet below it in eastern Ohio. In
Western Pennsylvania, the Utica layer runs 11,000 to 12,000
feet deep.
Although the two gas-producing shale layers overlap, production
companies could focus on different regions.
That's because certain parts of each shale formation will yield more
fuel, based largely on temperature and pressure histories, Engelder
said. His analogy: Shale that remained cooler, like a piece of
underdone toast that won't melt butter, won't yield much gas, nor will
a too-hot formation that burned off its gas, like
blackened toast.
Rock that reaches 190 degrees Fahrenheit generates oil and some gas, he
said. The top heat for creating, and not destroying, gas is 480 degrees.
Much of the Utica shale in that ideal pressure and temperature range
stretches from the northwest Pennsylvania town of Titusville, where an
oil boom began 150 years ago, to Columbus, Ohio,
Engelder said.
Tom Murphy, co-director of Penn State's Marcellus Center for Outreach
and Research, said Utica gas could have a higher British thermal unit,
or BTU, content than Marcellus gas, making it
more marketable.
"The southeastern part of Ohio right now is being explored for Utica
shale gas," Murphy said, and some work is occurring in West Virginia.
Landowners who lease mineral rights typically strike
deals for producers to drill "all the way down" past the Marcellus to
other layers of rock, he said.
Range Resources plans to drill a few more wells this year in the Utica
and Upper Devonian shale layer, which is above the Marcellus. Gas
producers potentially could drill multiple layers of
wells in the future, all from the same spot, Pitzarella said.
"The Utica and Upper Devonian may combine to be as large as the
Marcellus" in terms of recoverable gas, he said.
Kim Leonard can be reached at kleonard@tribweb.com or 412-380-5606.