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

Abstract

The drilling fluids most commonly used in oil and gas drilling operations are the non-aqueous drilling fluids. These fluids adhere to the drilled cuttings, and because of the Brazilian environmental legislation demands, they need to undergo a reduction on the organic phase content before disposal. Microwave drying has been investigated as a remediation technique for drilled cuttings. The objective of this work is update the industry on the experimental results of a new cuttings drying equipment based on microwave heating. The motivation is to provide new field alternatives for efficient cuttings drying. A semi industrial continuous microwave dryer was built to process cuttings wet with an organic phase at a flow rate of 0.5 ton/hr. Construction parameters were based on extensive lab scale down experiments. Real cuttings and internal olefin based drilling fluids were used. A low field Nuclear Magnetic Ressonance (NMR) technology was used to evaluate oil contents in inflow and outflow samples. During the tests the initial content of synthetic base on the drill cuttings and feed flow rate were the controlled variables and the response variables were the residual content and specific energy (the amount of energy spent per unit of mass). Results obtained from preliminary tests and a test matrix show that the technology is able to reduce base oil concentration in cutting to values as low as 0.1%. The operational limits of the equipment were successfully investigated to allow processing a cuttings flow rate of 0.75 ton/h. The specific energy of this equipment proved to be competitive to become a commercial equipment. The present experimental campaign encourages the continuation of the research with the intent to build full-scale field microwave cutting dryer to operate either at a floating rig.