Comments on empirical conversion of solid bitumen reflectance for thermal maturity evaluation

Maturity and thermal evolution differences between two sets of Lower Palaeozoic shales and its significance for shale gas formation in south‐western Sichuan Basin, China

“…The one-dimensional (1D) burial history and thermal modelling constructed for investigated well WY35-1 and well JY2 are shown in Fig- (Schmidt et al, 2019). EqVRo-3: EqVRo = 0.81VLRo + 0.18 (Xiao et al, 2000).…”

“…The maturity of the Lower Palaeozoic shales is typically assessed by EqVRo that is calculated from solid bitumen reflectance or zooclast reflectance. Equivalent empirical equations have been proposed in a diversity of studies (Bertrand, 1990(Bertrand, , 1993Bertrand & Malo, 2001; Bertrand & Malo, 2012;Cole, 1994;Colţoi et al, 2016;Jacob, 1989;Landis & Castaño, 1995;Petersen et al, 2013;Schoenherr et al, 2007) and empirical correlations have been thoroughly reviewed by Hackley and Cardott (2016), Mastalerz et al (2018), Hackley and Lewan (2018), Wang et al (2019Wang et al ( , 2020 and Schmidt et al (2019).…”

“…Recently, a robust correlation between BRo and VRo was established by Schmidt et al (2019) through a comparison between BRo and cooccurring VRo from a great number of previously published data. The…”

“…Nevertheless, Hackley and Lewan (2018) and Schmidt et al (2019) discussed and stated that vitrinite-like materials could be a type of solid bitumen that lacks void-filling texture rather than a product of oil formation. The reflectance values of vitrinite-like particles are similar Caledonian 1000 Xu et al (2012) and Yuan et al (2013) to that of pyrobitumens (Table 3), and the vitrinite-like particles could therefore be probably protobitumen (Bertrand, 1993).…”

“…EqVRo-1, equal vitrinite reflectance calculated by formula; EqVRo, 0.97GRo-0.2(Wang et al, 2019). EqVRo-2, equal vitrinite reflectance calculated by formula, EqVRo = 0.938BRo + 0.3145(Schmidt et al, 2019). Abbreviation: TOC, total organic carbon.a Data from Wang et al (2019).…”