Guidelines for kinetic input to petroleum system models from open-system pyrolysis

Abstract

Abstract Reliable basin and petroleum system models (BPSM) require accurate kinetic parameters for the conversion of source-rock kerogen to petroleum. The purpose of this paper is to dispel widespread uncertainty about kinetic input to BPSM by providing guidelines based on interpretation of previously published data for 81 worldwide source rocks containing various kerogen types. • Kinetic response is unrelated to kerogen type as defined by Rock-Eval pyrolysis hydrogen index. Default kinetics in BPSM software may differ from that for the same kerogen type in different study areas. Use default kinetics with caution when appropriate measured kinetics are unavailable. • Measure kinetic parameters using thermally immature equivalents of the source rock, which may require multiple samples because kerogen kinetics can vary laterally and vertically in each source rock. • Descriptions of depositional environment are insufficient to define kerogen type or kinetic response in different basins. • Optimize multiple-run programmed pyrolysis results for both the activation energy (Ea) and frequency factor (A). Assuming a universal value of A rather than optimizing both Ea and A can yield temperature errors of 20 °C or more when extrapolated to geologic time. • Alternative kinetic models to calculate vitrinite reflectance (Ro) may be more accurate than Easy%Ro for BPSM calibration. In the Aurora-1 and Inigok-1 wells in Alaska, Basin%Ro and Easy%RoDL, more accurately replicates the dogleg in vitrinite reflectance versus depth commonly observed in wells at depths corresponding to ∼0.7–1.0% Ro.