Source rock characteristics and Rock-Eval-based hydrocarbon generation kinetic models of the lacustrine Chang-7 Shale of Triassic Yanchang Formation, Ordos Basin, China

Highly variable depositional environment and multiple provenances caused rapid changes in facies laterally and vertically, resulting in contrasting hydrocarbon generation potential and kinetics within the Chang-7 Shale of the upper Triassic Yanchang Formation of Ordos Basin, China. Assessing the shale oil resource potential requires several geochemical models that provide adequate information for characterizing the variations. As traditional generation kinetics is derived from a single immature sample, the kinetic model will not be representative for such variations. This paper discusses the source rock heterogeneity and develops hydrocarbon generation kinetic models for the Chang-7 Shale using kinetics inversion techniques from routine Rock-Eval data. Data collected from various sources for the Chang-7 Shale were analyzed and subdivided into groups based on their bulk geochemical properties and linked to petrophysical facies to describe the facies variation. Hydrocarbon generation kinetic parameters were then estimated for each of the source rock groups. This study suggests that multiple kinetic models better handle spatial variation in evaluating source rock kinetics and resource potential in a lacustrine basin with highly variable lateral organofacies.