Centrifuge
Centrifuge is a solid control equipment used on drilling rigs for removing fine and ultrafine particles from drilling fluid. Many solid removal equipment are used on the rigs, but centrifuge removes the finer particles that the other equipment like shale shaker or hydro-cyclones are not able to remove. Removing fine solids from mud system is important to be able to maintain mud properties within required specifications for drilling a well.
Not able to remove fine solids increases percentage of low-gravity solids (LGS) in the mud system, which adversely affects rate of penetration (ROP) and bit performance resulting in more trips for drilling the same footage. The mud becomes thicker and harder to pump, causing higher equivalent circulating density (ECD). Higher percentage of LGS also requires dilution, needing additional chemicals to maintain required mud properties.
Centrifuges use conical drums which rotate at high Revolutions Per Minute (RPM) to produce high G-force. Drilling fluid enters from one end and solids are separated from liquid phase due to high G-force to exit the bowl from the other end. Advanced centrifuges use variable frequency drive to be able to operate at varying speed to match required RPM of the bowl.