Drill cuttings are particles of crushed rock produced by the grinding action of the drill bit as it penetrates into the earth. Drill cuttings range in size from clay-sized particles (~ 2 μm) to coarse gravel (> 30 mm) and have an angular configuration. Their chemistry and mineralogy reflect that of the sedimentary strata being penetrated by the drill.
An important problem in the oil industry is the treatment of produced water, especially in the case of offshore oil production where space and floor area, needed for the separation equipment, are extremely costly. Increased production of water occurs when an oil field matures, and the availability of efficient and cost-effective techniques partly determines the period during which economic production is possible. For the final de-oiling process several techniques are available, of which plate separation, centrifugation and the use of hydrocyclones are important ones. Common characteristics of these three techniques are that only insoluble oil components can be removed, and that the prevailing separation process is movement of the oil droplets with respect to the continuous phase, water, as a result of an external force, viz. the gravity force or the centrifugal force.
Liquid/gas systems use 75% to 100% of the volume of drilling fluid required (for a 120-ft/min annular velocity) with typical fluid systems. These systems may be water/air, water/nitrogen, oil/gas, or oil/nitrogen.