The extrapolation of high-temperature pyrolysis data to kerogen maturation conditions occurs over many orders of magnitude. Quite possibly, the chemical kinetics of a high-temperature regime may be different for a low-temperature regime, making the extrapolation meaningless.

We have mildly thermally treated Green River kerogen to remove the low activation energy non-oil-bearing material. Low-temperature (209°-388°C) isothermal reaction measurements on this refined material indicate that the same reaction kinetics for the oil production from Green River kerogen obtained at high temperature (400°-500°C) are valid as low as 209°C. The same Arrhenius parameters apply over the entire range: k = 1 × 10¹³ exp (-51300/RT) sec^-1. This means that the overall decomposition mechanism, most probably a radical decomposition mechanism applicable at high temperature, is also applicable at low temperature (209°C), and, perhaps, geological (i.e., 50°-160°C) temperatures. Olefins are initially produced in a ydrocarbon radical decomposition process. We show that with time, these olefins are converted to paraffins, presumably using the residual hydrogen in the converted kerogen.