A quantitative fluorescence technique for evaluating thermal maturity: Instrumentation and examples

Abstract

Fluorescence microscopy is useful not only for identifying most of the oil-prone organic matter (macerals) in sedimentary rocks and coals but also for assessing their thermal maturities (ranks). This report introduces a violet-light excitation system which induces more than one order of magnitude stronger fluorescence intensity that the commonly used UV-light excitation system. The red/green quotient from violet-light excited fluorescence, Q v , of sporinite can be easily measured using this system. Several examples using coal and cuttings samples are presented to demonstrate the use of this technique for evaluating the thermal maturities of coals and sedimentary rocks. From the results of our studies we conclude that: 1. (1) Violet-light excited fluorescence from sporinites can be routinely measured to assess thermal maturity. 2. (2) Spectral (Quantitative) fluorescence technique is useful for evaluating thermal maturity when samples are poorly polished or deficient in vitrinite. 3. (3) Visual (Strew-mounted) kerogen slides can not be used for fluorescence measurements unless a non-fluorescent mounting medium is used.