Drilling fluid
Aid for drilling boreholes into the ground
In geotechnical engineering, drilling fluid, also known as drilling mud or drilling slurry, is used to aid the drilling of boreholes into the earth. Used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also used for much simpler boreholes, such as water wells.
The two main categories of drilling fluids are water-based muds (WBs), which can be dispersed and non-dispersed, and non-aqueous muds, usually called oil-based muds (OBs). Along with their formatives, these are used along with appropriate polymer and clay additives for drilling various oil and gas formations. Gaseous drilling fluids, typically utilizing air or natural gas, sometimes with the addition of foaming agents, can be used when downhole conditions permit.
The main functions of liquid drilling fluids are to exert hydrostatic pressure to prevent formation fluids from entering into the well bore, and carrying out drill cuttings as well as suspending the drill cuttings while drilling is paused such as when the drilling assembly is brought in and out of the hole. The drilling fluid also keeps the drill bit cool and clears out cuttings beneath it during drilling. The drilling fluid used for a particular job is selected to avoid formation damage and to limit corrosion.
Composition
Liquid fluids are composed of natural and synthetic material in a mixed state, which can be of two types:
Aqueous; usually with substances added that control viscosity, along with lubricants, corrosion inhibitors, salts, and pH-control agents.
Oil; which could be usually using hydrocarbon oil,
Water-based drilling mud most commonly consists of bentonite clay (gel) with additives such as barium sulfate (baryte) to increase density, and calcium carbonate (chalk) or hematite.
The public source identifies “Drilling fluid” as aid for drilling boreholes into the ground. This brief keeps that definition visible, then builds a research path around Drilling, fluid and drilling.
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This entry incorporates text from “Drilling fluid” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.