Development and performance of a continuous industrial microwave dryer for remediation of drill cuttings

In the operation of drilling oil and gas wells, fragments of reservoir rocks generated by the action of the roundabout drill, generically denominated by drill cutting, are loaded to the surface by the drilling fluid. Most of the drilling fluids used in Brazil are not aqueous because they have an organic base and have been classified as synthetic base fluids. The drill cuttings contaminated by this organic compound must be separated from the drilling fluid for later disposal in the environment. Drying technology through microwaves has shown promise by reaching contaminant levels of below 1%. However, there is currently no device on an industrial scale which is both efficient and reliable in the treatment of drill cuttings with low energy consumption that is capable of reaching residual contaminant contents (<1%). Therefore, in this study a unit for microwave drying has been developed on an industrial scale in continuous feed, to the remediation of drill cuttings. The equipment has been tested in real conditions of operation, using mass flow rates between 250 and 750 kg/h and organic initial contents of 7.5, 10 and 12.5%. Drill cuttings of offshore type and also pre-salt layers have been evaluated. The results have shown that the proposed device has the capacity to process mass flow rates up to 750 kg/h and is able to reduce the residual contents of hydrocarbons from drilling fluid to 0.1% at a mass flow rate of 250 kg/h, with commercially variable energy consumption. It has also shown a very satisfactory performance in drill cuttings of pre-salt with the efficient removal of organic-based near offshore drill cuttings.