Note for readers: going forward, PTTC's prior Appalachian and Midwest regions are now functioning as a combined Eastern Region. This combination will realize synergies through working with AAPG's Eastern Section and other groups.

Only a small percent of all the wells drilled in the Appalachian Basin go below 7,500 feet. There are, however, significant sediments below that depth. Although production is very mature in the formations that are the historical mainstays, many of those deeper horizons lie untested, forming an attractive exploration target. This, combined with the nature of the players also changing to more aggressive exploration-oriented companies, means there is now strong activity in the mature Appalachian Basin. Unconventional resources are one target with industry bringing what they have learned from the Barnett Shale and other shale gas plays to bear on the Basin's Devonian-age shales.

The Marcellus Shale in Pennsylvania is one example. Range Resources-Appalachia LLC (Range) has invested some $200 million on drilling, coring, seismic and science to apply to the Marcellus. By the end of 2007, Range will have completed some 15 horizontal wells in Washington County, southwest of Pittsburgh. They are moving rapidly along the learning curve and expect to soon move from exploration to the development and exploitation phase. At 6,100 - 6,500 feet, the Marcellus is somewhat shallower than the Barnett Shale, which means costs should be lower once they are optimized.

The Huron Shale, also relatively shallow at about 6,000 feet, is another unconventional target. Cabot Oil & Gas (Cabot) is involved in a horizontal drilling program for the Huron in an area between Huntington and Charleston, WV. Cabot has drilled five horizontals and plans to drill more. They note good success, with fracturing going well and drilling being repeatable. It's that repeatability that becomes important as one moves to the exploitation phase in a shale gas play.

Expectations are for some wells to produce up to 1 Mmcfd. Range and Equitable Resources are involved in a joint venture in the Nora Field in Virginia. Most wells there are vertical, but there is one horizontal.

No discussion of exploration in the Appalachian Basin would be complete without mention of the Trenton-Black River. Development may have slowed somewhat—being a deep reservoir, it is costly and drilling results are not uniform. Nevertheless, significant potential remains. A few years ago with support from DOE's National Energy Technology Laboratory (NETL), the Trenton-Black River Appalachian Basin Exploration Consortium was formed to merge the resources, data and technical expertise of 17 exploration companies and West Virginia University. The Consortium's report, Geologic Play Book of Trenton-Black River Exploration in the Appalachian Basin, incorporates regional geologic, geochemical and geophysical data into a model that can be used for exploiting the Trenton-Black River. The report can be obtained on CD through NETL (www.netl.doe.gov
/publications/descriptions.html).

The boom in activity is not limited to the unconventional arena—activity is also higher for the traditional formations/plays. With stronger prices smaller operators have increased their drilling, if they can get rigs. The edges of existing fields are being pushed and there is some pure wildcatting. Companies that once left the basin are now returning in one form or another.

Supporting this increased activity, state agencies in the Appalachian Basin have worked hard to make O&G data readily accessible. Some of the systems/data available are described in a prior Tech Connections column (July 2007 in The American Oil & Gas Reporter available online at www.pttc.org/aogr_
columns/aogrcojuly07.
htm) and in a prior PTTC Network News (www.pttc.org/newsletter/
2qtr2007/v13n2p8.htm). A GIS-based system, originally developed by PTTC's Appalachian Region and now maintained by the Appalachian Natural Gas and Oil Research Consortium at West Virginia University, provides one a "quick look" at activity in the Trenton-Black River, coalbed methane and horizontal well arenas.

the Appalachian Basin, Carbonate Reservoirs, and Structural Geology and Structural Gas Plays.