The main objective of this work was to study the effect of the kerogen isolation procedures on maturity parameters of organic matter using optical microscopes. This work represents the results of the Organic Matter Concentration Working Group (OMCWG) of the International Committee for Coal and Organic Petrology (ICCP) during the years 2008 and 2009. Four samples have been analysed covering a range of maturity (low and moderate) and terrestrial and marine geological settings. The analyses comprise random vitrinite reflectance measured on both kerogen concentrate and whole rock mounts and fluorescence spectra taken on alginite. Eighteen participants from twelve laboratories from all over the world performed the analyses. Samples of continental settings contained enough vitrinite for participants to record around 50 measurements whereas fewer readings were taken on samples from marine setting. The scatter of results was also larger in the samples of marine origin. Similar vitrinite reflectance values were in general recorded in the whole rock and in the kerogen concentrate. The small deviations of the trend cannot be attributed to the acid treatment involved in kerogen isolation but to reasons related to components identification or to the difficulty to achieve a good polish of samples with high mineral matter content. In samples difficult to polish, vitrinite reflectance was measured on whole rock tended to be lower. The presence or absence of rock fabric affected the selection of the vitrinite population for measurement and this also had an influence in the average value reported and in the scatter of the results. Slightly lower standard deviations were reported for the analyses run on kerogen concentrates. Considering the spectral fluorescence results, it was observed that the λmax presents a shift to higher wavelengths in the kerogen concentrate sample in comparison to the whole-rock sample, thus revealing an influence of preparation methods (acid treatment) on fluorescence properties.
|Number of pages||12|
|Journal||International Journal of Coal Geology|
|State||Published - Dec 1 2010|
Bibliographical noteFunding Information:
The following persons and institutions are thanked as sample providers: A.G. Borrego from INCAR-CSIC (OMC1) C.V. Araujo from Petrobras (OMC2), J.C.M. García-Ramos from Jurassic Museum of Asturias, MUJA (OMC3) and L.V. Duarte from the University of Coimbra (OMC4). The contribution of A.D. de Oliveira (LAFO) and A.J. Sant'Anna (Petrobras) to sample preparation and of Petrobras research center for providing the organic geochemistry analysis is gratefully acknowledged. The financial support of the Palynofacies & Organic Facies Laboratory (LAFO) from Federal University of Rio de Janeiro (UFRJ)-Brazil has allowed the performance of the OMCWG exercises. CSIC-CNPq is thanked for a bilateral Spain-Brazil project CSIC-2007BR0011 and CNPq-490416/2007-1 which has favored the planning of the exercises and the discussion of the results.
- Dispersed organic matter
- Isolation of organic matter
- Kerogen concentrate
- Spectral fluorescence
- Vitrinite reflectance
ASJC Scopus subject areas
- Fuel Technology
- Economic Geology