Oil-Well Drilling

In oil well drilling, a drilling mud is utilized for the purpose of lubrication and also serves as a coolant. Another function of a drilling mud is to keep the hose free from bore cuttings. Most drilling muds are made of a suspension of barites and bentonite or attapulgite clay in either water or a petroleum oil.

To be effective, a drilling mud must have a specific gravity of at least 2.0 and should be thixotropic with appreciable gel strength. Sodium bicarbonate, as a component of drilling mud, reacts with hydroxide ions released while drilling out the case cement.

The sodium salts remaining from the reaction help maintain the mud's viscosity and gel strength. Sodium bicarbonate helps to maintain the pH of the mud and to scavenge caustic calcium oxide turning it into a harmless carbonate. The pH of the carbonate formed is more favorable to maintaining the viscosity of the drilling mud.