Drilling fluids are essential for the operation and productivity of petroleum wells. This study compares the efficiency of a salted water-based mud for which the viscosity has been enhanced with polymeric compounds with that of a new salted water-based mud containing palygorskite clay, which mainly functions as a viscosity enhancer. The experiment measured the density, apparent viscosity, plastic viscosity, yield point, American Petroleum Institute filtrate and pH of the samples. The results indicate that the rheological properties of the fluids containing greater amounts of palygorskite were not affected significantly by the addition of salt. However, when the concentration of palygorskite was low, the rheological behaviour of the samples was appropriate to the drilling operation only with lesser amounts of salt. In addition to its good rheological properties, the filtrate volume obtained for samples containing greater concentrations of palygorskite was lower, which suggests that the filtration properties at the bottoms of the wells were controlled appropriately.
