Page 250 - Well Control for Completions and Interventions

244 Well Control for Completions and Interventions

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a mud weight equivalent (ppg, SG, or kg/m ). ECD includes any increase
over and above HP resulting from fluid friction whilst circulating.
ECD during forward circulation can be calculated as follows.
Oilfield units:

FP ann
ECD ppgÞ 5 1 FDðppgÞ (7.3)
ð
0:052 3 TVD
where:
FP ann : annular friction pressure;
TVD: true vertical depth (ft.);
FD: fluid density in ppg.
SI units:

3
3
ECDðkg=m Þ 5 FP ann 1 FDðkg=m Þ (7.4)
0:00981 3 TVD
where:
FP ann : annular friction pressure;
TVD: true vertical depth (m);
3
FD: fluid density in kg/m .
ECD during reverse circulation is calculated from:
Oilfield units:

FP tbg
ECD ppgÞ 5 1 FDðppgÞ (7.5)
ð
0:052 3 TVD
where:
FP tbg : tubing friction pressure;
TVD: true vertical depth (ft.);
FD: fluid density in ppg.
SI units:

3
3
ECDðkg=m Þ 5 FP tbg 1 FDðkg=m Þ (7.6)
0:00981 3 TVD
where:
FP tbg : tubing friction pressure;
TVD: true vertical depth (m);
3
FD: fluid density in kg/m .
Fluid velocity in the tubing is normally much higher than in the
annulus, as the cross-sectional area is smaller.