Mud Rotary

Mud rotary is a drilling method that uses liquids as the drilling fluid rather than liquid drilling methods.  The drilling fluid is circulated down through the inside of the drill pipe bringing the cutings back to up the boring.  The head of the drilling fluid maintains a positive pressure against the bore hole preventing caving.  The drilling fluid is discharged into a tub to allow drill cuttings to settle out.  The drilling fluid also acts as a lubricant and cools the drill bit.  A common fluid is water/bentonite slurry mixed in varying consistencies.  The mud rotary method is most useful in hard formations where hard formations are encountered, or the depth of hole exceeds the limits of other methods.  Use of drilling fluids may be limited by restrictions on environment assessment studies.  Continuous sample tube systems and standard penetrating systems are also available for use with this method.