Maturity mass fraction

Fig. 7. Cross plots of calculated vitrinite reflectance equivalent biomarker maturity (Ro Ts) and light hydrocarbon maturity (Schaefer Ro) effectively indicates that almost all oils are mixtures in the true sense with a range of maturities of charge being present together in the trap. Only the flagged oils (red dots) may represent single maturity point charges, but even here that is doubtful. A mass fraction maturity concept better describes the maturity of an oil.

Compound specific stable isotope analysis using gas chromatography combined with an isotope ratio mass spectrometer - GC-IRMS (see also Chapter 7) - is now a mature analytical technique in environmental science and technology, especially in the area of contaminant source attribution and in assessing the biodegradation of contaminants.108 Several studies have focused on 13C/12C, 180/160 and 170/160 isotope ratio measurements for volatile organic and metalor-ganic compounds to study isotope fractionation effects and to identify contamination in the environment.109... 

Sulfur compounds in the gas oil fractions from two bitumens (Athabasca oil sand and Cold Lake deposit)> a heavy oil (Lloydminster) from Cretaceous reservoirs along the western Canada sedimentary basin, and a Cretaceous oil from a deep reservoir that may be mature (Medicine River) are investigated. The gas oil distillates were separated to concentrates of different hydrocarbon types on a liquid adsorption chromatographic column. The aromatic hydrocarbon types with their associated sulfur compounds were resolved by gas chromatographic simulated distillation and then by gas solid chromatography. Some sulfur compounds were further characterized by mass spectrometry. The predominant sulfur compounds in these fractions are alkyl-substituted benzo- and dibenzothiophenes with short side chains which have few dominant isomers. 

In view of this unsettled state and the uncertainties of interpretation due to lack of understanding of LEED intensities, only a fraction of published material can be reviewed here. The LEED approach to gas adsorption has matured rapidly in the last few years, and therefore there is considerable unevenness of quality in the published literature. In referring to original papers a reader should bear in mind the state of the art at the time of publication. Other important criteria for judgment are whether a mass spectrometer was used to monitor the gas phase, and whether adequate steps were taken to assure a clean surface before adsorption was initiated. Much of the available LEED literature on gas adsorption is summarized in Tables I and II. Most work has been done on W and Ni, though increasing attention is now being paid to Cu, Mo, Pt, Pd, Al, Fe and other metals. 

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