All analyses are performed to NPD standards or, where appropriate, NBS or other international standards ( for example SMOW and SLAP and NBS21, NBS22 are standards routinely run during our stable isotope analyses).

Biomarker analyses are performed in SIR mode once the oil has been treated with geokleen*. The NPD oil is used as a standard alongside GHG's own internal standard.

Isotope analyses for oils and fractions are performed with NBS22 used as the daily standard. Internal accuracy of the instrument is +/- 0.005 per mil. Accuracy for repeatability with NBS22 is +/- 0.05 per mil.

Reproducibility for carbon isotope analyses of gases is +/- 0.15 per mil.

Gases are prepared off-line so at least 0.5% of gaseous component is required for accurate analysis.

Reservoir Oil Fingerprinting.

This analysis does not have an international reference standard. The success of the analysis depends on the reproducibility of the repeat analysis of the same oil. Differences in the interparaffin peaks are used for comparing and contrasting oils and hence minimising these differences between repeated runs of the same oil is important.

* Geokleen is a silicalite based product manufactured by GHG and is used to remove n-alkanes from an oil in order to pre-concentrate the biomarker prior to GC-MS analysis.

© Copyright GHGeoChem Ltd 2004