Since 2005, production of oil from the Bakken formation of North Dakota has increased substantially, and the region now supplies about 1.5% of global oil output. This study presents a first engineering-based assessment of the energy intensity of Bakken crude oil production and computes the resulting NER (net energy return) from Bakken hydrocarbon production. The energy required to drill, produce, and process Bakken oil and gas is estimated for over 7000 wells using open-source drilling and production assessment models. The largest energy uses are from drilling and processing of produced fluids (crude/water emulsions and gas). Fluid lifting and injection and embodied energy are also important energy needs. Median energy consumption equals approximate to 3.4% of net crude and gas energy content, while mean energy consumption equals approximate to 3.9% of hydrocarbon energy. The median NER is 29.3 MJ/MJ. The inter-quartile range is 24.3-35.7 MJ/MJ, while the 5%-95% range is 13.3-52.0 MJ/MJ. NERs have declined in recent years, with a decline in median NER of 23% between 2010 and 2014. Results are most sensitive to modeled estimated ultimate recovery, and embodied energy. (C) 2015 Elsevier Ltd. All rights reserved.