Subdivision of Lower Portion of Huron Member of Ohio Shale, Kanawha and Boone Counties, West Virginia, and Applications to Gas Production

Frank P. Caramanica

Current work funded by the Gas Research Institute indicates that, in Kanawha and Boone Counties, West Virginia, most gas wells completed in the Devonian shales produce from the lower part of the Upper Devonian Huron Member of the Ohio Shale.

The lower Huron can be subdivided into as many as five distinct, black organic shale and gray silty shale and siltstone assemblages, both types being traceable by use of wireline logs across the two-county area of study.

Discrete assemblages of black shale emplacement in this part of the Appalachian basin can be discerned and are mappable using log data from wells that penetrate the lower Huron section. Black shale isolith maps across the two-county area show discrete elongate trends of black shale, thinning predominantly from northeast to southwest.

These elongate black shale minima are interpreted herein as sites where newly deposited, black organic mud substrates were scoured by the action of relatively high-velocity turbidite plumes entering this part of the basin from shallower regions toward the east and northeast. Turbidite-transported muds and silts were then laid in the newly scoured areas in close vertical and lateral contact with the surrounding black muds.

This interfingering of organic black shales with the gray silty shales and siltstones is significant to gas production from the Devonian shales in that the interbedded nature of these rocks provides a mechanism whereby gas generated and held by absorption in the black shales can migrate into the more porous and permeable gray shales and siltstones, hence from there into a fracture system or a well bore.

AAPG Search and Discovery Article #91031©1988 AAPG Eastern Section, Charleston, West Virginia, 13-16 September 1988.