Characterization of Oil Shale in the Indragiri Hulu Regency, Indonesia, Based on Organic Geochemistry and Petrography

Abstract

Oil shale now becomes important in Indonesia as promising unconventional energy since the conventional oil is decreasing. This study may be classified as a reconnaissance in trying to evaluate oil shale in the Indragiri Hulu Regency, Indonesia that may become source rock of the future unconventional oil. A set of samples comprising thirty-four sediment outcrops have been collected. All samples were screened their richness by analysing their total organic carbon (TOC) and introduced to Rock-Eval pyrolysis apparatus to identify their maturity, type, and also richness. Out of the thirty-four samples, fourteen selected ones were analysed using gas chromatography (GC), sixteen samples for analysis gas chromatography-mass spectrometry (GC-MS), and twenty samples for organic petrography. The sediments could be classified as very good to excellent for their organic richness, in the stage of immature to relatively mature, comprising a mixture between Type I and II kerogens which show oil prone. Petrographic analysis indicates that lamosite contained in the sediments belongs to Rundle type. The Rundle type lamosite that were mainly originated from Pediastrum organisms might indicate that the sediments were deposited in a lacustrine paleoenvironment, i.e. in a specific type of balanced fill basin. It is proven that the studied formation is promising to be source rock for the shale oil that could be exploration target in the near future time.