Action is ongoing in the late Ordovician-age Utica shale play in the northeastern United States, despite the drilling pullback in shale plays overall owing to the global downturn in crude oil prices.
The Utica sits beneath the geologically younger, highly productive Marcellus shale of Devonian age. It is the primary source rock for many conventional hydrocarbon-bearing reservoirs throughout the Appalachian Basin.
The source rock component of the geographically extensive Utica underlies parts of Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, West Virginia and Virginia - and trends northward into Canada.
Areas of dry gas, natural gas liquids and oil windows occur in the widespread formation.
Take your pick.
Shell opted for dry gas not long ago when it stepped out of the main drilling area into Tioga County, Pa., where it drilled a couple of successful wells more than 100 miles northeast of the closest horizontal Utica producer.
The Gee and Neal discovery wells were drilled to the deep Utica-Point Pleasant formation, tallying initial flowback rates between 11 and 26 MMscf of natural gas per day.
This heralded a significant new field discovery in the deep formation, which Shell announced in September 2014.
Today, the company has seven wells online in this play extension, with two more set to come on soon. Vertical depths range between 10,000 and 12,000 feet.
"Reservoir quality is exceptional over a net pay range of 250 to 500 feet, exhibiting well-connected kerogen porosity-permeability networks and high reservoir pressures," said Christopher Gonsalves, Tioga area manager at Shell Appalachia.
The Utica-Point Pleasant relationship is tricky to nail down, presenting a challenge to geoscientists who want a more refined definition - it can be highly interpretive as to what is Point Pleasant and what is Utica.
The Point Pleasant, composed of interbedded organic-rich limestones and black shales, is more distinct to the west, where it sources the bulk of the liquids-rich play in Ohio.
Whatever the case, the new play extension is economically productive. Gonsalves commented that appraisal results to date have been in line with the initial discovery wells, and breakeven gas prices for development are expected to be less than $3/MMcf.
Existing pipeline infrastructure plays an important role in the economics.
The discovery was the result of considerable study and evaluation on the part of the Shell team's members.
"Regional play-based exploration led to the Utica-Point Pleasant discovery in Tioga County, with the integration of detailed well synthetics from Shell's southwest Pennsylvania exploratory well and new regional 2-D seismic in 2011," Gonsalves said.
"Reinterpretation of legacy well logs revealed inconsistencies with published basin architecture and evolution concepts that suggested the Utica depositional sweetspot was limited to southeast Ohio," he noted.
"Integration of seismic interpretation, consistent log analyses and detailed core and outcrop descriptions confirmed a subtle, fault-bounded Utica age depocenter coincident with basement structures in Tioga that were reactivated during the Middle Ordovician Taconic Orogeny," he continued.
Ultimately the Shell team arrived at an interpretation that suggested the Utica Basin extended from southeast Ohio into northeast Pennsylvania, and rock properties converge in a sweetspot - where Shell commands an impressive leasehold position of more than 350,000 net acres.
"Additional appraisal will continue to delineate the extent of commercial hydrocarbons," he said.