How they are used

Using drilling liquids and muds accomplishes four things:

reduce the amount of friction on the drilling rig

stabilize the walls of the hole to prevent a cave in

carry out debris, called CUTTINGS, from the hole

suspending the cuttings when there is a pause in drilling, as when the rig is brought in and out of the hole


Both liquid and mud are used to drill boreholes but the COMPOSITION is DIFFERENT. One term is often used for the other, but strictly speaking gaseous drilling fluid, using an array of gases, is a fluid. But fluids that are water or oil based are called mud.

seven basic types of drilling fluid though technically some are actually fluid and some are mud. What geotechnical engineers use depends on the type of drill they are using, the geology of the area and what they are drilling for.

compressed air

a mix of compressed air and water. Its advantage is the GREATER cooling it provides and better control of dust.

a mix of compressed air, water and polymer, often used as foaming agents

water by itself, often used in offshore drilling

water-based mud, which is water plus clay and chemicals

oil-based mud, which is mud with a petroleum product like diesel. It has greater lubricating and cleaning ability.

synthetic-based fluid, also called low toxicity oil based mud. Its big advantage is fewer TOXIC fumes, essential in enclosed spaces on offshore rigs.