Estudo da extração sólido-líquido para tratamento de cascalho de perfuração usando microemulsão

Abstract

The drill cuttings are a waste originated from oil exploration activities, which is highly toxic, due to the presence of n-paraffin from the drilling fluid adsorbed to it (waste class I - NBR 10004: 2004). This study presents an alternative to the treatment of drill cuttings, using microemulsion systems, aiming at the removal of n-paraffin and thereby reducing the environmental impact. The variables of solid-liquid extraction (solvent, solvent/drill cuttings, stirring speed and contact time) were studied in order to optimize them to provide better extraction performance. For the quantification of the extracts, gas chromatography analysis with a flame ionization detector (GC-FID) was used. Six microemulsion systems were used and the results showed that microemulsion using surfactant Alkonat® L90 (WS = 83%, C/S = 16%, and OP = 1%) presented the best extraction percentage among the studied systems. In the study of the microemulsion/gravel ratio, the 0.25 ratios were tested; 0.5, 1.0, 1.5 and 2.0, and the equal ratio 1.0 was the best result. In the study with variable stirring speed (0, 48, 84 and 132 strokes) was identified that with increasing stirring speed also is the increase in the percentage of extraction. In the contact time parameter, the times of 1, 10, 20, 40, 80 and 160 minutes were studied and an increase in the percentage of extraction was observed with increasing time, reaching higher levels of 76% extraction with time of 80 minutes. The system has been tested for reuse and has shown reusability in up to two extractions without significantly losing efficiency. Results show the extraction percentage up to 86%. In the study of solid-liquid extraction, it was concluded that the lower the contamination, the higher the extraction percentage, reaching a result of 96.47% extraction with drill cuttings contaminated with 6.4% n-paraffin. It is concluded that the use of microemulsion systems in the n-paraffin extraction of drill cuttings promoted the treatment at high levels, constituting a viable alternative for waste treatment and placing it at acceptable levels of contaminants (6.9% fluid retained in drill cuttings - US EPA, 2000).