ABSTRACT

Recent compilation and publication of data by the U.S. Department of Energy and West Virginia University on the Devonian shale production in the Cottageville field of West Virginia have made this a good shale-study area.

A preliminary study utilizing a new unconventional exploration technique has been made based on the available data. The technique is an attempt to reconstruct depositional structural conditions which are thought to control development of the natural-compaction-fracture reservoir.

The depositional highs should have the coarser, less compactible material deposited whereas the depositional lows should have received the finer, more compactible materials. Minimum compaction on the depositional highs and maximum compaction in the depositional lows should result in maximum compaction fractures on the flanks of the depositional highs.

Production from the shale occurs on present-day structural noses with about 250 ft (75 m) of regional dip across the field. There does not appear to be any direct relation between good producers and present-day shale structure.

Most of the producers, approximately 75%, fall within a 50-ft (15 m) depositional structure interval and 100% of the producers with initial flows of over 500 MCFGD fall within the 50-ft interval. Only 11% of the Cottageville field wells had initial flows of over 500 MCFGD. This indicates the possibility of being more selective in selecting locations and substantially increasing the chances of making a good well. The high natural open flows and largest accumulated production seem to be associated with the flanks of the depositional structure.

The preliminary study indicates the utilization of the unconventional technique can substantially improve Devonian shale natural-fracture-reservoir prediction, improve definition of productive limits, and demonstrate the possibility of selectively drilling tests with current economic potential.

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