ABSTRACT: Role of resinite in hydrocarbon generation from Indonesian coals
Atkinson, Chris D.1, and Andrew R. Livsey2
(1) ARCO British Ltd, Guildford, Surrey, England
(2) PT Robertson Utama Indonesia, Jakarta, Indonesia
The liptinite maceral "resinite" is an important constituent of Tertiary coals throughout Western Indonesia. It is thought to be derived from the abundant resins of the tropical lowland trees of the Diptocarp family. Samples from the Miocene of the Kutei Basin (Kalimantan) and the Oligocene of the Ardjuna Basin (offshore Java) have been examined in order to assess the role of resinite in oil generation from coals. In both the Kutei and Ardjuna basins, resinite is particularly abundant within the vitrinite-rich coals and shales of the lower and upper delta plain.
These resinites are hydrogen rich, highly extractable and thermally labile. Pyrolysis-gas chromatography data indicate that the resinite products are not paraffinic and consequently they are not thought to be a volumetrically-significant contributor to the terrestrially-derived oils seen in these basins. However, they do appear to contribute cyclic hydrocarbons and several important biomarkers which are evident in many of these oils.
The thermal lability of the resinite is supported by the presence of secondary products in low maturity coals (VR=0.35-0.45%) and confirmed by artificial maturation experiments. These products may influence later oil migration by increasing the saturation of micropores/fractures within the coal and thus facilitating expulsion of later generated oil from the other liptinitic macerals.
The abundance of resinite in many tropical Tertiary coals implies caution should be exercised when estimating source potential. A combination of pyrolysis-gas chromatography and high resolution visual kerogen microscopy gives the most reliable estimate of source potential from these types of coaly deposits.
AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia