Aplicação de secagem por microondas no tratamento de cascalho de perfuração

Abstract

Coated or contaminated cuttings with drilling fluid are a residue of drilling. A more restrictive environmental legislation and the need to reduce the costs of drilling lead to optimization of solid-liquid separation and recycling drilling fluids. Shale shakers, hydrocyclones and centrifuges are examples of equipments used for processing drilling fluids. Nowadays, vertical filter centrifuges are used to adjust the cuttings into environmental laws. In this context, this work brings a study on the. Exploratory tests were carried out on domestic microwave oven and indicated the use of this technology as a promising alternative for cuttings decontamination. In this stage, residual n-paraffin contents lower than 2% were achieved. From these evidences, a microwave oven in bench scale was developed for drying contaminated cuttings. A set of aspects of the process were evaluated in this experimental unit. This drying methodology applied to contaminated cuttings was studied through several experimental tests and through a Central Composite Design of Experiments where the manipulated variables were drilling fluid concentration, mass and specific energy. The response variables were residual water and n-paraffin content, percentage of n-paraffin removed, mass flow and mass of n-paraffin removed per unit of energy. Initial tests showed that temperature does not affect the removal efficiency of the organic phase, but seems to affect the quality of the recovered material in the process. The power has negative influence on the cuttings decontamination and specific energy positively affects this process. From the Central Composite Design proposed, it is evident that microwave cuttings drying is favored by the increased mass and specific energy and harmed by the increase of the initial fluid concentration. The results show that cuttings drying carried out on microwave dryer reach levels of residual n-paraffin content lower than ones currently achieved by vertical filter centrifuge (about 4 %), reaching percentages below 1 %. Furthermore, the recovered fluid is free of solids and may be directly reused. Finally, this work has produced a set of important information to the oil industry and even has direct application in it.