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15 Fall 2015 Proceedings www.uscg.mil/proceedings language. The American Petroleum Institute (API) devel- oped API gravity or "degree API," which is accepted around the world as the key specifc gravity measure. Specifcally, degree API is a measure of how heavy or light petroleum is when compared to water (which has a specifc gravity of 1). The higher the degree API, the lower the specifc gravity of the oil, relative to water. Oil with a high-degree API is lighter than water, and will foat. Oil with an API number less than 10 has a high specifc New Oil Unconventional oil felds and plays can encompass any pro- gression of tighter, less porous, less permeable rock that requires well treatment to yield hydrocarbons. At one end of the spectrum are the shale oil plays that have been the targets of industry activity. The most common approach used is to drill a large number of wells with horizontal laterals extending from vertical well bores and employ multiple stages of hydraulic fracturing to expand native fracture zones enough to enable hydrocarbon movement. Because the rock structure is very tight, produc- ers can only coax smaller molecules from the subsurface, usually yielding a much lighter production stream than that of WTI. The Bakken formation in the Williston Basin is a prime example. Elsewhere, and especially in the Eagle Ford trend, shale or mud rock formations can yield "black" oil that more closely resembles WTI. The Statistics The U.S. Energy Information Administration recently released its report on the top 100 oil and gas felds in the U.S. Since 2009, approximately 14.2 billion barrels of additional proved oil reserves have been discovered in the U.S. The majority of this comes from the Eagle Ford trend in Texas. 1 In 2013, an estimated 238 million barrels were produced from the Eagleville feld in the Eagle Ford shale play. 2 However, the rapid growth in domestic oil output, espe- cially the lighter "Bakken" type of production, has proved challenging given substantial infrastructure constraints to connect new felds to markets and costs associated with remedies. 3 At the other end of the unconventional oil spectrum are the heavy, dense, often high- sulfur oil accumulations frequently extracted using mining techniques. The most impor- tant source of heavier unconventional oil for North America is Canada's oil sands in the far north of Alberta Province, where companies use steam-assisted production that loosens oil from the sandy matrix that allows the oil to fow to well bores for collection. Sulfur must be removed from this heavy "bitumen," and lighter petroleum products are added. This produces diluted bitumen, or "dilbit," for pipe- line transport. Light, Medium, Heavy The range of oil, from Bakken to bitumen, is classified according to specific gravity and other features so producers, customers, reg- ulators, and the public can share a common U.S. Crude Oil Production Priced at the main trading point — Cushing, Oklahoma. Authors' analysis based on U.S. Energy Information Administration data. Degree API Specifc Gravity Weight (lb/US gal) (kg/m 3 ) 8 1.014 8.448 1012 9 1.007 8.388 1005 10 1.000 8.328 998 15 0.966 8.044 964 20 0.934 7.778 932 25 0.904 7.529 902 30 0.876 7.296 874 35 0.850 7.076 848 40 0.825 6.870 823 45 0.802 6.675 800 50 0.780 6.490 778 55 0.759 6.316 757 58 0.747 6.216 745 Degree API for Crude Oil