Drilling Fluid Contamination: Carbonate/ Bicarbonate
One of the most unrecognised types of contamination is that due to Carbonate and Bicarbonate ions. Usually such contamination is gradual, resulting in increased gel strengths and yield point. It is often incorrectly diagnosed as increased solids but, in this case, application of costly thinners have little, or no effect.
Sources of Carbonates
- C02 from drilled formations or air ingress.
- Thermal degradation of organic additives
- Over treatment with soda ash or sodium bicarbonate
- Carbonate formations
Diagnosis by Analysis of Mud Alkalinity