Geology of Hawks Nest-Gilboa Field, East-Central West Virginia
The Hawks Nest-Gilboa gas field produces from the Ravencliff sandstone along a northeast to southwest trend, which is approximately 4 mi wide and 18 mi long. The field was discovered in 1975 by the drilling of the Tipco 1 Vickers well, which was completed for a natural open flow of 2,000 mcf.
A study of the Ravencliff sandstone (Upper Mississippian) by analysis of electric logs, drill cuttings, and full bore cores indicates repetitive cycles of basal conglomerates and sandstones fining upward to a siltstone. This cycle of deposition is interpreted as a fluvial-channel system feeding into a deltaic environment. The channel flowed from the northeast to the southwest with sediment sources to the north and northwest. The eastern margin of the channel is an abrupt contact between the Ravencliff and red beds of the Mauch Chunk Group, but the western boundary is gradational.
The trapping mechanism for the Ravencliff is a combination structural and stratigraphic trap formed by the Ravencliff's abrupt eastern contact with the Mauch Chunk red beds; gas is present updip along the flanks and nose of the Mann Mountain anticline with water downdip to the west. The overlying Pride shale provides both a seal and a source for the hydrocarbons.
The Hawks Nest-Gilboa field contains over 100 producing wells, with ultimate recoverable reserves of 33 bcf. Integration of core and sample data with log analysis and mapping techniques led to an understanding of the deposition of the Ravencliff sandstone and the effective development of the field.
AAPG Search and Discovery Article #91031©1988 AAPG Eastern Section, Charleston, West Virginia, 13-16 September 1988.