Optimization of the batch decontamination process of drill cuttings by microwave heating

Abstract

In the drilling of oil and gas wells synthetic fluids can be used to remove rock fragments generated during the operation. However, the use of these fluids generates a solid-liquid mixture that must be separated in order to reduce the operational costs by the recovery of the fluid adhered to the solids and also to guarantee compliance with environmental legislation regarding drilling waste disposal. Therefore, the objective of this study was to evaluate the influence of some process variables on the decontamination of drill cuttings by microwave heating. Experimental conditions relative to the heating time, bed temperature and mass of samples contaminated with synthetic drilling fluid were optimized by means of a design of experiments (DOE) and a canonical analysis, reaching organic residual contents lower than 1% (mass). Furthermore, numerical simulations were executed for a better understanding of the microwave heating and drying process. Analyses using the gas chromatography technique were performed in order to evaluate possible composition changes in the recovered liquid samples during the condensation operation, which showed themselves to be sensitive to heating at higher temperatures.