Published:December 01, 2009
For more than 50 years, the U.S. natural gas industry has been developing unconventional gas reservoirs. Production of natural gas from eastern Devonian Shales and tight gas sands in Texas and in the Rocky Mountain and Midcontinent regions has been the proving ground for many innovations in well drilling, completion, and stimulation. Over the past two decades, successful gas production from coal seams and from shales, such as the Barnett Shale, has led to new drilling and completion technologies. In 2007, unconventional gas production was 9.15 Tcf, accounting for 47% of the U.S. dry gas production, and eight of the top ten U.S. gas plays were producing from unconventional reservoirs. Unconventional gas reservoirs, led by shale, are expected to provide the majority of the U.S. gas supply growth in coming decades. Clearly, many basins worldwide contain large volumes of unconventional gas resources that have not been assessed. As conventional oil and gas reservoirs are depleted in those basins, inevitably, unconventional gas reservoirs will be developed. The key to successful development will be the proper application of existing technologies and the continued development of new technologies.
Over the past 5 years, a team of engineers and geoscientists in the Crisman Institute at Texas A&M University have worked to capture the critical geologic and engineering properties of unconventional gas reservoir in 25 North American basins. The primary objectives of this research are to (1) understand the gas resource distributions and the best technologies for unconventional gas recovery and economics, and (2) assess the volumes of unconventional gas in basins, worldwide, beginning with North America, using the concept that resources are log-normally distributed (resource triangle). Our evaluations of North American basins indicate that the Technically Recoverable Resource of unconventional gas in any basin will be approximately 5-10 times greater than the ultimate recovery (cumulative production plus proved reserves) from all conventional oil and gas reservoirs in the same basin.
Our research shows that historic unconventional gas drilling and production have been impacted strongly by technology and gas prices. The oil and gas industry should continue developing new technology to access unconventional gas reservoirs in diverse settings. The Research Partnership to Secure Energy for America (RPSEA) is supporting the development of new technology to optimize recovery of unconventional gas resources in the U.S. In coming decades, this technology that is being developed in the U.S. will be deployed worldwide to increase natural gas production from unconventional reservoirs and to contribute needed energy supplies.