An experimental comparison of gas generation from three oil fractions: Implications for the chemical and stable carbon isotopic signatures of oil cracking gas

Hydrocarbon generation from coal, extracted coal and bitumen rich coal in confined pyrolysis experiments

“…Previous studies demonstrated that methane d 13 C values at first decrease to a minimum value, and then increase with temperature or R o % in confined pyrolysis experiments on kerogen and coal samples (Lorant et al, 1998;Tang et al, 2000;Liu et al, 2004;Xiong et al, 2004;Xiao et al, 2005Xiao et al, , 2006Xiao et al, , 2009Tian et al, 2012), as observed in the present study (Table 4). Using the method of Tang et al (2000), this trend for methane d 13 C values can be modeled mathematically (e.g., Xiao et al, 2005Xiao et al, , 2006Xiao et al, , 2009Tian et al, 2012).…”

“…À22.86‰ (Table 1). This phenomenon was also observed in previous confined pyrolysis studies on type II kerogen (Lorant et al, 1998), purified vitrinite from three different coals and asphaltenes separated from crude oil (Tian et al, 2012). This result may indicate that most methane shared a common precursor with wet gases in confined pyrolysis experiments.…”

“…Using the method of Tang et al (2000), this trend for methane d 13 C values can be modeled mathematically (e.g., Xiao et al, 2005Xiao et al, , 2006Xiao et al, , 2009Tian et al, 2012). The reversal in methane d 13 C values with temperature and R o % can be interpreted to be the result of two precursors for methane.…”

The effect of oil expulsion or retention on further thermal degradation of kerogen at the high maturity stage: A pyrolysis study of type II kerogen from Pingliang shale, China

“…6i-l), which has been well reported by previous studies (Pan et al, 2010(Pan et al, , 2012Tian et al, 2012). The generation curve of total gas mainly reflected the primary cracking of oil (C 6+ ) into gas, while the generation curve of total gas in volume could be used to demonstrate the secondary cracking of wet gas components (C 2-5 ) into methane (Pan et al, 2010).…”

Effects of U-ore on the chemical and isotopic composition of products of hydrous pyrolysis of organic matter

“…In the pyrolysis experiments, d 13 C 1 initially decreased from a high value to a minimum value, and then increased with temperature and EasyR o . This reversal implies that carbon cracking changed from labile bonds (between carbon and heteroatoms) to C-C bonds (Cramer 2004), and this observation is consistent with many previous studies Lorant et al 1998;Tang et al 2000;Tian et al 2012;Xiao et al 2005;Xiong et al 2004). All pyrolysis experiments were conducted under the same pressure, excluding the possibility of varying isotopic fractionation during gas generation and expulsion under different pressures.…”