Hydrocarbon Migration and Retention in Fine-Grained Clastic Successions: Conventional Approaches to Evaluating Unconventional Resources

Rene Jonk
ExxonMobil

Hydrocarbon production from so-called “unconventional” reservoirs has been rapidly increasing in the last decade. Exploration for these resources, particularly within the continental U.S., was carried out differently from conventional accumulations, relying instead on identification of enigmatic sweet spots whose profitability was mainly controlled by advances in drilling and stimulation technology. We find, however, that standard play element assessment techniques aid in the delineation of profitable unconventional accumulations much in the same way as is required for assessing conventional resources. An important distinction is that a more fundamental understanding of the subtleties of hydrocarbon saturation and adsorption is required. In this study, we demonstrate that finegrained, clay-rich stratigraphic successions (“shales”) are heterogeneous and contain all aspects of plays (reservoirs, seals, sources, traps, and migration) that can be analyzed using conventional methods. Furthermore, these elements may be mapped at an appropriate scale to allow assessment on a basin, play and perhaps even prospect scale.

AAPG Search and Discovery Article #90185 © AAPG Geoscience Technology Workshop, Revisiting Reservoir Quality Issues in Unconventional and Conventional Resources, Austin, Texas, November 12-13, 2013