Organic petrography and geochemistry of the prolific source rocks from the Jurassic Najmah and Cretaceous Makhul Formations in Kuwait – Validation and expansion of Raman spectroscopic thermal maturity applications

Abstract Raman spectroscopy has been applied in numerous sedimentary formations to infer thermal maturity of mostly Type-II kerogen in organic-rich mudrocks. Robust correlations have been established between the Raman spectroscopic signal and vitrinite reflectance equivalents (%VRE) of the organic matter. Herein, traditional evaluation methods, organic petrography and geochemistry, were applied in addition to Raman spectroscopy, to study the prolific source rocks of the Najmah and Makhul Formations in Kuwait. The elemental analysis of isolated kerogen provided insight into the kerogen type and likely classified samples from these two formations as kerogen Type II-S. The standard organic petrography maturity and geochemistry parameters were correlated to the spectroscopy derived Raman band separation (RBS) values. This allowed to further validate our previously established thermal maturity correlation (RBS vs %VRE with R2 = 0.80) and generate a new geochemistry-related correlation of RBS vs hydrogen index (HI) with R2 = 0.92.