Page 260 - Well Control for Completions and Interventions

254 Well Control for Completions and Interventions

7.3.8.2 Tubing and annulus volumes
Casing and annulus capacity can be calculated since ID and outer diame-
ter (OD) are known. Alternatively, they could be looked up in tables.

2
Tubing capacity: 4:670 4 1029:4 5 0:0212 bbls=ft:
The reciprocal gives ft:=bbls 1 4 0:0212 5 47:17 ft:=bbls
Tubing volume to SSD: 10; 300 3 0:0212 5 218:36 bbls

2
2
Annulus capacity: ð8:535 5:5 Þ 4 1029:4 5 0:0414 bbls=ft:
The reciprocal gives ft:=bbls 1 4 0:0414 5 24:15 ft:=bbls
Annulus volume to SSD: 10; 300 3 0:0414 5 426:42 bbls
Total volume (tubing and annulus) 5 644.42 bbls.

7.3.8.3 Calculate pressures before and after opening the sliding
side door
• Tubing pressure at the SSD before it is opened has already been
calculated (5500 psi).
• Annulus pressure at the SSD: depth to SSD 3 annulus fluid gradient
10; 300 3 0:52 5 5356 psi:

• Pressure across the SSD can be equalized by applying (5500 2 5356) 5
144 psi to the casing.
• HP at the SSD after the kill will be: 10,300 3 0.5564 5 5731 psi. This
is 231 psi above reservoir/well pressure at the SSD. It is also 31 psi
more than the required 200 psi overbalance. The additional 31 psi is
because the kill fluid density was rounded up from 10.64 to 10.7.
• After opening the SSD, bring the casing pressure up to 375 psi to give
231 psi overbalance at the SSD, 5731 2 5356 5 375 psi.
• As the circulation begins the casing pressure is 375 psi. Pressure at the
SSD (kill depth) is overbalancing well pressure by 231 psi.
• Before the choke is opened the tubing head pressure will read 5731 2
(10,300 3 035) 5 2126 psi.
• The aim is to pump fluid into the annulus whilst maintaining at least a
231 psi overbalance at the SSD by controlling casing pressure on
the choke. As the tubing fills with 0.52 psi/ft. packer fluid from the
annulus, the tubing pressure will fall rapidly.
To complete the kill sheet pump schedule, tubing head pressure and
casing head pressure at each stage of the kill must be calculated. Surface
pressure at each stage of the kill is simply the required pressure at the plug