Thermal maturity assessment of marine source rocks integrating Raman spectroscopy, organic geochemistry and petroleum systems modeling

Abstract

A core sample set, comprising twenty-eight carbonaceous mudrocks from ten exploration wells was analysed by standard organic geochemical methods (programmed pyrolysis, elemental analysis) and a novel Raman spectroscopic technique. The kerogen of the studied rocks is classified as amorphous marine, sulfur-rich, oil-prone organic matter with predominantly algal precursor material. The sample set covers a wide range of thermal maturation from premature to late mature. Hydrogen index, Tmax and atomic H/C ratios vary from 52 to 708 mg HC/g rock, from 426 to 488 °C, and from 0.58 to 1.35, respectively. Raman spectral features, expressed as Raman band separation (RBS), correlate with geochemical maturity parameters and with results from basin modeling. The combined use of independent maturity parameters, like programmed pyrolysis, elemental analysis and Raman spectroscopy, improves the calibration of a regional basin model in the Eastern Arabian Basin, where direct maturity measurements from vitrinite reflectance are deficient.