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).

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.

An environmentally safe water-base drilling fluid ULTRADRILL;

Research on density of water-base drilling fluid at HTHP;

Although gas drilling increases ROP sharply in the process of drilling in Sichuan and Chongqing area and has been widely applied in the field of drilling,there appears widely serious destabilizing effect of borehole wall when bullheading conventional water-base drilling fluid after gas drilling,which results in frequent backreaming happened in long time and length.