A.Physical and chemical index: Item requirement Appearance dark brown powder Material insoluble to water lower than 2.5 % Moisture lower than 8.5 % Caso4calcium sulfate lower than 3.0 % Total fe 2.5~3.8 % Total cr 3.0~3.8 % Thin (0.66mm surplus of sieve) lower than 3.0 % B.Mud property index: Item fresh water drilling mud Normal temperature, Apparent viscosity mpa.S 20 Rate of reducing viscosity % 85 High temperature Apparent viscosity mpa.S 30 Rate of reducing viscosity % 65 Item salt water drilling mud Normal temperature, Apparent viscosity mpa.S 25 Rate of reducing viscosity % 70 High temperature Apparent viscosity mpa.S 45 Rate of reducing viscosity % 55 C. The methods of use 1.The excellent thinning property of fcls, which shows powerful anti-electrolytes capacity. And it is suitable to all kinds of dispersed mud. 2. Be effective at temperature more than 150~160.It can get better effect when cooperated with lignite derivatives. 3. Fcls may be added into drilling fluid in the form of aqueous solution or powder. To keep ph index at 9.5~10.5, the recommended dosage of thinner is 0.5~1.0 %. D. Package: the net weight is 25kg/bag. Sealed in paper-plastic complex valve bag