Transport properties of discharged synthetic based drilling wastes

A study was conducted in which a digital imaging system was used to study the effects of offshore discharges of drilling cuttings and synthetic based drilling fluids associated with petroleum exploration and production activities. The objective was to determine the transport and fate of the discharges in the marine environment and how they are affected by the settling velocity and flocculation process. The study examined the impact that particle shape and size have on the settling mechanism. It also examined the effects of salinity, fluid shear, discharge concentration, and oil components on the rate of flocculation and the settling speed of flocs. Samples collected from an oil exploration well in east coast Canada were placed in a plexiglass settling column with both freshwater and seawater to measure the settling velocities. Applied shears ranged from 25 to 200 per second and the concentrations ranged from 25 to 200 mg per litre. A thermally treated sample was also used to examine the impact of oil components on flocculation. It was determined that untreated cuttings have a tendency to clump together and settle quickly. Treated cuttings settle slowly as individual particles. The settling velocity appeared to be a function of particle sphericity and diameter. The steady state median floc size decreased with an increase in shear stress and concentration. Particles in seawater flocculated faster than those in freshwater. Flocs from untreated cuttings settled faster than flocs from thermally treated cuttings