Characterization of oil generation and expulsion from coals and source rocks using diamond anvil cell pyrolysis

A visual technique has been developed using a diamond anvil cell to characterize oil-prone vs. gas-prone coals & source rocks, & evaluate their oil expulsion efficiency. The experiments, conducted using 15 humic or shaly coals, two boghead coals, & eight source rock samples from Taiwan, Turkey, North America, & Australia, show that the technique has potential to distinguish oil-prone coals from gas-prone coals. The oil potential of humic coals was estimated from the amounts of total liquid generated during pyrolysis, which show correlations with the Hydrogen Index (HI) from Rock-Eval pyrolysis & the gas-to-oil ratio (GOR) determined by Py–GC analysis. The changes of visual area (or volume) of neoformed liquid as a function of temperature at four heating rates were used to calculate the extents of kerogen-to-oil transformation for determining the kinetic parameters. The results confirm the kinetic controls on the measured transformations but reveal unusually high apparent activation energies & frequency factors. The use of this technique as a quantitative tool to predict oil generation kinetics should be treated with caution until this discrepancy has been resolved. In addition, this study has demonstrated that the expulsion of oil-like liquid from coals is generally more efficient than from shales, possibly due to the much higher organic content in coal