Possible Continuous-Type (Unconventional) Gas Accumulation in Lower Silurian "Clinton" Sands, Medina Group, and the Tuscarora Sandstone in the Appalachian Basin: A Progress Report of 1995 project activities

Robert T. Ryder, Kerry L. Aggen, Robert D. Hettinger, Ben E. Law, John J. Miller, Vito F. Nuccio, William J. Perry, Jr., Stephen E. Prensky, John R. SanFilipo, and Craig J. Wandrey

Open-File Report 96-42

OBJECTIVES AND RESEARCH STRATEGY

The main objective of this project is to establish geologic controls and pressure/temperature conditions of the regional Clinton/Medina gas field. From these attributes, we should gain a better understanding of the field and be able to evaluate whether or not it is correctly classified as a continuous-type gas accumulation. Similar controls and conditions will be examined for the Tuscarora Sandstone reservoir and its scattered gas fields to determine the feasibility of extending the continuous-type gas accumulation eastward and deeper into the basin. Additional objectives are: 1) to define the range of gas production per well throughout the accumulation and evaluate the geologic cause(s) of the production variability, in particular, production "sweet spots" in the accumulation, 2) to develop a model for gas generation and entrapment, and 3) to review, and revise if necessary, the methodology for assessing recoverable gas in the accumulation. We anticipate that the Clinton/Medina/Tuscarora(?) example may provide an assessment analog for similar gas accumulations in the United States and the World.

Topics to be addressed in detail include:

1. stratigraphic framework of Clinton/Medina/Tuscarora sandstones across parts of New York, Ohio, Pennsylvania, and West Virginia,
2. comparison of gas-well productivity (initial production and EUR) against variations in reservoir depth, reservoir thickness, and structural setting,
3. structure contour and drilling depth maps of the reservoir interval across the Clinton/Medina/Tuscarora sandstone play area,
4. downdip limits of oil and water production,
5. thermal maturation history of the Clinton/Medina/Tuscarora reservoirs based on conodont alteration indices (CAI) and burial, thermal, and petroleum generation models,
6. geochemistry and isotopic composition of natural gas in the Clinton/Medina/Tuscarora reservoirs and their bearing on the source, thermal maturity, and migration history of the gas,
7. role of fractures on gas productivity and the utility of seismic profiles and(or) geophysical log suites for their detection,
8. variation in formation pressure and temperature across the area of the Clinton/Medina/Tuscarora plays,
9. core and well log analysis to determine the degree of continuity of small-scale lithologically and(or) diagenetically controlled zones of high porosity and permeability in the sandstone reservoirs,
10. compilation of an oil and gas field map for the Clinton/ Medina/Tuscarora reservoirs, and
11. environmental concerns such as land use and brine composition in regions of Clinton/Medina/Tuscarora gas production.

Given the large area involved, with thousands of wells, many of these planned topics of investigation will focus along regional transects oriented normal and parallel to the paleoshoreline and the present-day basin margin. Most of the transects are designed to be long enough so as to accommodate detailed comparisons between the proposed continuous-type gas accumulation of the Clinton/Medina sandstone gas play and adjoining accumulations of the Clinton/Medina sandstone oil/gas and Tuscarora Sandstone gas plays. Substantial computer support is required for storage and manipulation of data files and the construction of digital maps.

Created by the EERT WWW Staff.