C-GC-MS and its application to crude oil analysis

The Gas Chromatograph linked to a Mass Spectrometer with computerised data acquisition capability (C-GC-MS) makes for a very versatile and powerful analytical tool. The important function of the GC-MS in petroleum exploration and production studies is its ability to detect BIOMARKERS. What are biomarkers? They are organic compounds whose carbon skeleton give an unambiguous link with a known natural or biological product. Examples are isoprenoids, triterpanes, steranes, sterols etc. In other words they may be described as ‘chemical fossils’. Their thermal stability in oils and sediments (source-rocks) make them very useful in oil to source rock correlation studies or determination of the number of oil pools present in an area. A study using GC-MS data on nine ‘oil stained’ rock samples from S E Asia and the Bahamas will be highlighted as an example to illustrate the usefulness of C-GC-MS in the recognition of petroleum and determination of its source and maturity.