The drilling and oilfield services industry should be pleased with the first assessment of oil and gas reserves in the Utica Shale play by the US Geological Survey, which indicates that extraction of the reserves would take approximately 110,000 wells in the gas window and another 17,500 wells in the oil window.
To date, about 144 horizontal wells have been drilled in Ohio, which is where the richest reserves are located. By comparison, about 26,000 wells have been drilled so far in the overlying Marcellus Shale formation, which is generally considered to be about two to three years ahead of the Utica in terms of development.
The “sweet spot” of what the USGS refers to in oil assessment lies almost entirely in Ohio and covers about 2.1 million acres in the east-central part of that Midwestern state.
The Utica Shale contains about 38 trillion cubic feet (tcf) of undiscovered, technically recoverable natural gas, according to the report. The Utica has a mean of 940 million barrels of unconventional oil resources and a mean of 208 million barrels of unconventional natural gas liquids.
The Utica Shale lies beneath the Marcellus Shale, and both are part of the Appalachian Basin, which is the longest-producing petroleum province in the United States. The USGS Utica assessment covers areas in Maryland, New York, Ohio, Pennsylvania, Virginia, and West Virginia.
The Marcellus Shale, at 84 tcf of natural gas, is the largest unconventional gas basin USGS has assessed.
“Understanding our domestic oil and gas resource potential is important, which is why we assess emerging plays like the Utica, as well as areas that have been in production for some time,” said Brenda Pierce, USGS Energy Resources Program Coordinator. “Publicly available information about undiscovered oil and gas resources can aid policy makers and resource managers, and inform the debate about resource development.”
Some shale rock formations, like the Utica and Marcellus, can be source rocks – those formations from which hydrocarbons, such as oil and gas, originate. Conventional oil and gas resources gradually migrate away from the source rock into other formations and traps, whereas continuous resources, such as shale oil and shale gas, remain trapped within the original source rock.
These new estimates are for technically recoverable oil and gas resources, which are those quantities of oil and gas producible using currently available technology and industry practices, regardless of economic or accessibility considerations.
This USGS assessment is an estimate of continuous oil, gas, and natural gas liquid accumulations in the Upper Ordovician Utica Shale of the Appalachian Basin. The estimate of undiscovered oil ranges from 590 million barrels to 1.39 billion barrels (95% to 5% probability, respectively), natural gas ranges from 21 to 61 tcf (95% to 5% probability, respectively), and the estimate of natural gas liquids ranges from 4 to 16 million barrels (95% to 5% probability, respectively).
USGS is the only provider of publicly available estimates of undiscovered technically recoverable oil and gas resources of onshore lands and offshore state waters. The USGS Utica Shale assessment was undertaken as part of a nationwide project assessing domestic petroleum basins using standardized methodology and protocol.