Unconventional Geophysics for Unconventional Plays

Abstract In conventional plays the role of the geophysicist is primarily that of locating and delineating the resource. This is most commonly accomplished through the use of active source seismic exploration. In this classic case it is the responsibility of the geophysicist to identify the structures associated with the trap and migration pathways of the resource. In the last twenty years this role has been expanded through the applicability of direct hydrocarbon indicators where, particularly in the Gulf of Mexico, the resource itself can often be identified using seismic exploration. In the case of unconventional resources neither the trap nor the presence of hydrocarbons are unknowns. The source rock, reservoir and trap are continuous and well defined. As such it would be easy to dismiss the geophysicist's role as diminished to one where his primary responsibilities are secondary concerns, such as hazard avoidance through the location of faults. However, in practice, the role of the unconventional geophysicist is much more complex and multi-dimensional. Access to resource in an unconventional rock is largely controlled by exposure to the rock, i.e. how efficiently it can be hydraulically fractured. The unconventional geophysicist can contribute to the understanding of how to best access the resource by studying the finer scale heterogeneities in the rock which are manifested indirectly through various seismic attributes such as anisotropy and curvature, and directly measured through microseismic monitoring of hydraulic stimulations.