Soda ash | SLB

Soda ash

Sodium carbonate

Schlumberger Oilfield Services

Soda ash is the common name for sodium carbonate (Na2CO3). It is a weak base that is soluble in water and dissociates into sodium (Na) and carbonate (CO3) ions in solution.

Calcium is present in many makeup waters and formations. It can cause flocculation of the mud, resulting in increased rheology, gel strengths, and fluid loss. High-filtrate calcium causes precipitation of calcium-sensitive additives, such as POLY-PLUS high-molecular-weight liquid clay inhibitors and RINGFREE polymeric thinners, which are the most sensitive. Cellulosic polymers are only slightly calcium-sensitive and tolerate moderate levels of filtrate calcium.

  • Widely available and economical source of carbonate ions to precipitate calcium while increasing pH
  • Concentrate chemical; effectively removes calcium in most drilling fluids at small treatment levels



Typical Physical Properties
Typical Physical PropertiesPhysical appearance White powder
Typical Physical PropertiesSpecific gravity 2.51
Typical Physical PropertiespH (1% solution) 11.4
Typical Physical PropertiesSolubility in water 572 degF [300 degC], 51 g/100 mL at 86 degF [30 degC]

Toxicity and handling

Bioassay information is available upon request. Handle as an industrial chemical, wearing protective equipment and observing the precautions described on the transportation and safety data sheet.

Soda ash is an alkaline material that can cause irritation to eyes, skin, or respiratory tract. Soda ash should be added slowly to the mud system either by mixing through the hopper or chemical barrel. Do not mix soda ash with other chemicals, especially caustic soda or lime. When using a chemical barrel, mix soda ash into a full barrel of freshwater and provide adequate agitation.

Packaging and storage

Soda ash is a globally available commercial chemical and is packaged in 100-lb [45.4-kg] and 50-lb [22.7-kg], multiwall, paper sacks. Store in a dry area away from water or acids.


  • Increases pH and should not be used to treat cement contamination or higher pH fluids; less soluble at high pH.
  • Overtreatment results in carbonate contamination; even minor amounts of excess carbonate ions can cause large increases in yield point, gel strengths, and fluid loss.