Propriedades dielétricas e cinética de secagem de cascalhos de perfuração de poços de petróleo e gás utilizando micro-ondas

Abstract

Drilling is one of the phases of oil and gas production. During this phase, cuttings are created and transported from the well to the surface due to the circulation of fluids. When synthetic drilling fluids are used, the drill cuttings must be treated before being disposed in order to prevent potential environmental impacts. The microwave drying technique is a promising alternative to the treatment of these drill cuttings contaminated with synthetic-based fluids. In microwave ovens, the heat is created by the direct transformation of the electromagnetic radiation into thermal energy within the material to be dried, which results in a higher energy efficiency and lower drying time when compared to other thermal desorption techniques. Thus, this study aimed to investigate the drying of drill cuttings contaminated with an olefin-based fluid in a batch scale microwave furnace, the Milestone NEOS GR. For this, drying tests were performed, varying the initial organic content, the power applied and the drying time. In order to better understand the behavior of the sample in relation to the microwaves, dielectric properties were measured. Based on the results obtained, a kinetic model was proposed, named Kinetic Model of Microwave Drying (KMMD). This model was in agreement with the experimental observations and the coefficients of determination (R2) of the obtained curves varied from 0.9836 to 0.9977, what suggested that the model described the drying kinetics of the evaluated material well. In addition, a Central Composite Design (CCD) was proposed considering three variables: initial olefin content, power and time; the residual content of olefin was the response variable. All variables were significant. The initial content negatively influenced the response. For power and time, the effect was positive. The results showed that cuttings can be decontaminated at levels lower than those required by environmental legislation, reaching residual mass contents lower than 1% in some tests. Finally, the liquids recovered in the kinetic tests were analyzed using the gas chromatography technique. Fluid degradation was observed in tests with long drying time and high applied power.