Decontamination of Drilled Cuttings by a Semi-Industrial Continuous Microwave Dryer

Abstract

RESUMO -The drilling fluids most commonly used in oil and gas drilling operations are synthetic fluids with low biodegradability. These fluids contaminate the drill cuttings, which must undergo decontamination before disposal. Microwave drying has been investigated as a remediation technique for drill cuttings. The objective of this work is update the industry with experimental results of a novel cuttings drying technology based on microwave heating. The expectation is to provide a competitive technology for offshore applications. The motivation is to provide alternatives for efficient cuttings drying to reduce the environmental impact of offshore drilling operations. A semi industrial continuous microwave dryer was initially built to process oily cuttings at flow rates around 0.5 ton/hr. Construction parameters were based on extensive lab scale experiments previously and preliminary tests. Real cuttings and internal olefin based drilling fluids were used. A low field RMN technology was used to evaluate oil contents in inflow and outflow samples. Initial content of synthetic base on the drill cuttings, feed flow rate, residual content and specific energy were some of the variables investigated. Results obtained from preliminary tests and a 9 experiment test matrix show that the technology is able to reduce oil concentration in cuttings to values as low as 0.1% depending on operational parameters. The operational limits of the equipment were successfully pushed to allow processing a cuttings flow rate of 0.75 ton/h. The specific energy of this equipment proved to be competitive with other commercial equipment. The present experimental campaign encourages the continuation of the project signalizing for studies to allow the construction of a field scale microwave cuttings dryer to operate either at a floating rig or at a dedicated ship that would be able to process cuttings generated by several neighbor drilling vessels.