The most common mistake in calcite control is feeding the right product at the wrong point. The scale inhibitor has to reach below the depth where scale starts to form. The standard way to do this is continuous dosing through capillary tubing run into the well.
How does the system work?
Capillary tubing made of stainless steel or a corrosion-resistant alloy is run into the well through a sealed wellhead entry. Its end usually carries a sinker bar and a check valve. A dosing pump at the surface continuously pushes the inhibitor through the tubing below the flash depth, and the chemical reaches the scaling zone as it rises with the fluid.
How is the injection depth determined?
Flash depth is calculated from wellhead pressure, reservoir temperature, the downhole temperature–pressure profile and the gas content of the fluid. The injection point is placed a safety margin below it. When operating conditions (wellhead pressure, flow) change, the flash point moves as well, so the depth should be reassessed periodically.
Dose optimisation
The starting dose is set from fluid analysis. Calcium retention, residual inhibitor and pressure data at the wellhead are then tracked and the dose adjusted step by step. The aim is the lowest economic dose that prevents scale: overdosing raises cost, underdosing brings the scaling risk back.
Common problems
- Capillary plugging: product stability at high temperature and continuous flow are essential.
- Pump failure or empty chemical tank: even short interruptions can start scaling; alarms and a standby pump are recommended.
- Tubing end left at the wrong depth: recalculation is needed when conditions change.
| Component | Function |
|---|---|
| Capillary tubing | Carries the chemical below the flash depth |
| Sinker bar and check valve | Keep the tubing straight and prevent backflow |
| Dosing pump | Continuous feed at a steady, adjustable rate |
| Chemical tank and level alarm | Ensures uninterrupted dosing |
Frequently asked questions
Can dosing be done without capillary tubing?
Surface dosing may be enough for surface equipment and the reinjection line; for downhole calcite scale the chemical must reach below the flash point.
Will the scale inhibitor plug the capillary?
The risk is low when a product that is stable at high temperature and compatible with the fluid is selected; selection takes these conditions into account.
Does Biyopol install the equipment?
Biyopol provides the product, the injection point recommendation, dose optimisation and monitoring support. Equipment installation is planned with the site team or a service company.
Related guides
- Geothermal power plant chemicals (overview)
- Calcite scaling in geothermal wells
- Silica and metal silicate scaling
- Corrosion in geothermal systems
- Heat exchanger and ORC fouling
- Scaling in reinjection lines and wells
- Geothermal heating and greenhouse systems
- Sulphide scales (stibnite, iron sulphide)
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