Generation kinetics based method for correcting effects of migrated oil on Rock-Eval data - An example from the Eocene Qianjiang Formation, Jianghan Basin, China

Migrated hydrocarbons occur commonly in liquid-rich source rock reservoirs and can distort analytical results of programed pyrolysis. Disregarding the effect may result in unreliable data interpretation and inappropriate hydrocarbon generation kinetics. This paper proposes a method based on kerogen kinetics for characterizing the impacts, estimating the severity and subsequently minimizing the effects by removal of the migrated components from the oil-stained samples through a numerical approach. The restored hydrocarbon pyrograms are then used for recalculation of relevant Rock-Eval parameters and proper construction of generation kinetic models. The proposed methods and workflow were applied to the source rock samples from the Qianjiang Formation, a confined source rock system imbedded in salt layers, where contamination from migrated hydrocarbons is common. An additional Rock-Eval dataset consisting of whole-rock samples and post-solvent extracted replicates was used to validate the methods. The validation results show that the proposed numerical approach is a cost-effective alternative to the traditional laboratory solution.