Hybrid microwave-infrared thermal desorption for remediation of oil-contaminated offshore drill cuttings

Drilling operations generate large volumes of drill cuttings contaminated with hydrocarbons, salts, and trace metals, creating significant environmental and regulatory challenges for offshore disposal. Most regulatory frameworks prohibit the discharge of drill cuttings containing more than 1 wt.% oil‑on‑cuttings, necessitating effective on‑site treatment technologies. This study evaluates the performance of a continuous hybrid microwave–infrared thermal desorption process for the remediation of oil‑contaminated drill cuttings. Offshore water‑based drill cuttings contaminated with sour crude oil were collected from Middle Eastern drilling operations and treated using a pilot‑scale unit under inert, low‑oxygen conditions. The process achieved oil-removal efficiencies of 95.0–97.8%, consistently reducing oil on cuttings to below 1 wt.%. Total Petroleum Hydrocarbons (TPH) and Total Oil and Grease (TOG) were reduced by more than 96% across all samples. Thermogravimetric analysis confirmed that most volatile contaminants were removed at temperatures below 110°C, indicating a lower thermal demand than conventional thermal treatments. The results demonstrate that hybrid microwave/infrared thermal processing is an effective and energy‑efficient approach for the treatment of offshore drill cuttings, enabling regulatory compliance while minimising secondary emissions and operational disruption.