Efficient Drill Cuttings Transfer with Progressive Cavity Pumps

Progressive cavity pumps (PCPs) have a unique advantage in handling solids, liquids, gases and a combination of all three. In applications in which the solid content is high and the liquid amounts are low, as long as the sealing lines are minimally lubricated, the solids handling capability of PCPs has proven reliable and economical compared to alternate technologies, such as conveyors or augers.

Drill cuttings transfer is one area in which the progressive cavity pump is widely used and has helped end users reduce their operating costs. Individual PCP manufacturers should be contacted to see if their pumps can be used successfully in this type application and can produce reduced operating costs.

The Drilling Process

During the drilling process, clean drilling mud is pumped down through the tubing and serves as the driver for positive displacement motors. As it travels down the pipe, pressurizes the motor, goes through the nozzles of the drill bit and returns back to the surface through the annulus, the drilling mud provides lubricity and cooling to the rotating parts and flushes out the rock cuttings.

The viscosity and weight of the mud is critical for an efficient rate of penetration depending on the geologic formation. Also important is the selection of the bit and the fluid velocities of the drilling mud returning back to the surface as it flushes the cuttings from the bottom hole. Several types of drill bits are available, such as polycrystalline diamond compact bits and rock bits, which require the motor to rotate at a certain rpm. The higher rpm diamond bits will generate higher flush velocities where as the rock bits used at lower rpms will have slower linear velocity of the fluid in the annulus.