The concentration of rheology modifiers used is typically from 0.1 to 1%, more usually from 0.3 to 1%, weight/volume of the fluid. corrosion inhibitors--are commonly included in drilling,completion and workover fluids, because well fluids including salts e.g. brine solutions as in invert emulsion drilling muds, are corrosive to some extent towards metal components e.g. pipework, that they contact,