Pressure Gradient

Pressure gradient, psi/ft, using mud weight, ppg

• Example: 12.0ppg fluid

• psi/ft = 12.0ppg 0.052

• psi/ft = 0.624

Pressure gradient, psi/ft, using mud weight, lb/ft ³

• Example: 100lb/ft ³ fluid

• psi/ft = 100lb/ft ³ 0.006944

• psi/ft = 0.6944

OR

• Example: 100lb/ft ³ fluid

• psi/ft = 100lb/ft ³ 144

• psi/ft = 0.6944

Pressure gradient, psi/ft, using mud weight, specific gravity (SG)

• Example: 1.0SG fluid

• psi/ft = 1.0SG 0.433

• psi/ft = 0.433

Metric calculations

S.I. units calculations

Convert pressure gradient, psi/ft, to mud weight, ppg

• Example: 0.4992 psi/ft

• ppg = 0.4992 psi/ft 0.052

• ppg = 9.6

Convert pressure gradient, psi/ft, to mud weight, lb/ft ³

• Example: 0.6944 psi/ft

• lb/ft ³ = 0.6944 psi/ft 0.006944

• lb/ft ³ = 100

Convert pressure gradient, psi/ft, to mud weight, SG

• Example: 0.433 psi/ft

• SG = 0.433 psi/ft 0.433

• SG = 1.0

Metric calculations

S.I. units calculations

Hydrostatic Pressure (HP)

Hydrostatic pressure using ppg and feet as the units of measure

• Example: mud weight = 13.5ppg

• true vertical depth = 12,000 ft

• HP = 13.5ppg 0.052 12,000 ft

• HP = 8424 psi

Hydrostatic pressure, psi, using pressure gradient, psi/ft

• Example: pressure gradient = 0.624 psi/ft

• true vertical depth = 8500 ft

• HP = 0.624 psi/ft 8500 ft

• Hp = 5304 psi

Hydrostatic pressure, psi, using mud weight, lb/ft ³

• Example: mud weight = 90lb/ft ³

• true vertical depth = 7500 ft