Density of Diesel and Base Oils
Diesel and synthetic base oils are lighter than water, which sets the floor for oil based mud density and drives buoyancy corrections in every fluid column that contains them.
About 850 kg per cubic meter, 7.1 ppg
| Diesel fuel | 820 to 860 kg per cubic meter |
| In ppg | about 7.0 to 7.2 ppg |
| Typical synthetic base fluids | 780 to 820 kg per cubic meter |
| Pressure gradient | about 0.37 psi per foot |
| Behavior with temperature | expands and lightens noticeably when hot |
Notes for design and site
An unweighted oil mud cannot reach even the freshwater gradient, so barite does the lifting from a lower starting point. The strong thermal expansion of oils also matters: a hot well makes the annulus fluid lighter than the mud engineers surface measurement suggests, and deepwater cold does the reverse in the riser.
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.