Desander is the second equipment on solids control system which is used to separate solids phase particles with diameter bigger than 47um. Desander functions as reduce the downstream loads of desilter and improve processing efficiency of desilter. In high speed drilling, particularly in superficial zone with loosen clay layer, bigger diameter drills are used, so more cuttings produced. In this condition, drilling cuttings may be produced with excessive amount and desander then need to install in the front of the steps before desiltings. As long as desander here separates bigger particles in the high concentration fluids, desilter would able to process the overflow drilling mud form the desander. If the drilling speed is not so fast and only process half ton of drilling cuttings, desilter could process the whole drilling mud in the circulation system, and under this condition, desander cam be shut.
 

 

Drilling mud is not processed by desilter but desander is necessary. However, in viscous oil based drilling mud (deep drilling), oil phase may be brought by the desander overflow, so non weighted water based drilling mud can be processed in weighed drilling mud, because it will get rid of big mount of barite. In total, to non-weighted drilling mud processing, desilter must be used. 

 

As for these drilling mud with big amount of barite, desiler and desander (with micro cyclone) are all not allowed to be applied and can only be processed by other solids control units. Because, the diameter of desander and barite is similar to each other. Most of the barite diameter is within 2-44um, a little part is within 44-74 um, and only 8% to 15% drilling mud contains barite diameter within 0-2 um. 
 

 

The desander separation points are mostly within 2-44um, while the desiler separation points are within 10m-15um. Accounting from most of the barite diameter are above of the diameter of 10-15um, they will be discharged together with fine and thick diameter particles.