Desander

Desander is a solids-control device used in oil and gas drilling to remove sand-sized solids from drilling mud. It is typically part of a mud circulation and solids-control system, installed after the shale shakers and prior to the mud storage tanks, to reduce abrasive wear on pumps, valves, and downhole equipment.

Principle and design: A desander relies on hydrocyclone technology. Drilling mud enters tangentially into a cluster of hydrocyclones inside a pressure vessel. Centrifugal forces within the cyclones cause heavier solids to report to the underflow, which is discharged to the solids-handling stream, while the clarified mud exits via the overflow back to the mud system. The number and size of hydrocyclones determine the performance and the cut size, i.e., the size of solids removed.

Design and configuration: A desander typically consists of a cyclone cluster housed in a pressure-rated vessel, with inlet and outlet manifolds. It is driven by the same mud pump that supplies other solids-control equipment and is often used in combination with desilters (for finer solids) as part of a complete solids-control train.

Operation and maintenance: Proper operation requires appropriate feed pressure and flow rate; excessive flow can erode cyclones, while underflow reduces solids removal. Regular inspection of cyclone liners, gaskets, and connections is advised, and periodic cleaning ensures consistent performance. The unit is designed to remove larger, sand-sized particles rather than fines.

Applications: Desanders are standard on land and offshore drilling rigs and are used to protect pumps, valves, and downhole equipment. They are also employed in other fluid-processing industries where sand or coarse solids must be removed from suspensions.