The Methylene Blue Dye Test, (MBT), is used to determine the Cation Exchange Capacity of the solids present in a water base drilling mud. Only the reactive portions of the clays present are involved in the test and materials such as Barite, Carbonates, and Evaporitesdo not affect the results of the test, since these materials do not adsorb the Methylene Blue 
•For Bentonite based mud systems, the MBT provides an indication of the amount of reactive clays which are present in the drilling mud solids and for Bentonite free, water based mud systems, the MBT reflects the reactivity of the drilled solids. The test cannot distinguish between the type of clays but, if a reactivity for the drilled solids is known or assumed, it can be used to determine the amount of Bentonite present in the Bentonite based systems Test Procedure: •Using the completely filled, 3 ml syringe, measure 2.0 ml of mud sample to be tested into the Erlenmeyer flask containing 10-15 ml of distilled water. •Add 15 ml Hydrogen Peroxide and 1 ml of 5N Sulfuric Acid. Swirl or stir as required to mixed the solution •Boil gently for approximately 10 minutes, and dilute with 20 ml fresh water. Test Procedure: •Add Methylene Blue Dye in 1.0 ml increments. After each dilution, swirl the flask and stir vigorously for at least 20 seconds, and remove a drop of sample on the end of the stirring rod. •Apply the drop to a piece of filter paper making the drop with the amount of Methylene Blue added between each increment. The approximate end point is reached when a blue ring spreads out from the blue spot on the filter paper. •At this point, without further addition of Methylene Blue, swirl the flask an additional 2 minutes, and place another drop on the filter paper. If the blue ring is again apparent, the end point has been reached. •If the ring did not appear, continue with the Methylene Blue increments until a blue ring permanently forms after two additional minutes of swirling Note: For increased accuracy, 0.5 ml increments may be used as the end point is approached. The blue ring is more apparent on the reverse side of the filter paper from which the drop is placed Calculations: Note:Thereare 2 different strengths of Methylene Blue dye that is used todetermine the Equivalent Bentonite Content. One will have to determine which strength of dye the chemical testing company is supplying •Stronger Strength of Methylene Blue: –kg/m3Reactive Clay ( Equivalent Bentonite Content) = 14.25 X ml Methylene Blue ml of Mud Sample –lb/bbl Reactive Clay ( Equivalent Bentonite Content) = 5 X ml Methylene Blue ml of Mud Sample •Weaker Strength of Methylene Blue –kg/m3Reactive Clay ( Equivalent Bentonite Content) = 10 X ml Methylene Blue ml of Mud Sample –lb/bbl Reactive Clay ( Equivalent Bentonite Content) = 3.5 X ml Methylene Blue ml of Mud Sample
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•For Bentonite based mud systems, the MBT provides an indication of the amount of reactive clays which are present in the drilling mud solids and for Bentonite free, water based mud systems, the MBT reflects the reactivity of the drilled solids. The test cannot distinguish between the type of clays but, if a reactivity for the drilled solids is known or assumed, it can be used to determine the amount of Bentonite present in the Bentonite based systems Test Procedure: •Using the completely filled, 3 ml syringe, measure 2.0 ml of mud sample to be tested into the Erlenmeyer flask containing 10-15 ml of distilled water. •Add 15 ml Hydrogen Peroxide and 1 ml of 5N Sulfuric Acid. Swirl or stir as required to mixed the solution •Boil gently for approximately 10 minutes, and dilute with 20 ml fresh water. Test Procedure: •Add Methylene Blue Dye in 1.0 ml increments. After each dilution, swirl the flask and stir vigorously for at least 20 seconds, and remove a drop of sample on the end of the stirring rod. •Apply the drop to a piece of filter paper making the drop with the amount of Methylene Blue added between each increment. The approximate end point is reached when a blue ring spreads out from the blue spot on the filter paper. •At this point, without further addition of Methylene Blue, swirl the flask an additional 2 minutes, and place another drop on the filter paper. If the blue ring is again apparent, the end point has been reached. •If the ring did not appear, continue with the Methylene Blue increments until a blue ring permanently forms after two additional minutes of swirling Note: For increased accuracy, 0.5 ml increments may be used as the end point is approached. The blue ring is more apparent on the reverse side of the filter paper from which the drop is placed Calculations: Note:Thereare 2 different strengths of Methylene Blue dye that is used todetermine the Equivalent Bentonite Content. One will have to determine which strength of dye the chemical testing company is supplying •Stronger Strength of Methylene Blue: –kg/m3Reactive Clay ( Equivalent Bentonite Content) = 14.25 X ml Methylene Blue ml of Mud Sample –lb/bbl Reactive Clay ( Equivalent Bentonite Content) = 5 X ml Methylene Blue ml of Mud Sample •Weaker Strength of Methylene Blue –kg/m3Reactive Clay ( Equivalent Bentonite Content) = 10 X ml Methylene Blue ml of Mud Sample –lb/bbl Reactive Clay ( Equivalent Bentonite Content) = 3.5 X ml Methylene Blue ml of Mud Sample