Subsurface stratigraphy and gas production of the Devonian shales in West Virginia
The subsurface Devonian shales are defined as all of the fine clastic rocks between the top of the Onondaga Limestone and the base of the Berea Sandstone. This term is used only in the western one-third of the state where the thickness of these shales ranges from 1000 to 3000 feet. The interval thickens to the east and northeast and facies changes to coarser clastics occur. In north-central West Virginia numerous sandstones and siltstones have replaced much of the shale section, particularly the so-called Brown shales. These shales are actually dark gray to black, organic-rich, generally non-silty shales that yield higher natural radioactivity readings on a gamma-ray log, and low readings on a density log. Sample descriptions, cable-tool drillers' logs, and gamma-ray and density logs are all used to subdivide the Devonian shales into 4 zones: a thick (1100 to 1200 feet) upper sandy, silty, gray, and greenish gray shale; a thinner (300 to 400 feet) zone consisting of two dark to very dark gray shales (the Brown shales of the driller) separated by a thin gray shale; a greenish gray, generally non-silty shal; and the lowermost interval that consists of very dark to black shales, often calcareous near the base. A thin limestone is often noted within the lowest black shale and is usually referred to by drillers as the Tully. Farther to the west and southwest a fifth zone, a younger Brown shale, is present near the top of the Devonian shale sequence in the approximatestratigraphic position of the Cleveland Shale of Ohio. Natural gas has been produced for nearly 50 years from relatively shallow-depth, low-volume wells completed in the Brown shales and adjacent units. Although these wells are marginally economic at current costs, prices, and completion techniques, these shales represent a very large gas resource with less than 10 percent of the calculated gas in place ever produced.
- Research Organization:
- West Virginia Geological and Economic Survey, Morgantown (USA)
- DOE Contract Number:
- EY-76-C-05-5199
- OSTI ID:
- 7294890
- Report Number(s):
- MERC/CR-77/5
- Country of Publication:
- United States
- Language:
- English
Similar Records
Upper Devonian outcrop stratigraphy along Appalachian basin margin in southeastern West Virginia and southwestern Virginia: Implications for hydrocarbon exploration
Petrography of selected Devonian shale core samples from the CGTC No. 20403 and CGSC No. 11940 wells, Lincoln and Jackson Counties, West Virginia
Related Subjects
04 OIL SHALES AND TAR SANDS
BLACK SHALES
STRATIGRAPHY
NATURAL GAS DEPOSITS
EXPLORATION
WEST VIRGINIA
FRACTURES
GAMMA LOGGING
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CENTRAL REGION
ENERGY SOURCES
FAILURES
FOSSIL FUELS
FUELS
GEOLOGIC DEPOSITS
GEOLOGY
NORTH AMERICA
OIL SHALES
RADIOACTIVITY LOGGING
RESOURCES
USA
WELL LOGGING
030200* - Natural Gas- Reserves
Geology
& Exploration
040201 - Oil Shales & Tar Sands- Site Geology- (-1989)