Coarse shaker screen and solids removal
Coarse shaker screen is made of thicker wire with large opening screen cloth. It is mainly used to prevent large cuttings and clay. How operate coarse shaker screen during solids removal or drilling fluid process?
Coarse shaker screen general information
Drilling mud shale shaker
is set on overflow line will remove big cuttings and clay in drilling fluid. We call such shaker as “shaker screen protection coarse shaker" Even there is no clay the coarse shaker will be used to defend big cuttings or big shale mud block. This will help to protect screens finer than API 200.
The coarse shaker screen is made of thin metal wire. Compared to API 20 and API 40 screen such screen wire will be more easy to break. If there is hole on fine screen the big particles will flow into drilling fluid tank, while coarse shaker will get rid of such solid timely
Operation suggestion on coarse shaker
Many test told us the coarse shaker should be operated together with screen as fine as possible. When connected with main shaker mounted API 200 screen the API 80 or API 100 won't get more solids out of fluid. Obviously, in this range, shale will be broken to smaller particles finer than 74 microns or coarse shaker screen break cuttings down to let linear motion shaker break cuttings. Thus will decrease solid quantity. Coarse shaker should be used to prevent big cuttings hitting fine screen cloth.
The coarse shaker can bring clay into drilling fluid even mounted with API 20. So we'd better use coarse screens. The screen protection coarse shaker should be operated together with elliptical circle motion shaker. The clay has to be removed before transferring to screen cloth.
Factors affecting coarse shaker use or not
If the screen panel can be set with downward angle also with slid plate the gravity will help clay removal. If the shaker is traditional unbalanced elliptical shaker the fixed downward angle will meet requirements of clay deliver. If the shaker deck is even the shaker will produce a exact vertical downward force to overcome clay adhere force then remove solids
If shaker screen
is not able to separate solid out the clay will adhere on screen panel steadily. If change drilling fluid to decrease clay following down ground. For shaker with high gravity, it's easy to get rid of clay. However, we'd better use coarse shaker screen to removal large cuttings, to avoid any trouble resulted in ignoring screen broken
In short, the clay solid should be removed from drilling fluid before fluid arriving at shaker. The coarse shaker and screen is helpful and effective enough. For more information or any question please contact Aipu freely