"In order to deal effectively with reactive clays, a
drilling contractor must be able to identify reactive soil conditions,
understand how and why clay reacts the way it does, and know how to modify the
behavior of reactive soils."
The distinguishing feature of the dual-rotary (DR) drill rig is a lower rotary drive, which is used to independently advance casing up to 40 inches, depending on the drill model.
Drilling muds have four basic properties that determine the behavior of the mud as a drilling fluid – viscosity, density, gel strength and filtration. Several other properties, although of lesser importance, need to be checked, especially if problems are anticipated or encountered.