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The use of drilling fluids in oil drilling process generates solid–liquid mixtures that must be separated. One of the aims of this process is compliance with environmental laws regarding to disposal of waste from drilling activities. The present study aims to investigate the microwave drying of contaminated drilled cuttings. The aspects investigated are: cuttings size and shape, bed height, composition of the drilling fluid, and application of a sweep gas. The results show that mixtures of cuttings containing rounder and larger particles lead to greater removal of drilling fluid than mixtures that consist of less‐round and finer particles. The increase of the bed height leads to higher efficiency in terms of n‐paraffin removal. The use of a sweep gas increases the n‐paraffin removal from 75 to 90 %. The higher the water content on the drilling fluid, the greater the removal of organic phase. The microwave heating does not cause significant changes in the organic phase recovered.

Drilled cuttings contaminated by non aqueous drilling fluids are the major waste from oil well drilling activities. More restrictive environmental legislation has led to the search for alternative technologies to promote cuttings decontamination according to the law. The mixture of cuttings and fluid returning from the well goes through a set of separation equipments, called solids control systems, in order to recover the drilling fluid for reuse. The cuttings from the solids control system must be decontaminated before they can be discharged into the sea. Microwave heating has been studied over the past few years as an alternative to promote the decontamination of this waste and has been shown to be a promising technology. This work aimed to investigate fundamental aspects of microwave heating and drying of drilled cuttings. The heating curve of two different drilling fluids commonly employed in well-drilling operations was obtained. The kinetics of drying of cuttings contaminated with these drilling fluids was also investigated. It was evaluated the behavior of organic phase and water removal in the microwave drying process.

Drill cuttings generated by oil and gas drilling process are incorporated into the drilling fluid to ensure an efficient drilling and solids removal. The drilling rigs have a separation system accountable for separating drill cuttings and drilling fluids. Microwave drying is a new technology of separation that has been studied as an alternative to the currently drill cuttings dryer used. The results obtained in preliminary studies showed that this microwave drying is sensitive to different oxides presents into the rock. Thus, this study aimed to describe the microwave heating kinetics of some rocks in order to verify the interaction of oxides with electromagnetic waves. For this, the oxide contents of the rocks were determined by X-ray Fluorescence and different rocks were heated in a microwave heating unit. The results showed that the relationship between the temperature and heating time is exponential and depends on the rock oxide contents. It was found that the iron oxides may be unstable at microwave and rocks with high levels of magnesium oxides and sulfates tend to be good absorbers of microwave. Rocks containing high levels of calcium, silicon, titanium, barium and chloride (NaCl) are not good absorbers of microwave. It was also noted that faster solid heating, lesser the efficiency of microwave drying.