The Application of Cyclone Desorption Technology for OBM Drill Cuttings Disposal

Abstract

With the flourishing shale gas exploitation produces more oil based mud (OBM) drill cuttings, the hard-to-treat hazardous waste burden the local environment heavily. However, the problems of high energy consumption, high treating cost and high secondary contamination risk still remain unsolved for mainstream technologies such as thermal distillation, incineration and chemical extraction. Therefore, a new method and device based on cyclone desorption of high speed self-rotation to dispose of OBM drill cuttings are put forward to overcome the challenge. The working process includes: viscosity reduction in heated gas; cyclone deoiling; condensation and recycling of exhaust; separation of oil and water in coalescer. It is found that the self-rotation speed of solid particles in a 3-dimensional rotating turbulent flow field of cyclone is as high as 2,000 to 6,000 rad/s which coexists with revolution speed of 20 to 300 rpm. The remarkable pulsing centrifuge forces in the self-rotation and revolution coupling motion can enhance the desorption process of the oil so as to accomplish the separation and enrichment of oil and solid phase, and deep removal of organics from OBM drill cuttings. It turned out that the deoiling efficiency of OBM drill cuttings, a sample from Chongqing shale gas field, increased as the processing time longer and, to be exact, after 2.1 seconds the oil content fell from 17.9% to 0.16% which is about a half of the maximum allowable content of petroleum in pollutants, 0.3%, in GB 4284-84 "Control Standards for Pollutants in Agricultural Sludge". In general, the innovation of cyclone desorption of high speed self-rotation is the pulsing centrifuge force of self-rotation and revolution coupling motion, so it's free of chemical addition and high heating temperature. Therefore, the application of cyclone desorption of high speed self-rotation for OBM drill cuttings disposal is expected to lower treatment cost, enhance processing effect, and finally improve the environment of shale gas exploitation area and contribute to energy development.