Pyrolysis kerogen decomposition

Kerogen Decomposition. The thermal decomposition of oil shale, ie, pyrolysis or retorting, yields Hquid, gaseous, and soHd products. The amounts of oil, gas, and coke which ultimately are formed depend on the heating rate of the oil shale and the temperature—time history of the Hberated oil. There is Htde effect of shale richness on these relative product yields under fixed pyrolysis conditions, as is shown in Table 5 (10). 

The rate of kerogen decomposition into oil and gaseous products can be an important factor in process design, as can the relative amount of oil and gas produced. Nonisothermal gravimetric analysis was used to compare the relative thermal decomposition rates of the kerogens in the shales under investigation. Details of the pyrolysis studies are presented in the following sections. 

Ra = R3 -h (10Rc)/0.9. The RC (residual carbon) term represents heavy bitumens or recycled kerogens not directly volatilized by pyrolysis, but that could be oxidized to CO2 or CO in the separate oxidation step (Lafargue et al. 1997). Flowever, the Kuparuk formation often contains cements, siderite among others, which decompose to CO2 or CO at temperatures reached in the oxidation step of Rock-Eval 6 analysis. Unacceptable variability in RC was observed in pyrolysis of Kuparuk samples, possibly because of decomposition of carbonate minerals. Therefore, a Y coefficient was adopted to correlate Rock-Eval 6 pyrolysis results to petroleum density, where F=(R1+R2)/ (R1 +R2 + R3). 

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