Pm, Pf and Mf are values indicating the alkalinity of drilling mud and the following is meaning of each value.
Pm stands for “phenolphthalein end point of the mud” and it indicates quantities of Potassium Hydroxide (KOH), caustic soda, cement, etc., in the water base mud. The Pm refers to the amount of acid required to reduce the pH of mud to 8.3. The Pm test includes the effect of both dissolved and non-dissolved bases and salts in drilling fluid. Especially in lime mud, Pm is used to determine the ratio of insoluble lime to soluble lime in the filtrate.
Pf stands for the phenolphthalein alkalinity of the mud filtrate. Pf is different from the Pm because it tests the affect of only dissolved bases and salts. However, Pm includes the effect of both dissolved and non-dissolved bases and salts in drilling mud. Continue reading