Shale Shaker Screen

On today’s market the following screen cloths are available:

• Open area: Non blanked area of the Screen Cloth
• Conductance: Fluid that can pass through one sq/ft of screen cloth
• Usable screening area: The open area in sq/ft per screen
• Transmittance: Total fluid handling for one screen

The number of openings is the mesh size. All you do is count the number of openings in one inch of shaker screen. However, different wire diameter result in different screen aperture size. For a given mesh, the screen opening wholly depends upon the wire diameter used in the weaving cloth.

Example 1. 200mesh screen woven with a 0.04mm diameter wire will have an opening of 87 µ, (0.087mm).
d= (25.4 – (m x D))/m= (25.4 – (200 x 0.04))/200 = 0.087mm
Example 2. 200mesh screen woven with a 0.05mm diameter wire will have an opening of 77 µ, (0.077mm).
d= (25.4– (m x D))/m= (25.4 – (200 x 0.05))/m = 0.077mm

All these cloth types have the same mesh count and all have different aperture sizes.

• Open area: Non blanked area of the Screen Cloth
• Conductance: Fluid that can pass through one sq/ft of screen cloth
• Usable screening area: The open area in sq/ft per screen
• Transmittance: Total fluid handling for one screen

Cut points represent separation potentials of various particle sizes. Cut points of d16, d50, and d84, d100 are used

Example:
d84 for a 210 mesh screen = 94 microns
84% of the open area of the screen is composed of apertures less than 94 microns

• €, $, £ – Cost
• Screen Life
• Screen Capacity
• Separation Efficiency

• Overloading
• No load
• Blinding & plugging
• Wrong screen choice
• Corrosion
• Mechanical damage (Careless storage and handling, Hooking mesh cloth when removing cartridge shaker screens, Over tensioning hookstrip screens, Scraping screen surface to remove solids, Scoring pressure washer nozzles across the mesh surface)
• Poor solids transport/Abrasive solids (Screen design, Screen repairs, Blinding, Fluid properties)

Run the correct screens for the conditions
Don’t overload the screens
Stop no load conditions where possible
Don’t run adjustable shakers on high ‘G’ levels for extended periods
Clean shaker screens regularly
Repair burst panels
Diverter Plate Design

• Shaker Screen design ( Mesh Type )

Weave type and mesh size ( MG, TBC, TRSF, XR )
Frame non-blanked area ( API Specs )
Number of layers
Frame structural properties (Rigidity, Profile)

• Fluid properties ( Polymers )
• Formation (Clay or Heavy Loading )
• Shaker configuration
• Shakers Available
• Shaker Hand

• The finest available mesh should be fitted which can be run without loss of whole mud from the front of the shaker screens.
• As a general rule, the back two thirds to three quarters of the screen should be covered with mud. This allows for surges and rig heave when offshore.
• Angled single deck units of the Derrick Flo-Line type are designed to operate with a horseshoe shaped pond of mud, concave towards the front edge.

Use finest screens possible Unless specific drilling fluid requirements dictate otherwise, always use the finest screens possible without incurring mud carryover and with the shaker being configured in optimum set-up condition i.e. angle, pool depth etc.
Replace Damaged Screens Never allow torn screens to be used. As holes appear change and repair out at the first opportunity.
Proper Cleaning Never clean screens with brushes or sticks. The poor transportation requiring the use of brushes should be addressed at source. Always use appropriate cleaning solution. Never use water with an oil or synthetic based mud.
Screen Storage Shale shakers are the first and main defense against solids. The screens are fundamental in the operation. Do not store, transport or handle them inappropriately.
Correct supervision Shaker screen can significantly improve solids control efficiency.
Never By Pass Never by-pass the shaker except in an Emergency.
Maintenance Ensure the shaker components are in good order; rubber supports, tensioning mounts etc.
Try and run all the same mesh screens on the shaker.
Clean the shale shaker screens at each connection and inspect for damage.
Always clean the screens with appropriate fluid. Never use water with Oil based or synthetic muds.
Avoid using scrapers or brushes to clean off solids.
When signs of screen wear or holes are seen, remove and replace at the first convenient time. Do not tolerate any screen damage.
Repair shaker screens with the appropriate compound. Use an epoxy resin type for Oil and synthetic based muds.
Repair only until 10% mesh area is lost. Discard after this has been reached.