Utica shale bad news for coal

THE Utica shale holds 20 times more recoverable gas than previously thought, a two-year geological study by the Appalachian oil and natural Gas Research Consortium has found.

Anthony Barich

The study, led by West Virginia University, shows that the Utica play contains technically recoverable resources of 782 trillion cubic feet of gas and 1.96 billion barrels of oil.

In a 2012 study, the US Geological Survey estimated that technically recoverable resources in the Utica – the volume that can be extracted from the reservoir using existing technology – were 38Tcf and an additional 940MMbbl of oil.

It rubs more salt into the wounds of coal after the EIA confirmed last week that gas had surpassed it as the leading source of the country’s electricity, driven in party by production from the Marcellus Shale and other plays.

Yet this new study – sponsored by Anadarko, Chevron, CNX, ConocoPhillips, Devon, EnerVest, EOG Resources, EQT, Hess, Range Resources, Seneca Resources, Shell, Southwestern Energy and Tracker Resources – suggests there is more to come underneath the Marcellus.

The National Energy Technology Laboratory’s Strategic Centre for Natural gas and Oil also funded the study.

The Marcellus is the US’ largest shale oil and gas play and second largest in the world at present. In 2013, a US Energy Information Administration study reported that Marcellus Shale operators produced 2.86Tcf of gas.

Data from Utica shale play book study, which was presented at a workshop on Tuesday in Canonsburg, Pennsylvania, revealed that original gas-in-place – the amount of hydrocarbon store in the reservoir prior to production – is approximately 3192Tcf and original oil-in-place is about 82.903 billion barrels of oil.

It is expected that given current technology, the play-wide oil recovery factor will be about 3% and the gas recovery factor will be about 28% in the sweet spot areas.

However, the study also noted that core studies of samples from Ohio – the state which had the largest source of production data – determined that the organic-rich Utica Shale had TOC (total organic carbon) up to 3.5% and an average carbonate content of 25%.

This, the study said, meant the clay content was probably in the 70% range, which is very high – “perhaps too high for the rock to be hydraulically fractured effectively”

The study also noted that petrographic and SEM (scanning electron microscopy) analyses performed on Utica/Point Pleasant rocks in Ohio, New York and Pennsylvania indicated the existence “little to no matrix porosity”

“Porosity, where it does exist, is found in the organic matter of these reservoir rocks,” the study said.

“If this holds true in the current producing area, the only pores that are likely to be contributing much to hydrocarbon flow are the organic pores that formed during maturation.

“This makes the Utica very different from other liquids-producing plays, such as the Eagle Ford and the Bakken, which have significant matrix porosity components.”

Still, the consortium’s director Douglas Patchen, a renowned expert on the Appalachian Basin, said the revised resource numbers were “impressive, comparable to the numbers for the more established Marcellus Shale play, and a little surprising based on our Utica estimates of just a year ago which were lower”

“This is why we continued to work on the resource estimates after the project officially ended a year ago,” he added.

“The more wells that are drilled, the more the play area may expand, and another year of production from the wells enables researchers to make better estimates.”

The majority of the Utica Shale play lies beneath the Marcellus Shale play. The interval between the two plays – the space between the Marcellus and the deeper Utica – ranges from 4000ft in Ohio to greater than 6500ft in West Virginia.

The drilling depth of the Utica ranges from less than 4000ft in Ohio to more than 12,000ft in West Virginia, which is more than 3.2km below the surface.

The Appalachian oil and natural Gas Research Consortium is a partnership of 15 industry members, four state geological surveys, two universities, one consulting company, and one national lab.

They include the WVU National Research Centre for Coal and Energy, Washington University, the Kentucky Geological Survey, the Ohio Geological Survey, the Pennsylvania Geological Survey, the West Virginia Geological and Economic Survey, the US Geological Survey, Smith Stratigraphic and the US Department of Energy National Energy Technology Laboratory.

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