Investigation of the effects of carbonate contaminants on the rheological properties of drilling mud

Laboratory investigation of the effect of carbonate contaminant on the rheological properties of drilling mud based on Bingham plastic flow model was carried out. The rheological properties investigated were yield point, plastic viscosity, initial gel strength and ten‐minute gel strength. Eight samples of the same mud were used in the investigation. Equipment used in studying the rheological properties was a direct‐indicating viscometer. The result of the investigation showed that carbonate contaminant in drilling mud adversely increases the yield point and gel strength. Marginal increase in the plastic viscosity of the mud was also observed. The mud flocculated as the amount of carbonate increased.