The United States Geological Survey (USGS) has reevaluated the Bakken Formation that runs through North Dakota and Montana, and the results are record-breaking.
The USGS estimates Bakken to possess 3.0 to 4.3 billion barrels of "undiscovered, technically recoverable" oil and 1.85 Tcf of natural gas. The formation is also estimated to hold 148 million barrels of natural gas liquids.
"This is the largest oil accumulation in the lower 48," said USGS scientist Brenda Pierce. "It is also the largest continuous oil accumulation that we've ever assessed."
Pierce explained that technically recoverable oil is oil that is recoverable with the technology available today. The current technically recoverable oil estimate of the Bakken Formation increased 25 times compared to the 1995 USGS assessment.
Pierce attributed the increase in the 2008 estimate to the advances in technology that have allowed USGS to achieve a more accurate portrait of what is recoverable from the famous formation.
With the help of new geologic models, technical advances in production and drilling, and available industry practices, the USGS believes these "substantially larger" volumes are realistically recoverable. By the end of 2007, 105 million barrels of oil had been recovered from the Bakken Formation.
"Bakken has become a significant production target," said USGS scientist Rich Pilastro. "Bakken has been a challenge for decades … the Bakken has some hidden secrets that we've [been able] to unveil."
USGS based the assessment "on geologic elements of a total petroleum system (TPS) that include (1) source-rock distribution, thickness, organic richness, maturation, petroleum generation and migration; (2) reservoir rock type (conventional or continuous), distribution and quality; and (3) character of traps and time of formation with respect to petroleum generation and migration."
To give some perspective to the Bakken estimates, the USGS states that the next-largest continuous oil accumulation in the United States is the Austin Chalk, which spreads though Texas and Louisiana. The technically recoverable oil estimate for the Austin Chalk is 1.0 billion barrels.
"It is clear that the Bakken formation contains a significant amount of oil -- the question is how much of that oil is recoverable using today's technology?" said North Dakota Senator Byron Dorgan. "To get an answer to this important question, I requested that the U.S. Geological Survey complete this study, which will provide an up-to-date estimate on the amount of technically recoverable oil resources in the Bakken Shale formation."
USGS stated in a press release that the assessment team consisted of a number of petroleum industry companies and independents, universities and other experts that helped develop a geological understanding of the Bakken Formation. These groups provided USGS with critical information and feedback on geological and engineering concepts important to building the geologic and production models used in the assessment.
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