Page 301 - Well Control for Completions and Interventions

294 Well Control for Completions and Interventions

Table 7.12 Data for volumetric bleed calculation
Data Field units SI units

Fluid in annulus 12 ppg 1437.91 kg/m 3
3
1
5
9/8 in. 47 lb/ft. 3 4/2 in. annular 0.0535 bbls/ft. 0.0279 m /m
3
capacity (18.69 ft./bbl) (38.81 m/m )
P h per bbl or m 3 11.66 psi (18.69 ft.) 504 kPa/m 3
Initial SICP following influx 500 psi 3448 kPa
2. Bleed pre-determined volume (8.5 bbls). Reduction in fluid hydro-
static means casing pressure will be 700 psi 1 100 psi margin 5
800 psi.
3. Allow casing pressure to build by 100 psi (range) 800 1
100 psi 5 900 psi.
4. Bleed pre-determined volume (8.5 bbls). Reduction in fluid hydrostatic
means casing pressure will be 900 psi 1 100 psi margin 51000 psi.
5. Keep repeating until gas is at the surface.
Procedure (SI units):
3
Volume to bleed (using 700 kPa steps) 700 4 504 5 1.38 m .
1. Allow casing pressure to increase by range (700 kPa) above safety
margin (700 kPa) above initial SICP (3448 kPa): 3448 1 700 kPa
safety margin 1 700 kPa range 5 4848 kPa.
3
2. Bleed pre-determined volume (1.38 m ). Reduction in fluid hydrostatic
means casing pressure will be 4848 1 700 kPa margin 55548 kPa.
3. Allow casing pressure to build by kPa (range) 5548 1
700 kPa 5 6248 kPa.
3
4. Bleed pre-determined volume (1.38 m ). Reduction in fluid hydrostatic
means casing pressure will be 6248 1 700 kPa margin 56948 kPa.
5. Keep repeating until gas is at the surface.

7.7 LUBRICATE-AND-BLEED

The lubricate-and-bleed procedure is used to kill gas wells, or
liquid producing wells with a large gas cap, where circulation is not possi-
ble. Gas in the wellbore is replaced with kill fluid whilst keeping bottom
hole pressure constant at above reservoir pressure, to prevent an additional
influx from the formation. Lubricate-and-bleed is also used on wells
where sustained annulus pressure is a problem, i.e., wells where casing