Methods and apparatus for measuring the erodability of drilling fluid deposits

摘要

Methods of measuring the erodability of drilling fluid deposits and the shear stress required to remove drilling fluid deposits formed on the walls of a well bore are provided. The methods basically include introducing a drilling fluid into a test apparatus which simulates a permeable section of a well bore. Drilling fluid deposits are caused to be formed on the walls of the permeable section, and the drilling fluid is circulated through the permeable section at progressively increasing flow rates to determine the pressure drop below which no appreciable erosion of the drilling fluid deposits takes place which corresponds to the minimum shear stress required to erode the deposits. The erodability of the drilling fluid which is inversely proportioned to the minimum shear stress can also be determined. Apparatus for carrying out the methods is also provided.