In 2012, the U.S. Geological Survey (USGS) published its first assessment of the oil and gas resource potential for the Utica Shale and the Appalachian Basin, and the numbers were impressive. But this July it revised upward its estimate of the Utica’s technically recoverable reserves—to match those of the Marcellus Shale.
The Ordovician Shale has distinctive thermal windows for oil to dry gas generation. The source rock in the basin is immature to the west, giving a distinctive oil window, and gradually transitions into more overmature dry gas to the east.
The 2012 USGS study said the total technically recoverable reserves of the Utica Shale were approximately 45 trillion cubic feet equivalent (Tcfe): 38 Tcf of natural gas, 940 million barrels (MMbbl) of oil and 208 MMbbl of NGLs. This estimate placed the Utica’s technically recoverable reserves at just over one-tenth the size of its neighboring formation, the Marcellus, which has approximately 354 Tcf of proved natural gas reserves, according to Energy Information Administration (EIA) estimates made in 2014.
Through analysis of more recent well results from operators, and in a new study, the Appalachian Oil and Natural Gas Research Consortium, a leg of West Virginia University’s National Research Center for Coal and Energy, said the Utica resource ranks above most unconventional gas basins in North America.
The study found that the shale’s technically recoverable natural gas estimates top 780 Tcf and 940 MMbbl of oil. This places the size of the Utica in line with the Marcellus, proving that the Appalachian Basin is one of the largest unconventional gas resources in the world.
The Utica was initially developed as an oil play with operators focused in the oil window of central and western Ohio. After realizing that the oil window did not yield desirable results, they shifted to target the wet gas fairway of Carroll, Columbiana and Tuscarawas counties, where activity remained focused through 2014.
When the price of oil declined in mid-2014, many operators updated their strategies to begin delineating the relatively less costly dry gas window, which has remained largely untouched. The core area of focus now falls within Harrison, Belmont, Monroe and Noble counties in southern Ohio.
Operators that have acreage and constructed pads in southwestern Pennsylvania and northern West Virginia are now targeting the underlying Utica on their pre-existing Marcellus pads. Further movement and delineation of the Utica’s dry gas potential is expected, as Antero Resources recently announced its first exploration well to be drilled in Tyler County, West Virginia, in 2015. If the well proves successful, Antero will leverage its 180,000-acre position in West Virginia to target both the Marcellus and the Utica.
Chevron Corp. drilled the first Utica well in West Virginia in early 2014, followed by Magnum Hunter Resources, which drilled the play’s second West Virginia well in mid-2014 on its Stewart Winland pad, which also holds three producing Marcellus wells. Magnum Hunter placed its Utica well online in September 2014, and it tested at a peak rate of 46.5 million cubic feet per day (MMcf/d) of dry gas. The production stream from this well consisted of 98% methane and 1.5% ethane.
As a result of these new estimates for technically recoverable reserves and the shift to more dry gas production, Stratas Advisors has updated its geologic productivity map for the Utica. Historically, the sweet spots and core acreage were found within the wet gas window in the northern counties of Ohio. Stratas Advisors believes that the new wave of Utica production will consist mainly of dry gas in West Virginia and southwestern Pennsylvania, and it will be drilled on current Marcellus pads. The increase in technically recoverable reserves pushes the Appalachian Basin into the top tier of unconventional gas resources worldwide.
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