Determination of Sterane and Triterpane in the Tamsagbulag Oilfield

Crude oils representing four different holes from the Tamsagbulag oilfield were analyzed by gas chromatography-mass spectrometry (GC/MS) spectroscopy. Fifty-two biomarker compounds, 34 pentacyclic triterpanes and 18 steranes were identified and semi-quantitatively determined by selective ion monitoring (SIM) chromatography. Depending on the oil source, the variation in the pentacyclic triterpanes distribution is more significant than the variation in the sterane distribution. It is said that pregnane and honopregnane originated during the period of very salty sedimentary accumulation in the condition of diagenesis.