Introduction In the

oil industry The petroleum industry, also known as the oil industry or the oil patch, includes the global processes of exploration, extraction, refining, transportation (often by oil tankers and pipelines), and marketing of petroleum products. The larges ...

, mud weight is the density of the

drilling fluid In geotechnical engineering, drilling fluid, also called drilling mud, is used to aid the drilling of boreholes into the earth. Often used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also us ...

and is normally measured in pounds per gallon (lb/gal) (ppg) or pound cubic feet (pcf) .www.glossary.oilfield.slb.com
/ref> In the field it is measured using a

mud scale A mud balance, also known as a mud scale is a device used to measure the density (weight) of drilling fluid, cement or any type of liquid or slurry. Description and operation It consists of a graduated beam with a bubble level A spirit leve ...

mud balance A mud balance, also known as a mud scale is a device used to measure the density (weight) of drilling fluid, cement or any type of liquid or slurry. Description and operation It consists of a graduated beam with a bubble level A spirit leve ...

. Mud can weigh up to 22 or 23 ppg. A gallon of water typically weighs 8.33 pounds. In conventional drilling fluids,

barite Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate ( Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...

is used to increase the density. Although other additives such as

halite Halite (), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, p ...

(salt) or calcium carbonate can also be used. Mud weight can be decreased by dilution or

solids control Solids control is a process used in drilling rigs which use drilling fluid. It involves separating the "cuttings" (drilled material) from the fluid, allowing it to be recirculated or discharged to the environment. Background Drilling rigs are d ...

equipment such as an industrial

centrifuge A centrifuge is a device that uses centrifugal force to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities (e.g. cream from milk) or ...

, desilter, desander and shale shaker . Mud weight use to control the trapped fluids or gas in the formations by adding a hydro static pressure on them, increasing the mud weight = increasing the hydro static pressure. If the hydro static pressure increased over the formations pressure that will make a fracture in the formation leading to lose the mud to the formation, so adding loss circulation material like gel-flake or wood chips that can refill the gap and stop the mud loss. If the mud loss continues, then the hydro static pressure will decrease and flammable fluids and gas trapped under pressure will start leaking to the surface. This can lead to a potential blowout.

References

Drilling fluid {{Engineering-stub