GEOCHEMISTY OF BICYCLIC ALKANES IN SEDIMENTS, COAL AND CRUDE OILS

By using GC-MS to analyze the extracts of source rocks, coal and crude oil samplesformed in different sedimentary environments in China, New Zealand and Australia, twenty-two compounds of five types of bicyclic alkanes have been dis covered in the samples. Thispaper makes an exposition of stereochemical structure, abundance and distributive features ofthese compounds and their relation to sedimentary environments and thermal evolution. Furt-thermore, it demonstrates how the abundance ratios of bicyclic alkanes to steranes and ter-panes, drimane to homodramane and the relative abundance of C_(15),C_(16),C_(12)-C_(14) series of bicyclic-alkane compounds can be used to judge and determine types of oil and gas forming environ-ments (the depositive environments of source rocks from which the oil and gas wereformed), characteristics of source rocks and degree of maturation.     

GEOCHEMISTRY OF PETROLEUM MIGRATION DURING THE FORMATION OF KARAMAY OIL FIELD

The phenomena of geochemical migration during the formation of the Karamay Oil Field have been revealed by correlating the compositions of non-hydrocarbon, asphaltene, steranes and terpanes from between oils and rocks. The study on abnormal compaction observed in a deep well, which is located between the source area and the oil field, and the corresponding depletion of hydrocarbons further clarifies the conditions of the migration of oil and gas. Results show that the necessary condition for the formation of this giant oil field is a long distance of lateral migration of oil and gas followed by a redistribution along Ka.-Ur. large fault before accumulation in a large uplift.     

Fingerprinting Marine Pollutant Hydrocarbons by Computerized Gas Chromatography-Mass Spectrometry

Abstract

A series of petroleum hydrocarbons of geochemical significance (biological markers) such as C₂₀-C₄₀ acyclic isoprenoids and C₂₇-steranes and triterpanes are proposed as passive tags for the characterization of oils in the marine environment.

Mass-fragmentography of samples IS used to make evident there series of components without complex enrichment treatments. The rational choice of the characteristic ions 1s discussed and both molecular and stereoisomeric profiles are considered for identification purposes. Furthermore. computerized gas chromatography-mass spectrometry permits multiple fingerprinting from the same GC run. Hence rapid and effective comparisons between bamples and long term storagr of the results for future examination can be carried out. Differences between oils from the same geographic area and correlations of highly weathered samples are exemplified.