A mud motor (or drilling motor) is a progressive cavity positive displacement pump (PCPD) placed in the drill string to provide additional power to the bit while drilling. The PCPD pump uses drilling fluid (commonly referred to as drilling mud, or just mud) to create eccentric motion in the power section of the motor which is transferred as concentric power to the drill bit. The mud motor uses different rotor and stator configurations to provide optimum performance for the desired drilling operation, typically increasing the number of lobes and length of power assembly for greater horsepower. In certain applications, compressed air, or other gas, can be used for mud motor input power. Normal rotation of the bit while using a mud motor can be from 60 rpm to over 100 rpm.
Based on the principle developed by Rene Moineau, the theory states that a helical rotor with one or more lobes will rotate eccentrically when the stator contains more lobes than the rotor. The flow of the fluid transmits power allowing the assembly to rotate and turn the bit.
Extremely hard rock formations can be drilled with motors using diamond or polycrystalline diamond compact (PDC) bits.
High penetration rates can be achieved since rotation speeds are high.
Will allow circulation of the borehole regardless of the horsepower or torque produced by the motor.
Post time: Jun-03-2020