Drilling mud is employed to regulate subsurface pressures, lubricate the drilling bit, stabilize the well bore, and carry the drill solid cuttings to the surface, among alternative functions. Drill mud is pumped-up from the surface through the hollow drill string, exits through nozzles within the drilling bit, and returns to the surface through the ring-shaped area between the drill string and also the walls of the outlet.
As the drilling bit grinds rocks into drill cuttings, these drill cuttings become entrained within the mud flow and area unitcarried to the surface. so as to come the mud to the recirculating mud system and to create the drill solids easier to handle, the drill solids should be separated from the mud. the primary step in separating the drill cuttings from the mud involves current the mixture of mud and drill solids over vibrating shale shaker screens referred to as sedimentary rock shale shakers.
The liquid mud passes through the screens and is recirculated back to the mud tanks from that mud is withdrawn for pumping downhole. The drill cuttings stay on prime of the sedimentary rock shale shaker screens; the vibrating action of the shale shakers moves the drill solids down the screen and off the tip of the shale shakers to a degree wherever they will be collected and hold on during a tank or pit for more treatment or management.
Often 2 series of sedimentary rock shale shakers area unit used. the primary series (primary shale shakers) use coarse screens to get rid of solely the larger drill solids. The second series (secondary shale shakers) use fine mesh screens to get rid of a lot of smaller particles. In general, the separated drill cuttings area unit coated with an outsized amount ofdrilling fluid roughly equal in volume to the drill cuttings.
Additional mechanical process is commonly employed in the mud pit system to more take away as several fine solids as potential as a result of these particles tend to interfere with drilling performance. This mechanicalinstrumentation typically belongs to at least one of 3 types: 1)
hydrocyclone-type desilters and desanders, 2) mud cleaners (hydrocyclone discharging on a fine screened shaker), and 3) rotary bowl decanting centrifuges. The separated fine drill solids area unit combined with the larger drill cuttings removed by the sedimentary rock shale shakers.
If the drill solids collected by the sedimentary rock shale shakers area unit still coated with such a lot mud that they're unsuitable for consecutive use or disposal step or if the used drilling mud is efficacious enough to gather the maximum amount of it as potential, the drill solids will be more treated with drying shakers utilizing high gravitative separation, vertical or horizontal rotary cuttings dryers, screw-type squeeze presses, or centrifuges. The cuttings dryers recovery extra mud and turn out dry, powdery drill cuttings.
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