Heterogeneity of the Hydrocarbon Distribution in Tertiary Sediments of North-East Sarawak

There are tremendous spatial and temporal variability exists within the sedimentary rock types of the Belait (Early-Mid Miocene) and Lambir (Mid-Miocene) Formations in North Eastern Sarawak. With the current renewed interest in oil and gas exploration in this part of Malaysia, evaluating the distributions of hydrocarbon resources in both Formations will be of valuable interests for the industry.

The IR spectra from both both Formations both recorded presences of aliphatics and aromatic components within the studied samples. TOC analysis for both Formations recorded that majority of the Belait Formations samples possess much higher percentage of organic carbon contents retained then the Lambir Formations. When compared to the E4/E6 values, it can be observed that the high E4/E6 values give rise to more aromatics components and low E4/E6 values showing strong presence of aliphatic peaks in the spectra. Positive relationship on both median pore sizes with the E4/E6 values as well as the E4/E6 values with the samples porosity while contrary with the Belait Formation shales.

Variability in these patterns discussed indicates that there are differences in the quality of hydrocarbon between the Formations. This is attributed to litho-facies differences, source and possibly varying degrees of biodegradation of the hydrocarbon resources. This study reemphasizes the importance of FTIR in current emerging trends in hydrocarbon research.