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Geology of Southern Utica Easier to Explore, Execs Say
PITTSBURGH -- The geological makeup of the southern Utica shale play in eastern Ohio explains why energy companies drilling there are experiencing higher rates of production than in the northern sections of the play.
Much of it has to do with geological pressure and the porosity of two rock formations -- the Point Pleasant and the Utica -- often collectively referred to as the Utica shale, explains Jeff Ventura, president and CEO of Range Resources.
"The reservoir quality is much better in the Point Pleasant than it is in the Utica," Ventura told the Hart Energy DUG East conference June 4. "The northern third of the play is more about the Utica than it is the Point Pleasant."
The hydrocarbons in the Utica shale are less prolific as those found in the Point Pleasant, a stratum of rock that rests just below the Utica, Ventura said, as he pointed to a map that details a cross section of the play as one moves north.
As one heads north, the Point Pleasant formation becomes scattered and thin in places such as Columbiana, Mahoning and Trumbull counties, not nearly as hearty as in Harrison, Monroe or Noble counties to the south, he said.
"If you consider the southern third, it's more about the Point Pleasant, and it's where the better wells are," Ventura reported. The middle region of the play, generally considered northern Harrison and Carroll counties, is essentially a transitional tier of the play.
What makes the southern play even more appealing is that the Utica serves as a type of hard "cap" over the Point Pleasant. This in turn results in additional geological pressure that helps force hydrocarbons to the surface.
"We're real excited about it," Ventura said. Range Resources, the largest leaseholder in the western Pennsylvania Marcellus shale with more than one million acres under contract, is preparing to drill its first Utica well soon.
Still, there's much to learn about the Utica, noted D. Randall Wright, president of Wright & Co., who was part of a panel discussion at the conference. Moreover, drillers are becoming more efficient as they benefit from others’ experience in shale development, a practice that's aided by improved technology.
That means it's likely that rig counts across the Utica and Marcellus shale plays will decrease, but productivity per well will probably increase, he said.
"It's the advancement of science and technology, and the implementation of different drilling techniques," Wright said. The first generation of Marcellus wells, for example, turned out solid production numbers, but the second generation of wells is performing much better because of advances in technology as well as a better statistical understanding of the play.
Second-generation wells are much more targeted because advanced geo-steering capability has enabled companies to more precisely direct drill bits to more productive reservoirs within the rock.
Also, these wells are drilled with much longer laterals, he reports. In the early exploration of the Marcellus, some horizontal wells were drilled with laterals less than 3,000 feet long. Today, companies are drilling horizontal legs on average between 5,000 and 7,000 feet in length.
Although the recovery percentage from shale reservoirs is on average lower than conventional reservoirs, technology has closed the gap substantially, Wright noted.
"You're used to seeing recovery factors of 60%, 65%, 70% of original gas in place from conventional reservoirs," he said.
As drilling technology and hydraulic fracturing techniques improve, it's plausible that shale recovery could soon command 40% to 60% of total reserves. "One thing that's difficult in the shale is to calculate the volume of the original gas supply."
This same pattern is likely to repeat itself in eastern Ohio, Wright said.
"There are future generations to come," he noted, that are likely to benefit from a new package of statistical analysis.
Copyright 2014 The Business Journal, Youngstown, Ohio.
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