Multi-Step Kinetic and Mechanistic Study of Oil-Based Drill Cuttings Pyrolysis Based on the Frazer–Suzuki Deconvolution Method

To achieve the safe reuse of oil-based drill cuttings, this study employs thermogravimetric analysis and pyrolysis-gas chromatography/mass spectrometry to investigate the formation patterns and kinetic characteristics of pyrolysis products in oil-based drill cuttings. The study included a broad temperature range of 100–980 °C and heating rates of 10, 15, and 20 K/min. Employing the Frazer–Suzuki approach from a multi-step-over-single-step perspective, six pseudo-processes (P1–P6) are isolated for the overall pyrolysis reaction of oil-based drill cuttings. Differences in contributions and activation energies were quantified for each stage. The activation energies for the six pseudo-processes are determined to be 60.81, −59.77, 421.10, 231.64, 225.96, and 349.04 kJ/mol, respectively. With increasing temperature, long-chain aliphatic hydrocarbons in products from oil-based drill cuttings pyrolysis tend to convert into short-chain hydrocarbons and form unsaturated hydrocarbons through dehydrogenation. The oil-based drill cuttings pyrolysis process does not follow a single mechanism but is primarily nucleation-controlled, incorporating multiple reaction mechanisms including geometric contraction, diffusion, and power-law effects.