BAKER HUGHES - Drilling Fluids Reference Manual

RESERVOIR APPLICATION FLUIDS
Drill-in
Fluid
Static
Filter Cake
Cuttings
Bed
Formation
Filter Cake
Figure 6 - 17
Condition of Horizontal Wellbore Prior to Displacement
Once the drill-in fluid has been displaced, the filter cake must be scoured. The figure below
illustrates this process. Critical to the success of hole cleaning is to maximize the fluid velocity
near the wellbore wall. For this reason it is important to fully maintain turbulent flow if possible.
To assist in remaining turbulent, low viscosity fluids are desired for this process. While low
viscosity fluids help to maximize velocity near the wall, it is commonly assumed that their use also
makes it somewhat more difficult to remove solids from the wellbore. To carry solids completely
out of the wellbore, elevated flow velocities are required.
Figure 6 - 18
Scouring of the Filter Cake
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 6-83