Introduction Evaluation Prospects











The purpose of performing gas chromatography in this evaluation was to geochemically characterize the known Nevada oils and relate these oils to their source rocks.

Crude oils from the four producing oil fields in Nevada, the Blackburn (27 API gravity, 1 degree fahrenheit pour point, and 0.7-1.1 % sulphur) field in Pine Valley, the Grant Canyon (26 API gravity, 10 degree fahrenheit pour point, 0.8 % sulphur), Trap Spring (21-25 API gravity, 0-40 degree fahrenheit pour point, 0.8 % sulphur), and Eagle Springs (26-29 API gravity, 65-80 degrees fahrenheit pour point, 1.7% sulphur) fields from Railroad Valley were collected and analyzed. These crude oils were separated into fractions with liquid chromatography and both the whole oil and saturate fractions were analyzed with gas chromatography using a Varian model 3300 gas chromatograph.

For comparison and correlation, ten representative samples of the Elko and Sheep Pass Formations, Chainman and Pilot Formations, Roberts Mountains and Woodruff Formations, and the Vinini Formation were also analyzed. Many of the samples originally chosen for analysis on geological parameters did not contain enough extractable organic material for chromatographic analysis. A close relationship between pyrolysis S1 yield and total extract recovery was noted. The details of the chromatographic analytical procedures are given in Appendix VI.

The analytical results of the chromatography are shown in Appendix VI. The four whole oil capillary gas chromatographs are displayed together for visual comparison and are followed by individual plots showing both whole oil and oil saturate fraction chromatograms for each oil. These diagrams are followed by whole rock extract chromatograms for the Elko, Sheep Pass, Chainman, Pilot, Roberts Mountains, Woodruff, and Vinini Formations. A table of calculated prystane/phytane, prystane/C17, phytane/C18 and carbon preference index for the whole oil and saturate fractions of the oils, and the whole rock extracts of the outcrop samples is also presented in the appendix. The reader is encouraged to examine this data while reading the interpretations in this section.

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Last modified: 09/12/06