BAKER HUGHES - Drilling Fluids Reference Manual

FLUIDS ENVIRONMENTAL SERVICES
Diatomite is the fossilized remains of microscopic unicellular plants which lived in ancient water
bodies. It is known for its unique cylindrical geometry; which has high strength, high pore volume
and low resistance to flow, thereby making it an excellent selection for filtration.
The filtration of slurries containing gelatinous, slimy, and/or compressible solids (barite and clay)
typically results in poor filter performance; e.g. low flow rates, short cycle times, high operating
pressures and low filtration efficiency. The addition of non-compressible and highly permeable solids
(diatomaceous earth) to the slurry being filtered can cancel or significantly reduce these undesirable
effects and improve the performance level of the filtration operation.
The addition of diatomaceous earth to the slurry being filtered will alter the physical characteristics of
the formed cake solids by increasing its permeability and reducing the resistan ce to the flow of the
fluid.
Typical dose rates (guideline):
Pre-coating: 1 kg per square meter of filter plate screen.
e.g. 1200 sq meter = 120kg diatomaceous earth.
Body-feed: 1:1 (or more) volume ratio of diatomaceous earth to solids in slurry being filtered.
Highly compressible solids ( barites and clay) typically require higher body-feed addition rates to
affect cake permeability.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 14-59