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PREFACE
P-1
General Information
Application of the Consistometer
Cements have numerous applications in the drilling, completion, work-over, and abandonment of
wells. For each application, the cement is designed with special properties and is given additives
that provide predictable slurry density, volume, viscosity, compressive strength, and thickening
time. Thickening time, or the time a cement slurry remains able to be pumped into the well, is the
most critical properties in designing a cement. A short thickening time is desired, while maintaining
the special properties of the cement's design. The thickening time of a cement can be measured in a
laboratory by testing a sample of the cement slurry in a Pressurized Consistometer. The elapsed
time between an initial application of pressure and temperature on the slurry sample and the
development of 100 Bearden units of consistency (Bc) is the thickening time for the sample at a
particular specification test schedule [Table 8.2, API Spec 10(1)].
Test Procedure
Briefly, the test procedure for the Model 8040D10 Pressurized Consistometer entails the
preparation of the slurry sample, placing it in the Consistometer, applying pressure and increasing
temperature according to the API Spec 10 Code Schedule(1), and recording the consistency of the
slurry as a function of time. Details of the procedure are contained in the Specification.
Description of Apparatus
The Pressurized Consistometer incorporates a rotating, cylindrical Slurry Cup equipped with a
stationary paddle assembly enclosed in a pressure chamber designed for a working pressure of 275
MPa (40,000 psi) at a maximum temperature of 315°C (600°F). (An air-operated hydraulic pump
generates pressure to the cylinder assembly.) The hydraulic system incorporates a reservoir, piping,
valves and filters. Heat is supplied to the chamber by a 5000-watt, internal, tubular heater
controlled by the automatic temperature control system program. Thermocouples are provided for
determining the temperatures of the oil bath and cement slurry.
The programmable temperature controller will automatically control the rate of temperature rise of
the slurry (i.e. temperature gradient). When the slurry reaches the desired maximum temperature,
the controller will hold the slurry temperature at that level. Pressure settings are maintained
through the control of a pressure release valve and air pressure available to the pump.
The slurry container is rotated at a constant speed of 150 +/- 15 rpm by a Magnetic Drive (Drawing
8-229). Drive torque is transmitted from a set of outside drive magnets, through a non-magnetic
housing, to permanent magnets attached to the rotating shaft within the cylinder. Permanent, rare
earth magnets are used to ensure high torque and a long magnetic-field life.
REFERENCES
American Petroleum Institute; API Specification for Materials and Testing for Well Cements, Latest Edition; Dallas,
TX.
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