ABSTRACT

During drilling operations, the drilling fluid filters into formations of different components it comes in contact with foreign materials present in these formations which are classified as contaminants and these contaminants have effects on the rheological properties of the mud thereby affecting its ability to perform it functions. When drilling with water-based muds (WBM), significant fluid loss volumes from the mud into the formation can have adverse effects not just on the mud and its properties but also on the stability of the wellbore.

Experiments were carried out to check the effect of four contaminants (salt) in the rheological and filtration properties of water base mud. These salts are Sodium carbonate, Sodium Chloride, Magnesium Carbonate and Calcium Carbonate.

From our results, it was shown that sodium carbonate has the greatest effect on drilling mud rheology. It increases mud rheological properties as its composition increases most especially the yield point. Also, it enhances mud filtrate loss.