Kerogen maturation and incipient graphitization of hydrocarbon source rocks in the Arkoma Basin, Oklahoma and Arkansas: a combined petrographic and Raman spectrometric study

Dispersed kerogen of the Woodford-Chattanooga and Atoka Formations from the subsurface of the Arkoma Basin show a wide range of thermal maturities (0.38 to 6.1% R-o) indicating thermal conditions ranging from diagenesis to incipient rock metamorphism. Raman spectral analysis reveals systematic changes of both The first- and second-order spectrum with increasing thermal maturity. These changes include a pronounced increase in the D/O peak height ratio accompanied by a narrowing of the D peak, a gradual decrease in the D/O peak width ratio, and a shift of both peaks toward higher wave numbers. Second-order Raman peaks, though less intensive, also show systematic peak shifting as a function of R-o. These empirical results underscore the high potential of Raman spectrometry as a fast and reliable geothermometer of mature to supermature hydrocarbon source rocks, and as an indicator of thermal maturity levels within the anchizone. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.