Citric acid

Reduce pH, precipitate soluble calcium, and sequester iron

Schlumberger Oilfield Services

Citric acid is used to reduce pH and remove calcium when drilling cement, to reduce the potential of crosslinking polymers (xanthan and others) from iron, and to prevent fish-eyes when mixing polymers. An organic acid, citric acid is less reactive compared with sulfuric or hydrochloric acid, thereby being somewhat safer to handle.

  • Widely available, multifunctional acid
  • Reduces pH and removes calcium to pretreat or remedy cement contamination
  • Sequesters soluble iron to prevent polymer crosslinking
  • As compared to alternative acids, less reactive and safer to handle—i.e., better health, safety and environmental considerations
Typical Physical Properties
Typical Physical PropertiesPhysical appearance Opaque to white granules
Typical Physical PropertiesSpecific gravity 1.542
Typical Physical PropertiesSolubility at 68 degF [20 degC] 169 g/100 mL water


  • More expensive than other more reactive acids
  • Supply is occasionally limited
  • Requires higher treatments than alternative chemicals