Geochemical characteristics of oils from the Sirikit Oilfield, Phisanulok Basin, Thailand

Abstract

Twelve oils from the Sirikit field of the Phisanulok Basin, Thailand, have been examined to determine the nature of their source materials, depositional environment, relative maturity and extent of biodegradation. The geochemical analyses performed in this study suggested that all of the oils were derived from similar types of organic source matter consisting of a mixture of bacterial, algal and higher plant material. The sterane contents of the oils were relatively low and conventional maturity parameters based on sterane ratios suggested the oils were relatively immature. Extensive strike/slip faults in the Phisanulok Basin may have led to rapid burial of the sediments during deposition preventing these ratios from having attained their equilibrium ratios.