Contents lists available at ScienceDirect International Journal of Coal Geology journal homepage: www.elsevier.com/locate/coal Generation kinetics based method for correcting effects of migrated oil on Rock-Eval data – An example from the Eocene Qianjiang Formation, Jianghan Basin, China Zhuoheng Chen a , Maowen Li b, ⁎ , Xiaoxiao Ma c , Tingting Cao b , Xiaojun Liu a , Zhiming Li b , Qigui Jiang b , Shiqiang Wu d a Geological Survey of Canada, 3303-33 Street NW, Calgary,Alberta T2L 2A7,Canada b China State Key Laboratory of Shale Oil and Shale Gas Resources and Effective Development, Sinopec Petroleum Exploration and Production Research Institute,31 Xueyuan Road, Haidian District, Beijing 100083,China c China University of Petroleum (Beijing), 18 Fuxue Road,Changping District, Beijng 102249,China d Sinopec Jianghan Oilfield Company,18 Daxueyuan Road, Gaoxin District, Wuhan, Hubei 430223, China ARTICLE INFO Keywords: Shale gas/oil evaluation S1 carry-over Activation energy Recalculation of Rock-Eval parameters ABSTRACT 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. 1. Introduction Source rocks in the Eocene Qianjiang Formation in the Jianghan Basin of China appear to contain indigenous organic matter as well as migrated hydrocarbons (including non-hydrocarbon soluble organic matter) likely expelled from downdip source rocks with higher thermal maturity within the same stratigraphic unit (Li et al., 2018a). Presence of large amounts of migrated hydrocarbons in the samples leads to an anomalously high S1 peak and an elevated low-temperature false S2 peak (S1 carry-over) during Rock-Eval pyrolysis, thus affecting deri- vative Rock-Eval parameters, such as S1, S2, TOC, T max and HI, which are fundamental in source rock evaluation and resource potential esti- mation (Espitalie et al., 1977; Jarvie and Baker, 1984; Jarvie and Lundell, 2001). Efforts have been made in new laboratory procedures to reduce the effect of migrated hydrocarbons in source rock analysis using Rock-Eval 6 equipment. For example, Romero-Sarmiento et al. (2016) and King (2015) discussed new instrument protocols for reducing “S1 carry-over” in samples of liquid-rich shale reservoirs when using Rock-Eval 6 and HAWK pyrolysis equipments. This effect is complicated by the so called oil adsorption in early mature source rocks. Delveaux et al. (1990) recognized the impact of heavy oil and bitumen on Rock-Eval pyrolysis. This arises because early products of kerogen thermal degradation contain large amount of high- molecular-weight constituents of bitumen and crude oil. Similarity in chemical structures and physical/chemical properties between early products and their precursor kerogen, in combination with large spe- cific surface area of small nano- pores in organic matter, results in strong adsorption capacity from the hosting rock. Delveaux et al. (1990) proposed a two sample procedure, a whole rock-sample and a post- solvent extracted replicate to handle the problem of lack of re- presentative response for these hydrocarbon components. Many authors (Jarvie, 2012; Burnham, 2017; Burnham et al., 2018; Jiang et al., 2016; Li et al., 2017; Abrams et al., 2017) discussed this issue in the light of oil adsorption and their impact on the total oil yield estimation. Li et al. (2018b) presented a numerical solution for separating the S1 carry-over https://doi.org/10.1016/j.coal.2018.05.010 Received 28 March 2018; Received in revised form 21 May 2018; Accepted 24 May 2018 ⁎ Corresponding author. E-mail address: limw.syky@sinopec.com (M. Li). International Journal of Coal Geology 195 (2018) 84–101 Available online 31 May 2018 0166-5162/ © 2018 Elsevier B.V. All rights reserved. T