BAKER HUGHES - Drilling Fluids Reference Manual

MECHANICAL SOLIDS CONTROL
3. Calculate the volume of drilled solids, Vm:
Vw
Vm =
kw
4. Calculate the volume of drilled solids, Vc:
2
Vc = 0.000971×
D × L×W
5. Calculate the dilution volume required if no solids were removed Vd:
Vd
Vc
=
ks
6. Calculate the dilution factor, DF:
DF = Vm
Vd
7. Calculate the total solids removal performance, Et:
Et = ( 1−
DF )
Multiply the result by 100 to calculate a percentage
The accuracy of the API procedure depends somewhat on a relatively constant solids concentration
in the mud, constant surface circulating volume, and consistent averaging techniques over the
interval of interest. The total solids removal performance by this method should be reported at
frequent intervals during the course of drilling the well..
EFFECTS OF SOLIDS ON RHEOLOGICAL PROPERTIES
A brief review of the effects of drilled solids on the flow properties of water-base drilling fluids is
necessary to assist in determining the effectiveness and need of solids control.
Plastic viscosity is largely due to mechanical friction between solid particles in the drilling fluid,
and to a lesser degree the friction between solid and liquid. The plastic viscosity value depends
primarily on the size, shape and concentration of solids in the system, and the viscosity of the
liquid phase. Day-to-day trends in plastic viscosity can give an indication of an increasing degree
of fineness within the solids concentration and can be utilized as a guide in determining the
necessity for centrifuging and dilution.
Yield point and gel strength indicate the degree of attractive forces existing between particles in the
system. Chemical treatment is usually indicated when high yield and gel values are present.
Dilution or mechanical removal of solids may also reduce yield and/or gels. These attractive forces
are related to the distance between the particles. Either of these actions will result in increased
particle separation.
BAKER HUGHES DRILLING FLUIDS
REVISION 2006 10-5
REFERENCE MANUAL