PDM Observations
• Motor stall will be obvious due to an increase in surface pressure.
Motor stalling should be avoided as it erodes the service life of the
motor.
• LCM can be pumped safely, though care should be taken that the
material is added slowly and evenly dispersed. The system should not
be slugged.
• Sand content in the drilling fluid should be kept to a minimum.
• Temperature limits are around 270°F to 130ºC, but higher temperature
stators have been developed.
• Pressure drop through the tool while working is typically around 50
psi to 800 psi.
• Allowable wear on bearings is of the order of 1mm - 8mm, depending
upon tool size.
• The tool should be flushed out with water prior to laying down.
In general, drilling fluids with a low aniline point can damage the rubber
stator. As a rule, the nailine point in oil based muds should be around
150°F (60°C). Usually, this is related to the aromatic content which should
be equal to or less than 10%. Contact the local supplier if there is any
doubt.
If a by-pass nozzle is fitted to a multi-lobe rotor, then it must be sized very
carefully to allow the motor section to develop the necessary power. Any
variation in flow for which the nozzle was inserted will compromise the
motor’s performance.
• Motor stall will be obvious due to an increase in surface pressure.
Motor stalling should be avoided as it erodes the service life of the
motor.
• LCM can be pumped safely, though care should be taken that the
material is added slowly and evenly dispersed. The system should not
be slugged.
• Sand content in the drilling fluid should be kept to a minimum.
• Temperature limits are around 270°F to 130ºC, but higher temperature
stators have been developed.
• Pressure drop through the tool while working is typically around 50
psi to 800 psi.
• Allowable wear on bearings is of the order of 1mm - 8mm, depending
upon tool size.
• The tool should be flushed out with water prior to laying down.
In general, drilling fluids with a low aniline point can damage the rubber
stator. As a rule, the nailine point in oil based muds should be around
150°F (60°C). Usually, this is related to the aromatic content which should
be equal to or less than 10%. Contact the local supplier if there is any
doubt.
If a by-pass nozzle is fitted to a multi-lobe rotor, then it must be sized very
carefully to allow the motor section to develop the necessary power. Any
variation in flow for which the nozzle was inserted will compromise the
motor’s performance.
