BAKER HUGHES - Drilling Fluids Reference Manual

PRESSURE PREDICTION AND CONTROL
capable tool if the correct input data is used. For water based drilling fluids, as they are not so
strongly influenced by temperature and pressure the normal Fann 35 data should be sufficient.
The practice of using PV / YP for hydraulics calculations should be avoided.
The total pump pressure when circulating is the friction required to move the fluid through the
drilling system. The bit nozzles can take 50% to 60% of the pressure drop with most of the rest
being lost in the drillpipe. These pressures do not affect bottom-hole pressure because the
pressure losses occur before the fluid enters the annulus.
The pressures in the circulating system, shown in Figure 12-10, can be divided as follows.
Surface system (2)
Drillpipe (3)
Drill collars (4)
Bit jets (5)
Annulus flow (6)
Pump pressur e (standpipe gauge)
(1) = The sum of the above
The annulus flow (6) puts pressure on the open hole. This is the annular pressure element in the
ECD.
BHP = Hydrostatic pressure + Annular friction loss
Figure 12 - 10 System Pressure Losses
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 12-25