Indications show that drilling mud shale
shaker can achieve solid cuts lower than 74μm, however, when it comes to the
practical installation and use of solids
control system ( i.e. relative to flow rates, drilling fluid viscosity, shaker
screen condition, volume of solids being managed, etc. ) operators should
conservatively assume 100μm as the performance limit.
Basically, a screen acts as a “go/no-go” gauge: either a particle is small
enough to pass through the screen or it is not. Screening surfaces used in
solids control equipment are generally made of multi-layered woven wire screen
cloth and are the “heart and soul” of the shaker. Fundamentally, the quality of
a shaker is defined by the quality of screens it utilizes. When selecting a
solids control system, it is important that the quality of the screen
manufacturing and level of experience by the in manufacturing screens is
considered.
If the system is appropriately set up with a scalping system and a fine shale
shaker screen system, the scalping screens must be sized just coarse enough to
ensure that drilling fluid does not sheet off the shaker ( i.e. whole mud losses
). This happens when the scalping screen is too fine to allow the drilling
fluids to pass into the solids control system’s dirty tank. Typical scalping
screen configurations for HDD applications range from 50 mesh ( API 50 ) to 120
mesh ( API 100 ). Typical fine screen configurations range from 160 ( API 120 )
to 200 mesh ( API 170 ). The API 13C classification is gaining traction in the
HDD industry as more contractors focus on the micron cut point they are trying
to achieve in their fluid.
Relative to the use of shaker screens, it is the size of the screen openings,
not the mesh count that determines the size of the particles separated by the
screen. It is because of this fact that HDD system users should compare and
specify screens based on their API 13C designation.
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