Chemical Washes

Displace mud via thinning and dilution

Chemical washes are fluids having a density and viscosity close to that of water or oil. As chemical washes are very low viscosity, they are pumped in turbulent flow. When pumped ahead of the cement slurry, they assist in mud removal by diluting, thinning and dispersing mud. This aids in removal of the mud, improving the quality of the bond between the cement and the casing and the formation.

Schlumberger offers a comprehensive line of chemical washes for any application, whether the mud is water- or oil-based.

Water-base mud compatibility

CW7 wash is pumped ahead of cement to separate it from water-base drilling fluid. It disperses the mud and removes mud from the formation face by turbulent flow. CW100 contains a fluid loss additive to prevent losses into permeable formations in addition to providing the same mud dispersion and removal properties.

Oil-base mud compatibility

When oil-base fluid is used for drilling, base oil is the first preflush fluid and is followed by chemical washes containing surfactants and solvents. Washes containing surfactants and solvents disperse the oil phase in water and convert surfaces to water wet.


CW8 provides the same separation and mud removal functions as CW7 when conventional oil-base muds are in the well.


CW8-ES performs the same functions with an environmentally friendly fluid.