The primary and probably most important device on the rig for removing drilled solids from the mud.
Because extracting crude oil or natural gas from the ground involves drilling down through several thousand feet of dirt and rock to get to the oil reservoir, it’s tough, grueling work that takes a huge toll on your equipment. One of the most important pieces of equipment in the oil and gas industries is the shale shaker, which is critical because it allows well operators to clean and reuse drilling fluid – or drilling mud – a valuable and expensive resource.
Pumped into the wellbore as it’s being drilled, drilling fluid keeps the drill bit cool and applies hydrostatic pressure that keeps out formation fluids. More important, it carries out the drill cuttings, which is where the shale shaker comes in. The shale shaker separates the cuttings from the drilling fluid by running it through a vibrating screen, allowing the fluid to be pumped back into the well and reused. In addition to saving money, reusing drilling fluid means it doesn’t have to be disposed of, reducing regulatory and compliance costs.
This vibrating sieve is simple in concept, but a bit more complicated to use efficiently. A wire-cloth screen vibrates while the drilling fluid flows on top of it. The liquid phase of the mud and solids smaller than the wire mesh pass through the screen, while larger solids are retained on the screen and eventually fall off the back of the device and are discarded. Obviously, smaller openings in the screen clean more solids from the whole mud, but there is a corresponding decrease in flow rate per unit area of wire cloth.
Drilling crew should seek to run the screens (as the wire cloth is called), as fine as possible, without dumping whole mud off the back of the shaker. Where it was once common for drilling rigs to have only one or two shale shakers.
Modern high-efficiency rigs are often fitted with four or more shakers, thus giving more area of wire cloth to use, and giving the crew the flexibility to run increasingly fine screens.
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