Source Rock Evaluation in Petroleum Geology: Standardized Terminology and Integrated Geochemical Criteria

Abstract

Petroleum-system analyses are based on source-rock evaluation, since the interplay of sedimentary organic matter quantity, quality, preservation, and thermal evolution drives hydrocarbon generation, preservation, and expulsion. This review summarises the key terms, analytical parameters, and interpretive criteria used to define organic-rich sedimentary rocks and their petroleum potential. The interrelationships among organic richness, kerogen type, hydrocarbon affinity, generation potential and thermal maturity are highlighted. This paper combines the major descriptive and analytical tools widely used in source-rock studies, such as total organic carbon (TOC) and Rock-Eval pyrolysis parameters (HI, OI, PP, PI to Ro, Tmax, TAI, and SCI). It reviews in detail the classification of sedimentary organic matter components into sapropelic and humic groups, the distinction between kerogen Types I-IV, and the transformation of organic matter through diagenesis, catagenesis, and metagenesis. An integrated framework, rather than isolated parameters, is critical for reliable source-rock interpretation; this argument is considered here. This review offers a more coherent foundation for source–rock evaluation by structuring these indicators into a unified evaluative workflow and outlining their strengths and weaknesses (with respect to evaluating play potential) in both academic research and petroleum exploration.