Abstract: Aqueous chemical washes suitable for use in conjunction with well cementing operations are disclosed which comprise water, an anionic or a non-ionic surfactant (or a combination thereof) and a fluid loss control agent of the type described in U.S. Pat. No. 3,891,566.

Abstract: A composition designed for dissolution or dispersion in water to give an aqueous treatment fluid having a yield point of zero, at a temperature between about 85.degree. and about 160.degree. F., which is compatible with cement slurries and with drilling muds and a method of using same to displace a drilling mud from a borehole which penetrates a subterranean formation, particularly immediately preceding the injection of a fluid such as a cement slurry, and which also exhibits good fluid loss control and may be adapted for use with either water-based or oil-based drilling muds.