STAGE 01 · COARSEST CUT

Shale shaker

The first and cheapest barrel of removal on the rig

The shale shaker is the first line of defence and the single most important machine in the train. A vibrating screen deck throws the whole returning mud stream across mesh that lets fluid through and conveys cuttings off the end. Get the shaker right and every machine downstream has less to do; get it wrong and the whole train spends the section cleaning up what the shaker missed.

What it does

Remove the coarsest drilled solids — cuttings and sand down to roughly 74–100 µm — from the returning mud before any other equipment sees it, while returning clean fluid to the active system.

How it works

A deck of API RP 13C screens is vibrated to impart a controlled motion (linear, balanced-elliptical or circular) at a chosen G-force. Solids are conveyed up the deck and off the discharge end while fluid passes through the openings. The screen sets the cut; the motion and G-force decide how much fluid the deck can handle and how dry the cuttings leave.

Key components

Screen panels (API RP 13C)The working surface — labelled by micron cut point and conductance, not raw mesh. The cut is set here.

Basket / deckHolds the screens at a set angle; its motion is what conveys solids and processes fluid.

Vibrator motorsTwo counter-rotating motors create the straight-line throw on a linear shaker; their condition and phase decide the motion quality.

Feed / possum belly (back tank)Distributes returning mud evenly across the deck width; a mismanaged feed floods one end.

Deck-angle adjustmentSets the beach and pool position; trims the balance between throughput and dry discard.

Screen tensioning / seatingHolds panels flat and sealed — the leading cause of premature tears is incorrect tension or seating.

Operating parameters

Parameter	Range	Notes
G-force	4–8 g	Primary 5–7 g; dedicated drying shakers 8 g+
Motion type	Linear / balanced-elliptical	Linear for capacity; elliptical for dry discard
Screen cut (D100)	section-dependent	Coarser top-hole, finer reservoir
Conductance (kD/mm)	screen-dependent	Higher conductance passes more fluid before flooding

Health indicators — what good looks like

A defined beach — fluid breaking just before the discharge end (healthy).
Cuttings leaving dry, rolling off the end, not over a flooded pool.
Throughput steady at the design rate without flooding.
Sand content low and steady on the suction side.

Common problems & how to fix them

The failures this machine throws, each with a full field fix:

Screen blinding

Near-size particles pack the openings; the pool floods.

Troubleshoot →

Wet cuttings / flooding

Fluid carried over the end — whole mud lost.

Troubleshoot →

Screen failure (holed/torn)

Quiet bypass — looks fine while solids pass through.

Troubleshoot →

Overflowing shaker

Capacity / distribution problem — mud over the back tank.

Troubleshoot →

Solids bypassing the screen

A path around the mesh — gasket, hole, open gate.

Troubleshoot →

Field tips

Read the pool before you change a screen: fluid off the discharge end = flooding (go coarser), a bone-dry deck = you can afford finer.
A flooding deck almost never needs a finer screen — it needs a coarser one and a managed pool.
Replace panels as a set; a fresh screen beside a worn one just unloads onto the old one.
Most premature tears start at the install — tension and seat to the maker's method.

Want this machine read on your rig?

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