OPTIMIZATION OF INHIBITIVE WATER-BASED MUD USING CALCIUM CARBONATE

The need for shale inhibitors while formulating inhibitive drilling mud system is increasing due to the global demands for energy and with the breakthrough in recovery of fossil fuels from shale beds, more and more shale sections would be drilled. KCl/polymer mud, an inhibitive drilling mud system was optimized by the addition of calcium carbonate to improve the mud deliverability in areas such as; weighting agent, bridging agent, filtration control agent and inhibitor. A 0.5 molar concentration of potassium chloride was used in the preparation of the inhibitive mud. Calcium carbonate was added in specific amount by weight and the resultant formulation was subjected to the following mud property tests: density, filtration test, rheological property test and pH value test. The formulated mud system has good and appreciable values in the mud properties tested. The mud weight increased significantly with the addition of more calcium carbonate with no increase in solid content of the mud. The mud ph and filtration properties were not affected by the variations in the concentrations of calcium carbonate.