Desanders and Desilters are both composed of couples of hydrocyclones and a small fine-mesh shale shaker which is used for handling hydrocyclone underflow and recycling drilling fluid. Desanders are used for separating solids phase particles whose diameter is between 44~74μm;Desilters are used to separate solids phase particles whose diameter is between 15~44μm.The following form 3 lists the working scope of common hydrocyclones.
|Form 3 Working Scope of Single Hydrocyclone|
From form 3 we know that desanders can be used as the second equipment after shale shaker to separate solids phase particles,and desilters should be used as the third equipment in solids control system.
In order to satisfy all the requirements of handling drilling fluid,desanders and desilters must be composed of several hydrocyclone cones.
Liquid Inlet Pressure
To ensure the normal work of hydrocyclones,the liquid inlet pressure must be around 0.25~0.35MPa.As the desilters have more hydrocyclone cones and longer manifolds,the liquid inlet pressure should be bigger;As the desanders have less cones and shorter manifolds,the liquid inlet pressure should be smaller.
Inlet pressure mainly depends on the reasonable matching of centrifugal pumps,so choosing a centrifugal pump is of vital importance.A centrifugal pump usually head up to 40mH2O and its handling capacity can be equals to that of desander and desilter's which can satisfy operating requirements.Meanwhile,in order to reach the best combination, the maximum handling capacity of centrifugal pumps must be taken into consideration when choosing desanders and desilters.
Combination of Desanders and Desilter
The time of using these two equipments has no strict limits,when drilling at shallow and soft stratum,these two equipments must be used together as the content of large cuttings is high in drilling fluid;When drilling at deep and hard stratum,if fine-mesh shale shaker is adopted,desilters can be used to handle drilling fluid directly not only because it has slightly impact on the quality of purification of drilling fluid but also very economical.