Deep basin gas: New insights from kinetic modelling and isotopic fractionation in deep-formed gas precursors

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

“…These coals are more favorable for late methane generation due to the re-incorporation of bitumen and oils into the kerogen, compared with those having lower initial HI values and hydrogen contents. This result is consistent to the previous studies emphasizing the importance of deep methane (Dieckmann et al, 2006;Erdmann and Horsfield, 2006). The observation that C 1 /RC 1-4 ratios are substantially higher for hydrocarbon gases in natural reservoirs than those generated in oil and kerogen pyrolysis experiments has been documented in previous studies (e.g.…”

“…The differences in methane yields among the three experiments at same temperature are relatively minor at EASY%R o < 2.2, but greater with temperature at EASY%R o > 2.2 (Table 2). This result demonstrates that the solid organic residue always retained more hydrogen and higher hydrocarbon generative potential at the postmature stage in the bitumen rich coal than the extracted coal and coal experiments, consistent with previous studies (Dieckmann et al, 2006;Erdmann and Horsfield, 2006). 4.1.5.…”

“…1c). This result suggests that for the bitumen rich coal experiment from the starting temperature to the temperature for EASY%R o 1.0, bitumen generation was suppressed and/or the initial and newly generated bitumen were partially incorporated into the solid organic residue, as suggested by previous studies (Dieckmann et al, 2006;Erdmann and Horsfield, 2006).…”

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

“…Gas generation from the decomposition of organic matter is a very complex process that probably involves reactions of different orders (Schenk et al, 1997b;Domine et al, 1998;Schenk and Horsfield, 1998;Dieckmann et al, 2006;Erdmann and Horsfield, 2006;Mahlstedt et al, 2008). However, for exploration purposes, laboratory and empirical data still support that it could be adequately described by first order reactions, especially for the decomposition of most kerogens of type I/II and crude oils (Schenk et al, 1997b;Schenk and Horsfield, 1998;Waples, 2000).…”

Rapid offline isotopic characterisation of hydrocarbon gases generated by micro-scale sealed vessel pyrolysis

“…In 40 order to overcome the limitations of natural samples, artificial maturation experiments 41 using analytical pyrolysis techniques have been employed to simulate the formation of 42 gases (Michels et al, 2002;Dieckmann et al, 2006). The study of  13 C of the 43 hydrocarbon (HC) gases, particularly when combined with compositional data, is of 44 great importance to evaluate natural gas resources (Boreham et al, 1998 …”