A KDF water base mud that could be used at high pressure high temperature conditions was designed for use in this well having elevated temperatures and high pressures.

The titled ultra-concentrated AA/AM/AMPS tercopolymer inverse emulsion(IE) with white oil as dispersing medium can be used directly in water base drilling fluids as filtrate loss reducer.

The syntheses and properties of 4 environmentally safe solid additives for water base drilling fluids are introduced briefly and these are: modified natural macromolecular coating (inhibiting) agent IND30 and filtrate loss reducer NAT20; non-fluorescent "white asphalt" NFA25 (modified oily substances soluble partially in water and in oil); and powdered polyol PGCS1 (EO/PO copolymer).

In the application of ultra low-density drilling fluid,compared with conventional oil base drilling fluid,the invert emulsion mud is easy to ignite and has poor safety while hollow micro-sphere glass beads polysulfonate drilling fluid by American 3M Company has not only technical difficulties in controlling the volume of solid phase but also high cost in drilling fluid.

Wettability reversal agent is an important additive for oil base drilling fluid.

The copolymer and 20 percent of t concentrated sulphuric acid react at 50℃ for 2 hrs to produce a sulfonated styrene/itaconic acid copolymer-viscosity reducer for water base drilling fluids SSHIA.