Kinetic Analysis using the HAWK
Wildcat Technologies has developed the HAWK Instrument for Pyrolysis, TOC and Kinetic Analyses. Using the HAWK, Kinetic analysis begins with pyrolysis of source rock samples using at least 3 heating rates.
The data files are then processed in accordance with Arrhenius equation (k = A x exp(Ea/RT),which expresses the quantitative relationship between the rate of a reaction (k) and temperature (T)
This provides both their distribution of activation energies and the associated Arrhenius factor, which are then used to calculate kerogen decomposition rates. In the Arrhenius equation, A is a constant called the Arrhenius factor (or probability factor or frequency factor), Ea is the activation energy, and R is the universal gas constant (8.314 × 10-3KJ mol-1 K-1). An example of Kinetic analyses are those done on the Monterey Formation samples from Lions Head (Fig. 3) which show very narrow range distribution of activation energies similar to classical Type II kerogen whereby the whole decomposition reaction is described by 2 to 4 principal activation energies (Jarvie and Lundell, 2000). One group of Monterey Formation samples is shown to convert to hydrocarbons at a much lower thermal exposure than other kerogens (Fig. 4).
After pyrolysis (S1 (mg hydrocarbons/g rock), S2 (mg hydrocarbons/g rock), S3 (mg CO2/g rock), S4 (mg carbon/g rock), and Tmax (°C)) and TOC (wt. %) measurements are completed, selected rock samples are evaluated by open system pyrolysis using the HAWK to determine kinetic parameters; these include a distribution of activation energies (Ea) and a single Arrhenius factor (A), which are used to calculate kerogen decomposition rates using rate equations and an assumed first-order reaction (Jarvie and Lundell, 2001 ).
The selected samples are first extracted for 24 hours in a soxhlet extractor utilizing a binary azeotropic mixture of chloroform and methanol (89:11, vol: vol) to remove as much of the extractable organic matter (EOM) as possible. Each extracted sample is then dried and reanalyzed for TOC and pyrolysis data to evaluate any changes in remaining potential (S2 value) due to loss of heavy EOM such as resins and asphaltenes.
The extracted rock samples are used for determination of kinetic parameters. Data from the HAWK (Wildcat Technologies) at six heating rates (analyzed in duplicate) from 250 °C to 900 °C are used in the HAWK’s automatic acquisition mode to construct kinetic data files consisting of time, true pyrolysis temperatures and rate of kerogen decomposition. These files are processed using software such as the kinetics2015 software (developed by Lawrence Livermore National Laboratory). Kinetics2015 software is available for purchase from Wildcat Technologies or GeoIsoChem.
Report Available for Purchase
Wildcat Technologies has the Green River Formation Kinetics Report available for purchase. This report comprises of:
- The Green River Formation’s bulk kinetics data file at three heating rates of 1 °C per minute, 5 °C per minute and 30 °C per minute.
- The Green River Formation’s processed kinetics data in graph format showing the quantitative relationship between the rate of a reaction (k) and temperature (T).
- The Green River Formation’s interpreted kinetics report discussing this formation’s range of activation energies, their associated kerogen decomposition rates, thermal exposure, hydrocarbon products and comparison with those of the Kerogens of selected shale formations.
Burnham, A. K., 2011, Principles of Kinetic Analysis for Condensed-Phase Thermal Decomposition.
Jarvie, D.M, and L. L. Lundell, 2000, Kerogen Type and Thermal Transformation of Organic Matter in the Miocene Monterey Formation.