GEOLOGY OF THE MARCELLUS AND UTICA SHALES IN OHIO

Recent drilling and completion technological advances have created a paradigm shift in the oil and gas industry – what once were mainly thought of as only source rocks are now viewed as reservoirs. Thanks to advances in multi-stage fracture stimulation and horizontal drilling the Devonian Marcellus Shale and the Ordovician Point Pleasant Formation-Utica Shale interval in Ohio are now the target “reservoirs” of a large lease and drilling “boom”.

The recent Marcellus drilling started in Ohio in 2006 following successful wells in Pennsylvania. The Marcellus is at best only about 60-feet thick in southeastern Ohio (eastern-most edges of Belmont and Jefferson Counties) and quickly thins to 10-feet as one heads west (Harrison County). Thus, while thousands of Marcellus wells were being permitted in Pennsylvania, Ohio only saw 30 wells drilled in this unit thru 2009. However, starting in 2010 the leasing frenzy of Pennsylvania spilled over to Ohio and approximately 60 Marcellus wells were permitted and huge swaths of land are being pursued.

While the Marcellus play has matured in Pennsylvania, another organic-rich shale play has been slowly gaining momentum in the eastern U.S. Operators have had success using these new technologies within the Utica Shale in New York and along the St. Lawrence River lowlands of Quebec. While the Utica may be as much as 800-feet thick or more in these regions, over much of Ohio it is 200 to 350 feet thick – still plenty to justify pursuit of this target over about two-thirds of the state. Also, within much of Ohio the Utica is directly underlain by, and in part in an equivalent facies arrangement with, the Point Pleasant Formation, which is comprised of interbedded organic-rich limestones and black shales. Also, due largely to less ultimate burial depth, analyses indicate much of Ohio’s Utica interval may be oil prone. In fact, a number of historical wells have encountered large shows, and some have even produced oil from this interval. The areal size and thickness of the Utica-Point Pleasant interval, along with the prospect of oil production could make this one of the largest shale plays in North America. Drilling is underway now in Ohio and western Pennsylvania to test the productivity.