Discussion on drilling fluids optimum usage in complex formation.

In the new west area, formation lithology is complex. The problems related to the drilling fluids were analyzed and discussion was focused on drilling fluids optimum usage in complex formation. Several viewpoints were put forward: 1) To increase drilling fluid inhibitive ability, drilling fluid with high electric property should be used, and additives with opposite electricity should not be employed together. 2) To shorten the drilling fluid preparing time and improve the rheologieal behavior and the colloid stability of a drilling fluid, convenient mud compound powder should be prepared by sodium treatment, wetextrusion,modification and stimulation and: 3) To get high quality mudcake on the wall, the mud should has as high electric property as possible, the solid particle should have certain suitability and reasonable distribution,and certain over-balanced pressure should be kept downhole during the whole drilling process. In addition,inspection and research should be made on phy-chemical properties of mud cake produced by the drilling fluid used.