Feb. 28, 2022
A shaker screen consists of the following parts:
Much like a canvas for painting a screen has to be supported on a frame in order to do its job, this frame differs between manufacturers in both material and shape. Screen frames can be made from materials such as, square steel tubing, flat steel sheets, plastic type composites or they can just be supported on the ends with strips of steel (similar idea to a scroll). These frames consist of a rectangular shaped outer perimeter which is divided into small individual inner panels. These smaller panels differ in shape from manufacturer to manufacturer and have been known to come in shapes such as square, hexagonal, rectangular and even triangular.
These differing panel shapes are used in an attempt to reduce the quantity of panels on each frame but still provide maximum rigidity and support for the mesh attached to them. The purpose of reducing these panels is to maximize usable screening area as the walls of each panel get in the way of the mesh and prevent it from being used, this is known as "blanking". The non-blanked screening area of a shaker screen is widely used as a selling feature, the more screen surface you have available to work the more efficient your shaker becomes and therefore can handle a higher quantity of fluid.
Just like thread is woven together to create cloth, metal wire can be woven to create a metal cloth. Screen Mesh has evolved over many years of competitive screen manufacturing resulting in very thin yet strong cloth designed to maximize screen life and conductance as well as to provide a consistent cut point. To increase the conductance of a mesh screen you have to minimize the amount of material in the way, this is done by either reducing the wire diameter or weaving the cloth to produce rectangular openings. Rectangular openings increase the screens conductance while minimizing the effect on its cut point where as square openings provide a more consistent cut point but offer a lower conductance.
To maximize screen life most manufacturers build their screens with multiple layers of mesh over a very sturdy backing cloth to further protect the cloth against solids loading and wear. The multiple layers of mesh act as a de-blinding mechanism pushing near sized particles, which may get stuck in the openings, out of the mesh reducing blinding issues and keeping the screen surface available for use.
The binding agent is the material used to bind the mesh to the screen frame, it is designed to maximize adhesion to both materials while being able to handle high heat, strong vibration, abrasive cuttings and corrosive drilling fluids.
Plastic composite screens tend not to use adhesives but rather heat the mesh and melt it into the screen frame to form a bond.
One of the more recent advances in oilfield screen technology has brought us the "3D screen", this technology is an innovative method for increasing the screening area of a shale shaker without the need to build larger machines. When seen from the side these screens look like corrugated cardboard, having a flat bottom and wave like shapes on top. These waves are designed to increase the surface area of the screen panel by building up instead of out, thereby maximizing the surface area of the screen without the need to build larger shaker screens and in turn larger, heavier and more expensive shakers.
There are many claims in regards to the reason for the improved performance of these 3D screens such as:
Increasing the screening area of each panel transfers the load across more surface area and therefore the wear tends to be decreased in comparison to other screens.
The corrugated shape of the screens encourages solids to settle in the valleys of the screen, keeping the peaks of the screen available to process drilling fluid.
The tapered valleys, while moving under high G's, apply a compression force on the solids similar to wringing out a cloth to draw out liquid.
Increasing the surface area of the shaker allows the use of finer screens earlier in the drilling process while maintaining acceptable flow rates and penetration rate. Effectively removing harmful drilled solids before they can begin to wear out the solids control equipment.
Although the performance of these screens is quite impressive the only way to truly gauge the performance of any screen is to try it out and collect comparative data of your own.
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