Drilling activity has increased in the northern Appalachians in response to the energy shortage and rising well head oil and gas price. In addition to exploitation of remaining known marginal reserves, exploration for reserves in new areas and new zones characterizes the most recent surge in activity. The entrance of non oil and gas industry into field operations, directly and indirectly, is providing the additional incentive and the competitive climate necessary for the evaluation and discovery of new reserves.
Exploration for reserves in new areas and new zones holds the promise for evaluation of the potential of a Basin less than 35% explored. Initial success is encouraging for the future. Successful wildcatting for hydrocarbon discovery from known producing zones in new areas is expanding the portion of the Basin considered prospective for economic recovery of hydrocarbons. Upper Devonian and Oriskany discoveries east of the region of historic development and exploration in these zones are primary examples that attractive reserve potential remains to be evaluated. Although the Devonian Shales are an "old secondary pay", recent realization of the extent of reserve pay", recent realization of the extent of reserve recoverability and the region prospective for successful exploitation has made this previously ignored section a primary industry and government new zone target. As evaluation is enabled by current activity, other new pay zones can be expected to be defined in the Silurian and Cambro-Ordovician sections, the vast unexplored portion of the Basin.
The geological significance of results of current activity in the northern Appalachians is reviewed.
The purpose of this paper is two fold: first, to provide an overview of the nature of recent oil and gas provide an overview of the nature of recent oil and gas industry activity in the northern part of the Appalachian Basin, and second, by such overview to emphasize the potential of, and need for technique and discovery exploration.
Petroleum engineering exploration for economically Petroleum engineering exploration for economically applicable drilling, completion, and recovery methods is as important as geological exploration for new deposits of economically recoverable hydrocarbons.
"The Appalachian Basin's most encouraging statistics for the first half of 1977 come from Pennsylvania" (1, p. 7). Completions increased by 21 Pennsylvania" (1, p. 7). Completions increased by 21 percent to 482 wells comparing the first half of 1977 percent to 482 wells comparing the first half of 1977 with 1976. Activity in other bounding States of the Northern Appalachian Basin decreased during the same period, and can be categorized as essentially period, and can be categorized as essentially exploitation of known potential reserves. First half 1977 completions in Ohio declined 5 percent to 744 wells, the Silurian Clinton sandstones being the primary target. Activity in West Virginia remained basically steady with 466 wells drilled in the first half, the historic Mississippian Big Injun and Berea, Upper Devonian Benson, and Lower Devonian Chert being the objectives. Completions in New York declined 53 percent to 92 wells, the Lower Devonian Onondaga and Oriskany and Silurian Medina sandstones being exploited.
An overview of Pennsylvania activity is selected to best illustrate the nature of recent industry drilling results in the northern Appalachian Basin. Geological aspects of this activity are highlighted to provide meaningful context to statistics. Exploitation provide meaningful context to statistics. Exploitation of known hydrocarbon reserve potential in productive areas, and exploration for new areas and new zone reserves are differentiated in reviewing shallow formations and then deep formations activity. It is the discovery and recovery of new reserves that will enable future continuation of industry in the region.
Recent industry activity for shallow Mississippian and Upper Devonian sandstone reservoir oil and gas reserves is predominantly field development and extension in the historic western Pennsylvania oil and gas productive region. Limited exploration is evidencing productive region. Limited exploration is evidencing potential for discovery of new gas reserves east of potential for discovery of new gas reserves east of the productive region.