EFFECTS OF CONTAMINANTS ON WATER-BASED DRILLING MUD

ABSTRACT

The oil and gas business is very risk and challenging requiring all operations to be done in a safe and economical way. Careful selection and application of drilling fluid are key factors that should be considered in order for a drilling operation to be successful. The primary objective of this study is to investigate the effects of contaminants on Water-Based drilling Fluid properties. From this experiment, it was observed that the presence of Sodium salt in the mud system increased the fluid loss into the formation. Also, while Apparent Viscosity, Gel Strength increased as the mass of the mud sample increased from 1g to 5g, the pH and Plastic Viscosity remained constant. However, the Yield point indicated little increase. With Cement as contaminant, it showed all rheological properties of the mud increased markedly, as the quantity of the cement sample used was increased from 1g to 5g and the pH did not change. Silica contamination did not show any significant effect on the nature of the drilling mud. In fact, as more amount of contaminant (Silica) was added, the closer the properties are to the blank sample that had no contaminant. The carbonate effect is largely on the Gel strength which decreased as the amount of added carbonate increased. The pH had no charges, which also meant carbonate kept the mud in its alkaline state, as it was the case with cement. In conclusion, the presence of a contaminant on the drilling mud either reduces or increases the rheological properties of the mud sample. This in turn affects the rate of penetration, its performance and also could pose serious drilling problems.