The Role of Minerals in Petroleum Generation, a Laboratory Perspective

Abstract

Abstract

Petroleum is naturally generated by the pyrolysis of sedimentary organic matter; the process which can be simulated in the laboratory using analytical pyrolysis techniques. The aim of this study was to investigate the roles of minerals in petroleum generation through effects of minerals interactions during analytical pyrolysis and evaluate whether they qualitatively affecting pyroproducts. Both pyrolysis temperature (750°C-1000°C) and heating duration (time, 8 -15 sec) were set as kinetic parameters. The investigation of degradation behavior and structural analysis of asphaltene is indispensable for understanding and improving performance characteristics. Asphaltene which was isolated from bitumen using n-hexane as an extracting solvent was a compound of interest through which silica (SiO₂) and pyrite (FeS₂) minerals were adsorbed on. Pyrolysis gas chromatography mass spectrometry (Py-GC/MS) was used as an influential tool for separation and identification of pyrolysate. The pyroproducts were dominated by a series of n-alkanes and n-alkenes up to C32 showing the high aliphatic character of asphaltene fractions isolated from Kurdistan bitumen. The main aromatic hydrocarbons identified in the pyrolysate are alkyl benzene, naphthalene and methylnaphthalene. This study proved that; minerals are qualitatively affecting pyrolysate. Silica observed to have insignificant influences on the generation of pyroproducts when compared to pyrite which showed significant catalytic effects on the pyrolysis of asphaltene. The catalytic activity of pyrite was proved by the production of methane of up to 10 times higher than that for silica though methane is also formed by normal thermal cracking processes due to free radical mechanism. Pyrite also observed to enhance aliphatic hydrocarbons with prolonged heating. After pyrolysis, the residues were studied by Raman spectroscopy for identification of solid carbonaceous organic matters present in asphaltene. Due to extensive structural similarities between coal and asphaltene, a coal sample was used for correlation studies.

Key words: Pyrolysis, Asphaltene, Petroleum, Pyrolysis gas chromatography mass spectrometry (Py-GC/MS), Raman spectroscopy, Pyrite, Silica gel, Pyrolysate/Pyroproducts

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016