Bentonite is an absorbent aluminium phyllosilicate clay consisting mostly of montmorillonite. It was named by Wilbur C. Knight in 1898 after the Cretaceous Benton Shale near Rock River, Wyoming.
The different types of bentonite are each named after the respective dominant element, such as potassium (K), sodium (Na), calcium (Ca), and aluminium (Al). Experts debate a number of nomenclatorial problems with the classification of bentonite clays. Bentonite usually forms from weathering of volcanic ash, most often in the presence of water. However, the term bentonite, as well as a similar clay called tonstein, has been used to describe clay beds of uncertain origin. For industrial purposes, two main classes of bentonite exist: sodium and calcium bentonite. In stratigraphy and tephrochronology, completely devitrified (weathered volcanic glass) ash-fall beds are commonly referred to as K-bentonites when the dominant clay species is illite. In addition to montmorillonite and illite another common clay species that is sometimes dominant is kaolinite. Kaolinite-dominated clays are commonly referred to as tonsteins and are typically associated with coal.
Bentonite Specifications
Parameters
API 13 A Section 9
Viscometer dial reading at 600 rpm
30 min
YP / PV Ratio
3 Max
API Fluid Loss
15 ml Max
Residue > 75 µm
4% Max
Advantage
. Bentonite extracts the drill cutting from around the bit which is then floated to the surface.
· Bentonite seals the drill hole against seepage and prevents wall cavities and leakages.
· Bentonite (Drilling mud) served to cool and lubricate the drill bit.
· Bentonite form slurry with leakages that is pumped through drill stem and out through drill bit.
Applications
. Drilling mud (gel) is crucial in the extraction of drill cutting during the drilling processes.
· Drilling mud (gel) is a major component in well drilling process.
· Another conventional use of bentonite is as a mud constituent for oil and water well drilling. Its roles are mainly to seal the borehole walls, to remove drill cuttings and to lubricate the cutting head.