Definition - What does Positive-Displacement Motor mean?
A Positive-Displacement Downhole Mud Motor is a downhole tool which is used during field drilling operations to provide rotational power to drill bits and other downhole tools. It is mainly used in directional drilling operations. The rotational motion to a drill bit is provided by the drilling fluid which is pumped into the wellbore with the help of a positive displacement motor that converts the hydraulic power of the fluid into mechanical power so as to rotate the bit.
Petropedia explains Positive-Displacement Motor
Positive-displacement motors are also known as downhole motors or simply mud motors. Such types of positive displacement motors have downhole turbine motors which are powered by drilling fluid. They are connected to the drill bits and allow the rotation of the drill bit and other downhole drilling equipment and tools without the need for rotating the drill strings located above the equipment. Such mud motors are extensively used in directional drilling, performance drilling, straight hole drilling, under reaming, milling and coring operations.