Under Explored Plays in the Northwest Appalachian Basin

Under Explored Plays in the Northwest Appalachian BasinOpportunities for the Independent?
A presentation to SIPES on March 25, 2004.
Abstract: The first drilling for petroleum in the Appalachian Basin occurred in the late 1800''s with Drakes well in Pennsylvania. Since then thousands of wells have been drilled with the majority of exploration has being less then 5,000 feet deep. Reservoirs have been discovered and produced from the Cretaceous, Devonian, Silurian, Ordovician, Cambrian and others. Reservoir types range from carbonates to clastics, generally deposited in shallow marine conditions. Traps are either structural, stratigraphic or fracture/solution enhanced stratigraphic traps. Source rocks are believed to be primarily Silurian and Ordovician in age.
Early exploration focused on Cretaceous, Devonian and Ordovician traps, some of which were enhanced by nitro fracturing. In the 1970-1980''s the Silurian Medina - Clinton sandstones have been extensively drilled for gas. More recently the Ordovician Trenton - Black River carbonates with enhanced solution porosity are being targeted. In addition, the Upper Cambrian Rose Run Sandstones of the Knox Formation are being drilled in Ohio. These are erosional remnants which are trapped along the Knox Unconformity. Other Cambrian aged reservoirs exist as structural traps and stratigraphic pinch outs along regional highs.  Discovered reserve estimates for the basin are 36 Tcf. of gas produced and 8 Tcf. of gas remaining to be produced. Estimates for produced oil are uncertain but field sizes in excess of 500 MMBO exist in the basin. The USGS estimated total undiscovered reserves are 70 Tcf. of gas, 872 MMBNGL and 54 MMBO.
In the northwest portion of the Appalachian Basin (Ohio and western Pennsylvania) only about 70 wells have penetrated the base of the Cambrian section. This compares to thousands of wells which have been drilled to at least the Ordovician. Similarly, there are hundreds of producing fields in the post Ordovician section and around thirty producing Cambro Ordovician fields. One explanation given for this situation is the difficulty in identifying deeper traps and the expected poor quality of the reservoirs. Both of these problems are real but the use of modern exploration and production tools coupled with higher product prices should produce commercially attractive prospects.
In the Cambro-Ordovician section three under explored plays exist. These are the Lower Cambrian aged Mount Simon sandstone trapped in pinch outs or draped across basement highs, Cambrian Knox et. al. sandstones trapped in anticlines or stratigraphic traps and Ordovician aged Trenton - Black River limestones in fracture enhanced structural/stratigraphic traps. Each of these plays is proven in the basin. The Mount Simon has production in western Pennsylvania, the Knox in eastern Ohio and the Trenton - Black River from at least Ontario, Canada to West Virginia.
The USGS has not quantified the undiscovered field sizes for the Mount Simon. For the Knox the USGS estimates a median field size of 8 Bcf up to a maximum of 250 Bcf. For the Trenton - Black River they estimate a median field size of 18 Bcf up to a maximum of 750 Bcf. With average drilling depths between 5,000 and 10,000 feet, gas values above $5 per thousand and the relatively low level of exploration drilling, these reservoirs at least appear to be interesting candidates for exploration by independent operators.
Biography: Daniel Bendig has a MSc. degree from the University of London in Stratigraphy, a MA degree from SUNY at Buffalo in Geology and a BS degree from the Ohio State University in Physics. He is a member of the AAPG, DPA Certified Petroleum Geologist #5649, a member of the HGS (2) and SIPES #2972. His career has been as a geophysicist working in Houston, Ponca City, Jakarta, London and Aberdeen. He has experience working on projects in South East Asia, Irian Jaya, North Africa, West Africa, North Sea, West of Shetland, Venezuela and Trinidad. Assignments ranged from new venture evaluations to equity determinations. He is now an independent working on the petroleum potential of the Appalachian Basin.