Page 276 - Well Control for Completions and Interventions

Well Kill, Kick Detection, and Well Shut-In 269

• Oil gradient 0.35 psi/ft. 3 7425 ft. 5 2598.75 psi-2599 psi.
• 2599 psi (oil hydrostatic) 1 2967 psi (gas hydrostatic) 5 5566 psi.
• Tubing pressure at the SSD 5566 psi 1 200 psi overbalance 5 5766 psi.
• 5766 psi/10,925 ft. TVD 5 0.528 psi/ft.-0.53 psi/ft. (10.2 ppg).

7.3.10.4 Calculate pressure differential at the sliding side door before
and after opening
• Annulus pressure at the SSD:
• 10,925 3 0.433 5 4731 psi.
• Tubing pressure at the SSD has already been calculated (5566 psi).
• Pressure differential is 5566 2 4731 5 835 psi from tubing to annulus.
Pressure differential can be equalized by applying 835 psi to the casing.
• Pressure at the SSD after the kill will be: 10,925 ft. 3 0.53 psi/
ft. 5 5790 psi. This is 224 psi above well pressure at the SSD, 24 psi
more than the required 200 psi overbalance.
• The additional 24 psi is because of rounding up the brine fluid
gradient.
• After opening the SSD, 1059 psi pressure needs to be applied to the
casing to hold the required 200 psi overbalance.
• 5790 psi (HP at the end of the kill) 2 4731 psi (casing HP at the
SSD) 5 1059 psi.
• At the start of pumping, the pressure either side of the SSD is
5790 psi, as 1059 psi has been applied to the casing. Backing out the
HP in the tubing, wellhead pressure would in theory read:
• 7425 ft. oil at 0.35 psi ft. 5 2599 psi.
• The HP of 3500 ft. of 0.65 sg gas is 0.082 3 3500 5 287 psi.
• 5790 2 2599 2 287 5 2904 psi.

7.3.10.5 Calculate tubing and annulus capacities
2
1
• 5/2 in. tubing: 4.892 /1029.4 5 0.0232 bbls/ft.
2
1
• 4/2 in. tubing: 3.958 /1029.4 5 0.0152 bbls/ft.
2
2
3
1
• 10/4 in. casing3 5/2 in. tubing: (9.560 5.5 )/1029.4 5 0.0593 bbls/ft.
2
2
1
• 9/8 in. casing 3 5/2 in. tubing: (8.535 -5.5 )/1029.4 5 0.0414 bbls/ft.
5
2
2
5
1
• 9/8 in. casing 3 4/2 in. tubing: (8.535 -4.5 )/1029.4 5 0.051 bbls/ft.
(Table 7.9).
To enable tubing head pressure to be plotted against fluid pumped, it
will be necessary to calculate tubing head pressure and casing pressure at
several stages throughout the kill. These must include any point at which