BAKER HUGHES - Drilling Fluids Reference Manual

PRESSURE PREDICTION AND CONTROL
Other names for RCP are,
• Slow Circulating Pressure
• Kill Rate Pressure
• Pre-Recorded Circulating Pressure.
Figure 12 - 12 “U” Tube Circulating
This pump pressure should be obtained by circulating at a predetermined circulation rate. The
corresponding pressure on the standpipe gauge is the RCP. This pressure should be recorded
each hour or when significant fluid property changes are made. Higher fluid weights require
higher pressures for any given circulation rate. The increase can be determined by a simple
ratio,
where,
P 1 = old circulating pressure
P 2 = new circulating pressure
MW l = old fluid weight,
MW 2 = new fluid weight.
⎛ MW
P
2
= P
⎜
1
⎝ MW
2
1
⎟ ⎞
⎠
Note:
If pressure is held on the annulus, this pressure adds to the standpipe,
and is also felt at the bottom of the hole.
When bottomhole pressure becomes less than formation pressure, formation fluids can intrude
into the wellbore as shown in Figure 12-13.
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 12-27