sodium carbonate — Oil & Gas Glossary
A chemical with the formula Na2CO3. It is called soda ash at the drilling rig and is used to treat most types of calcium ion contamination in freshwater and seawater muds. For cement contamination, sodium bicarbonate is used. Calcium ions from drilling gypsum or anhydrite, CaSO4, cause clayflocculation and polymerprecipitation and lower pH. A soda-ash treatment is appropriate for gypsum
Detailed Explanation
contamination because caustic soda, NaOH, is not needed to raise pH. This is also generally the case with hard water influxes into water muds.