Abstract

Development success across a very diverse set of resource plays in the U.S. prompts the question: what should we regard as unconventional anymore? Commercial success at scales of national significance (>1 BCFE/D now or forecasted within a few years) has been achieved in at least 7 shale plays, 7 tight gas sand plays, and 2 coalbed natural gas plays. Collectively these categories, including hybrid oil/gas plays, will dominate US gas production in the coming decades, according to most analysts. Yet many fundamental questions remain about EUR and production mechanisms, and the experimenting continues wherever hydrocarbon-charged, tight fracable lithologies can be leased and drilled. Tight high-TOC carbonates, fractured cherts and porcelainites, silt-stones, and other targets are being pursued in many U.S. basins. If sustained high oil and gas prices occur (a big “if!”), operators will also pursue “alternative unconventionals” – hydrates, heavy oils, and dissolved methane in deep aquifers. The rapid evolution of drilling and completion technologies since 2000 will probably be complemented in the next 10 years by technologies that address “secondary” and “tertiary” oil and gas recovery from the spectrum of resource plays. The effectiveness advanced-recovery approaches is a poorly known variable in resource-play assessment efforts. Societal issues, such as controversies over frac fluid migration, possible mineral trespass by hydraulic fracturing, surface disturbance, access to federal lands, and water usage/water disposal, will continue to slow development of unconventional resources in some areas.