Analysis of three shale gas fields illustrates the importance of basement structure in developing fracture permeability within the thick Devonian shales of the Appalachian basin. A porous fracture facies within the organic rich lower Huron shale member of the Ohio Shale relates to a regional stress field created by differential shortening of overlying sedimentary section across the lower Huron detachment zone during the Alleghanian deformation. Greater permeability (commercial) occurs near the outer margin of tectonic shortening. Linear trends of wells with abnormally high final open flows relate to linear trends of highly fractured shale. These trends were probably caused by unique stress fields created along flexures in the shale above basement fault zones.

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