Shale Gas Exploration

The initial steps in exploring the petroleum potential of a black shale is to establish the gas saturations in the shale and the composition of the shale. Gas saturations can be measured from well logs and from cores. The shale also needs to have high porosity in order to have the storage capacity to serve as an effective reservoir rock, just as with a conventional reservoir. These examples of early exploration wells drilled in New York by MegaEnergy show two nearby wells with very different gas saturations. The well on the left (Henninger-1) has high gas saturations as expressed by the neutron-density log cross-over. The well on the right (Fischel-1) is wet in the Marcellus Shale, due to faulting which expanded the stratigraphic interval and allowed the gas to escape from the shale.

Seismic attribute analysis can be used to identify areas of over-pressuring in the Marcellus Shale and high grade drilling locations. These techniques could also be applied to the Goldwyer Shale. An example of the increase in amplitude versus offset (AVO) on seismic gathers from an area in an over-pressured Marcellus Shale interval is shown below.