Soft acidizing

Concept : long duration injection from well head of a strongly diluted acid solution (=<0,5%).
Aim : dissolving of scale peaks affecting casing roughness and subsequent friction losses.
Outcome : Achievement of substantial productivity/injectivity gains at costs lower than those of conventional acid jobs .

Equipments – layout

  • Production well : soft acidizing submersible equipment in hole
  • Acid injection via the Auxiliary Injection Tubing (AIT) downhole chemical injection line.
  • Possibility of mixing acids and chemical inhibitors.
  • Injection from surface with no interruption of the chemical inhibition process.
  • Continuous recording / monitoring of flowrates and well head pressures and temperatures.
  • Injection well : soft acidizing with no interruption of geothermal fluid circulation and of the chemical inhibition process.

Acid selection

  • Efficiency pilot tests of candidate acids on scale samples.
  • Compatibility tests with utilized inhibiting agents.
  • Compatibility tests with iron sequestrant additive.
  • Compatibility tests with sensitive materials of exposed equipments.


  • Sharp decrease of well head injection pressures (6 bars at 225 m²/h).
  • Significant upgrading of the injectivity index and of nominal exploitation rate.
  • Less than one year pay back time.
Monitoring of injection pressure and of injectivity index.

Monitoring of injection pressure and of injectivity index.