Page 300 - Well Control for Completions and Interventions

Well Kill, Kick Detection, and Well Shut-In 293

6. Without bleeding any fluid, allow SICP to increase by the safety
margin.
7. Without bleeding any fluid, allow SICP to increase by range.
8. Maintaining SICP, bleed small volumes of fluid until the volume in
the tank is equal to that calculated in Step 4.
9. Keep repeating Steps 7 and 8 until gas is at the surface, or until a cir-
culating or bullhead kill can begin (Fig. 7.17).
Small and gradual changes on the choke are recommended. The aim
is to hold a constant casing pressure as fluid is bled from the well. Rapid
opening of the choke, to speed up the process, can easily result in the cas-
ing pressure dropping enough to allow a second influx. It may take several
hours to bring gas to the surface. Patience is required.
Example calculation (Table 7.12):
Procedure (field units):
Volume to bleed (using 100 psi steps) 100 4 11.66 5 8.57 bbls.
1. Allow casing pressure to increase by range (100 psi) above safety
margin (100 psi) above initial SICP: 500 psi 1 100 psi safety margin
1 100 psi range 5 700 psi.

2000
1800
Gas migrating
1600 To surface.

1400 Bleed off whilst holding
Casing pressure (psi) 1200 Range
constant
Casing psi
1000

800
Range
600 Safety margin Initial SICP
400

200

0
0 10 20 30 40 50 60 70 80
Volume bled (bbls)
Figure 7.17 Stair-step schedule for bringing gas to the surface (volumetric method).