1. n. [Drilling Fluids]
Drilling operations using a water-base drilling fluid that contains few solids. Clear-water drilling is done in "hard rocks" in which density and fluid loss are not critical. Rapid drilling rate is the incentive for using a solids-free mud. Fluid returned to the surface must be screened and processed by hydrocyclones and centrifuges to remove larger solids. Colloidal solids can be agglomerated by adding polymers and removing the aggregates. Polymers such as acrylates, acrylamides and partially-hydrolyzed polyacrylamides are used. They are added at the flowline as mud exits the well or added in pits downstream from the flowline.