BAKER HUGHES - Drilling Fluids Reference Manual

MECHANICAL SOLIDS CONTROL
Fluid (Mud) Cleaners
Figure 10 - 5 Typical cyclone Performance (Comparison by Size)
The hydroclone/screen combination consists of a bank of desilters which are mounted over a fine
mesh vibrating screen (140- to 200-mesh). The desilter underflow is processed by the fine screen.
Particles removed by the screen are discarded and the fluid processed through the screen is returned
to the active system. The effluent or desilter overflow is also returned to the active system. The
fluid cleaner is essentially a fine screen shaker. Its primary purpose is to remove that portion of
sand-sized or larger particles that pass through the rig shaker. Ideally, a 200-mesh screen would be
desirable on the fluid cleaner, however, a 140- to 150-mesh screen is generally necessary to
minimize barite losses.
Fluid cleaners are not recommended on low-weight systems which can utilize a desilter, since the
desilter will remove more solids down in the fine range. On the other hand, on unweighted systems
with very expensive liquid phases, the fluid lost at the desilter underflow may be economically
prohibitive (oil fluids, polymer-KCl fluids, etc.). In these cases, a fluid cleaner may be of assistance
in the control of drilled solids.
The fluid cleaner is not a centrifuge and does not replace a centrifuge on weighted systems.
However, this device does fill a gap if premium shakers are not employed with a weighted drilling
fluid. Rig shakers may only be able to use an 80-mesh screen which removes drilled solids larger
than 178 microns. The centrifuge removes drilled solids smaller than 4- to 6-microns, so it is
apparent that a particle that passes through the 80-mesh screen will be retained in the system until it
is ground down to the 4 to 6 micron range. Utilizing a fluid cleaner with 200-mesh screens would
give a 74-micron cut and fill the gap.
Removal of particles in the 74 to 178 micron range with the fluid cleaner could produce the
following benefits.
BAKER HUGHES DRILLING FLUIDS
REVISION 2006 10-14
REFERENCE MANUAL