The small pumps mentioned in this discussion can be used for mud mixing in a simple jet hopper mud mixer that can be constructed from standard pipe fittings. One such design follows.
Propeller-type mixers (Mud Agitators)
Simple propeller mixers may be driven by vertical spindle petrol engines (e.g. lawnmower motors) or by hydraulic or electric motors, which require much less maintenance.
A typical propeller-type mixer is illustrated in Figure 2.
Hootonanny or polymer eductors
The above device is used to suck the polymer from a container with a hose that is attached to the top. A water hose from a pump is attached to the side of the device. The mud mix is discharged from the bottom of the device.
A typical device has a water inlet of ¾”, a 1” suction hose, and requires a water flow of 76 Lpm (20 gpm) at a minimum pressure of 1.4 bar (20 psi).
As depicted in Figure 4, in a hydrocyclone the mud feed enters the chamber tangentially, causing the fluid to spin at high speed. This rotation separates the heavier solids from the lighter liquids.
An overloaded hydrocyclone will discharge cuttings in a stream, and these cuttings look like a rope or a string of sausages. When operating correctly, solids spray from the underflow opening, and air is sucked up through the centre of the spray.
Cyclones are best operated continuously with a steady pressure, such as from a centrifugal pump. They can be driven by the rig circulation pump, turning the flow to the cyclone whenever it is not being used to circulate the hole.
Procedure for operating a mud hopper and hydrocyclone
The mixing hopper is described above. To operate the hopper, the pump pressure should exceed 700 kPa (100 psi).
Mud flowing to the desander should be at a pressure between 150 and 300 kPa (20–40 psi).
If the pressure is too low, whole mud will flow through the underflow opening.
If the pressure is too high, the underflow opening will choke up.
Mud Cleaners System
Mud cleaning systems use a combination of hydrocyclones and vibrating screens. They come in different sizes depending on the quantity of mud that is to be cleaned. They can be trailer mounted, truck mounted, skid mounted, or supplied as large fixed systems.