Page 266 - Well Control for Completions and Interventions

260 Well Control for Completions and Interventions

Pressure at the SSD before bleeding off was 5500 psi. After bleeding
off the tubing head pressure there is a 313 psi pressure differential across
the plug (from below) (5500-5187). If the plug leaked a hydrocarbon
influx would result. This could be prevented by holding back pressure on
the tubing head.

7.3.9.3 Pumping the kill weight fluid
Before pumping begins, the fluid level in the annulus is 2535 ft. below
the surface. It should mean that the volume required to completely fill
the annulus is (0.0414 3 2535) 105 bbls. If the choke were closed this
would be the case. However, with the choke open it is more
complicated.
As kill fluid (0.5564 psi/ft.) begins to fill the annulus, HP initially
begins to increase as the height of the fluid column increases. Increasing
HP in the annulus will cause a U tube effect (Fig. 7.4), forcing annulus
fluid though the SSD and into the tubing. As the pumping continues
three changes happen simultaneously (Fig. 7.4):
• Kill fluid filling the annulus increases HP pushing packer fluid through
the SSD into the tubing.
• The OWC in the tubing (originally at 5357 ft.) moves towards the
surface as oil is displaced from the well.

Oil displaced Kill weight fluid
from tubing filling annulus

2535 ft. 0.56 psi/ft
0.35 psi/ft
0.35 psi/ft
Annulus fluid
level rising in
tubing
0.67 psi/ft
5357 ft.

0.67 psi/ft

5202 psi 5202 psi Annulus pressure
Tubing hydrostatic hydrostatic pressure
pressure increasing increasing initially
then decreases
Figure 7.4 HP change during the well kill.