Larry Bell North East Arizona Energy Services Company nea-esco@hughes.net Dear Mr. Bell: Thank you for your 2/14 email concerning information on the Bakken Formation. In April 2008, the U.S. Geological Survey (USGS) completed a geologic study of the U.S. portion of the Bakken Formation. This study culminated in an assessment with an estimate of 3.0 to 4.3 billion barrels of undiscovered, technically recoverable oil in the Bakken Formation, and a mean estimate of 3.65 billion barrels. This mean estimate is a 25-fold increase over the previous USGS estimate, in 1995, of 151 million barrels of undiscovered, technically recoverable oil in the Bakken Formation. Oil has been produced from the Bakken Formation for several decades and, as of 2007, cumulative oil production from the Bakken Formation totaled about 205 million barrels. You can find the USGS assessment of undiscovered technically recoverable oil and gas resources in the Bakken Formation on our website at http://energy.usgs.gov/. The oil in the Bakken Formation has been naturally heated enough through deep burial to be "mature" and create oil. The problem in the past with the Bakken was that the shale was too impermeable to produce enough oil through a traditional vertical borehole in use at the time. Recently, two technological advances, horizontal drilling and hydraulic fracturing, have been combined to allow economic production of oil from the Bakken. This has opened up a new potential resource that oil companies are exploring. Thank you for your interest in the USGS information on the Bakken Formation. IF we can be of further assistance, please let us know. Donna ****************************************************************** Donna M. Read Energy Program Assistant U.S. Geological Survey 12201 Sunrise Valley Drive 915-A National Center Reston, VA 20192 email: gd-energypubs@usgs.gov Fax: 703-648-5464 Energy website: energy.usgs.gov