Evaluation of Oil Potential of Estonian Shales and Biomass Samples Using Rock-Eval Analyzer

Abstract

A possibility for evaluation of oil potential of two Estonian shales and six biomass samples by Rock-Eval data is described. The amount of hydrocarbons volatilized from thermo-labile ingredients of the samples at 300 0 C (S1) is found to increase from 1.1 to 66.3 mg/g in the row: Dictyonema < kukersite < peat < pine sawdust < pine bark < willow < reed ≈ spruce branches. The total oil potential by pyrolysis at 300-650 0 C (S1+S2) increases from 47.4 to 367 mg/g in the row: Dictyonema < peat < reed < pine bark < willow energy crop < spruce needles < pine sawdust < kukersite. An increase in oxygen index decreases the temperature at the pyrolysis maximum rate and S2 but increases S1 of the samples according to relationships approximated to linear regressions.

Characterisation of Pyrolysis Kinetics by Rock-Eval Basic Data

“…The source materials studied were Estonian Ordovician kukersite oil shale and Dictyonema argillite, and six biomass samples -peat, reed, willow, pine bark, pine sawdust and spruce branches, characterised in our previous paper [9].…”

“…In the paper [9] it was shown that the basic data of Rock-Eval were excellent for kukersite and Dictyonema argillite, but gave by 21.3-56.6% underestimated values of the total organic carbon (TOC) when biomass samples were analysed. The discrepancy was explained by the presence of a notable part of acid-soluble organic matter in the "non-geological" samples being extracted before estimation of TOC.…”

“…-free and/or thermolabile hydrocarbons, mg/g sample, evolved at 300 °C S2 -cracked hydrocarbons, mg/g sample, evolved between 300-650 °C TC -total carbon, % from sample TOC -total organic carbon, % from sample T max -temperature for maximum of surface S2, °C OI -oxygen index HI -hydrogen index BI -bitumen index RC -residual carbon E -activation energy, kJ/mol A -frequency factor FID -flame ionisation detector HC -hydrocarbons R -gas constant, 8.314 J/mol β -heating rate, °/min Rock-Eval pyrolysis [1] has been a widely used method in organic geochemistry for examining the oil and gas potential and maturity of different ancient and recent sediment samples [2][3][4][5][6][7][8]. The method was extended to biomass samples in the paper [9]. Besides, a software OPTKIN was developed [10] for description of pyrolysis kinetics using the Rock-Eval measurements.…”

Pyrolysis Kinetics of Oil Shale From Northern Songliao Basin in China

“…It is also used to study kinetics of thermal decomposition of kerogen at pyrolysis. For example, Johannes and Kruusement et al [11] evaluated oil potential and pyrolysis kinetics of two Estonian shales by RE analysis. The first-order kinetics model was proposed to estimate the values of apparent activation energy (E) and frequency factor (A).…”