THE MAJOR WATER BASED DRILLING FLUID ADDITIVES
Water Based Drilling Fluids Additives

 a) Viscosity control drilling fluid additives
Commercial clays are used to control the viscosity of water based muds. These are graded according to their yield. The yield of a clay is defined as the number of barrels of 15 centipoise viscosity mud which can be obtained from 1 ton of dry clay. (A 15 centipoise viscosity will support barite). Wyoming bentonite has a yield of about 100 bbl/ton, whereas native clays may only yield 10 bbl/ton.
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