Bentonite: Density and Yield Properties
Bentonite is the clay that gives water based mud its body: a swelling smectite that builds viscosity and a filter cake from a remarkably small dose.
Solid SG about 2.6, API yield at least 90 barrels per ton
| Density of solid clay | SG about 2.6 |
| Bulk density, powder | 800 to 960 kg per cubic meter |
| API yield specification | at least 90 bbl of 15 centipoise mud per ton |
| Typical dose | 15 to 25 kg per cubic meter of mud |
| Swelling | sodium bentonite swells many times its dry volume in fresh water |
Notes for design and site
Yield, not density, is what you buy bentonite for: a ton of good Wyoming sodium bentonite turns ninety plus barrels of fresh water into usable mud. It sulks in salty or hard water, where it barely swells, which is why seawater muds lean on attapulgite or polymers instead. Prehydrate it in fresh water before it meets contaminated systems.
Related Calculators and Reference
- Mud Weight and Pressure Gradient Calculator: convert these densities into downhole pressures.
- Equivalent Circulating Density: what the formation feels while pumping.
- American Petroleum Institute: source of drilling fluid specifications.