Shale Shaker

Shale shaker is the first stage solids control equipment in drilling fluids system, it is the first line of defense for the whole mud system. The first line of defense for a properly designed solids control system is the shaker. Drilling shale shakers remove solids from drilling fluids as the mud passes over the surface of a vibrating screen. Particles smaller than the openings in the screen pass through the holes of the screen along with the liquid phase of the mud. Particles too large to pass through the screen are thereby separated from the mud for disposal. Without proper screening of the drilling fluids during this initial removal step, downstream equipment will experience reduced efficiency and effectiveness. The downstream desanders and oilfield desilters with hydrocyclones and/or drilling centrifuges (if employed) will simply be overloaded beyond their design capacity.

There are a number of commercial claims that indicate shakers can cut solids lower than 74μm, however, when it comes to the practical installation and use of solids control systems (i.e. relative to flow rates, drilling fluids viscosity, screen condition, volume of solids being managed, etc.), operators should conservatively assume 100μm as the performance limit.
 

Shaker Screens

Basically, a shale shaker 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 experience in manufacturing screens is considered.

If the system is appropriately set up with a scalping system and a fine screen system, the scalping screens must be sized just coarse enough to ensure that drilling fluids 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 fluids.

Relative to the use of shaker screens, it is the size of the screen openings, not the mesh number 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.