Threat · Flow Assurance
Mineral Scale
Mineral deposits that precipitate from produced water, such as calcium carbonate, barium and strontium sulfate, calcium sulfate, halite and iron sulfide.
What it does
Carbonate forms as CO2 leaves the water when pressure drops; mixing incompatible waters, such as injected seawater with formation water, deposits barite. Threshold inhibitors work at very low concentrations, by continuous injection or squeeze.
Basics
| Common types | Calcite, barite, celestite, gypsum, halite, iron sulfide |
| Prevention | Threshold inhibitor, continuous or squeezed |
| Removal | Acid for carbonates, mechanical for sulfates, fresh water for halite |
| Watch for | Barite can carry naturally radioactive radium |
Common failures
- Tubing, pump or flowline restricted by scale
Troubleshooting
- Symptom
- Rate falls as water cut rises
- Likely cause
- Scale building where pressure drops
- What to check
- Analyze the water and the deposit, then set up a threshold inhibitor program