U.S. Geological Survey Open-File Report 03-041
Figure 6

Figure 6.  The N₂ content of North Slope gases as a function of depth, stratigraphic sequence, and the occurrence of samples within known fields or in non-field wells.  The vertical line at 4 mole % N₂ provides a visual reference to distinguish high N₂ content samples from the more frequent low values that are typical of oil field gases.