The types and quantities of solids present in drilling mud solid control system

The types and quantities of solids (insoluble components) present in drilling fluids systems play major roles in the fluid’s density, viscosity, filter-cake quality/filtration control, and other chemical and mechanical properties. The type of solid and its concentration influences mud and well costs hole stability, These, in turn, influence the service life of bits, pumps, and other mechanical equipment.

Drilled solids, consisting of rock and low-yielding clays and addictive polymer, are incorporated into the mud continuously while drilling. To a limited extent, they can be beneficial before excess the tolerated concentration. Different mud densities require different strategies to maintain the concentration of drilled solids within an acceptable range. Whereas low mud densities may require only mud dilution in combination with a simple mechanical separator, high mud densities may require a more complex strategy:
chemical treatment to limit dispersion of the drilled solids (e.g., use of a shale inhibitor or deflocculant like lignosulfonate),
(b) more complex solids- removal equipment, such as mud cleaners and high-speed centrifuges .

Solids removal on the rig is accomplished by the following techniques: Shale shakers, desander , desilter, centrifuge. Each device is designed to remove a sufficient quantity and size range of solids.Often these are accomplished using separate devices, but sometimes these processes are combined, as in the case of the mud cleaner, which is a bank of hydrocyclones mounted over a vibrating screen. Another important hybrid device is the cuttings dryer (also called a rotating shaker), which is a centrifuge fitted with a cone-shaped shaker; Additional devices can help to enhance solids-removal efficiency. For example, a vacuum degasser is sometimes installed (before any centrifugal pumps, typically between the shakers and desanders) to remove entrained air that can cause pump cavitation and reduction in mud density.

Although,the solids-control equipment used on a rig is designed to remove drilled solids—not all solids—from a drilling fluid, perfect separation of desired from undesired solids is not possible, the advantages offered by the solids-control equipment far outweigh their limitations. Solids removal is one of the most important aspects of mud system control, since it has a direct bearing on drilling efficiency and represents an opportunity to reduce overall drilling costs.The key to efficient solids control is to use the right combination of equipment for a particular situation, arrange the equipment properly, and ensure that it operates correctly.