Threat · Flow Assurance
Asphaltenes
The heaviest fraction of the crude, which can drop out as a dark, sticky solid when pressure falls or incompatible oils are mixed.
What it does
Deposits can form in the tubing, valves, separators and flowlines. Inhibitors only work if they are in the oil before precipitation starts; existing deposits are removed with aromatic solvent soaks, such as xylene, or mechanically.
Basics
| Triggers | Pressure drop toward the bubble point, mixing of incompatible crudes, gas lift |
| Prevention | Asphaltene inhibitor, continuous or squeezed |
| Removal | Aromatic solvent soaks, pigging, hydroblasting |
| Good practice | Test each inhibitor on the specific crude |
Common failures
- Choke, valve or tubing restricted by asphaltene deposits
Troubleshooting
- Symptom
- Production drops after a change in pressure or a new crude is mixed in
- Likely cause
- Asphaltene precipitation
- What to check
- Sample the deposit, solvent soak and start an inhibitor tested on that crude