Microwave treatment of drilled cuttings contaminated by synthetic drilling fluid

•The drilled cuttings treatment using a microwave batch dryer was accomplished.•Drilled cuttings contaminated with synthetic drilling fluid were treated.•The effect of different variables on the process has been analyzed.•The drying is influenced by fluid concentration, cuttings mass and specific energy.•Residual n-paraffin content less than 1% was achieved.

Drilled cuttings contaminated by non-aqueous fluids (NAFs) are the waste generated by oil well drilling activities. Over the last twenty years, studies have been conducted to assess the effects that these residues have on the environment in both offshore and onshore scenarios. More restrictive environmental legislation and the need to reduce drilling costs (exploration and production) have led to the optimization of solid–liquid separation. Currently, in Brazil, the environmental offshore discharge threshold for cuttings contaminated by synthetic fluids is 6.9%w/w by mass. Microwave radiation is a promising technology to remove the organic phase of these drilled cuttings. This paper presents microwave heating technique as a method for the treatment of drilled cuttings contaminated by NAFs. This drying methodology was applied to contaminated cuttings and studied through a Central Composite Design of Experiments, where the variables were drilling fluid concentration, mass of cuttings and specific energy. The responses were residual n-paraffin and residual water contents.