PETROGRAPHIC CHARACTERISTICS AND PETROLEUM POTENTIAL OF OIL SHALE FROM NA HONG BASIN, CHIANG MAI, THAILAND
Keywords:
Oil shale, organic petrology, maceral, petroleum source rockAbstract
The Na Hong basin is a small basin in the west of Chiang Mai Province, northern Thailand. Twenty-one oil shale samples were collected from Huai Phak La in the Na Hong basin. The aims of this study are petrologically to analyze the organic matter of the oil shale and to determine the oil source potential using geochemistry techniques, including proximate analysis, ultimate analysis, calorific value, and total organic carbon (TOC) analysis. The results of this study show that the organic matter of the oil shale is dominated by the liptinite group which ranges from 10.00–66.50%. The liptinite is composed mainly of lamalginite and liptodetrinite, with minor amounts of telalginite, sporinite, exsudatinite, and resinite. The vitrinite group which ranges from 4.00–40.00% is composed mainly of gelovitrinite, and the inertinite group has a range from 0.00–3.00% of fusinite. Mineral matter ranges from 21.00–80.50% and is composed mainly of clay minerals and quartz. Proximate analysis shows that the moisture content, ash content, volatile matter and fixed carbon content range from 3.26–5.90%, 53.70–78.98%, 15.83–34.52%, and 1.93–21.45%, respectively. Ultimate analysis shows that the carbon content, hydrogen content, sulphur content, and oxygen content range from 10.23–25.61%, 1.81–3.95%, 0.32–8.15%, 7.72– 12.58%, respectively and the nitrogen content is mostly less than 1 %. The calorific values range from 821-3025 kcal/kg and the TOC content ranges from 4.16–22.31 wt%. Oil shale from this basin is the lamosite type. Apparently, the very dark gray and tough sample (sampling number PL1-23) shows a grade with high carbon, hydrogen, and calorific value. The study results indicate that the oil shales in the Na Hong basin show a trend to be good source rocks of Type II/III kerogen.
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