1. Basic Formulas

Table of Content

  1. Pressure Gradient
  2. Hydrostatic Pressure
  3. Converting Pressure into Mud Weight
  4. Specific Gravity
  5. Equivalent Circulation Density
  6. Maximum Allowable Mud Weight
  7. Pump Output
  8. Annular Velocity
  9. Capacity Formulas
  10. Control Drilling
  11. Buoyancy Factor
  12. Hydrostatic Pressure Decrease POOH
  13. Loss of Overbalance Due to Falling Mud Level
  14. Formation Temperature
  15. Hydraulic Horsepower
  16. Drill Pipe, Drill Collar Calculation
  17. Pump Pressure, Pump Strokes
  18. Cost Per Foot
  19. Temperature Conversion Formulas

1.2 Hydrostatic Pressure (HP)

Hydrostatic pressure, psi, using ppg and feet as the units of measure

HP = mud weight, ppg × 0.052 × true vertical depth (TVD), ft

Example: mud weight = 13.5 ppg, and, true vertical depth = 12,000 ft
HP = 13.5 ppg × 0.052 × 12,000 ft
HP = 8,424 psi

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

HP = psi/ft × true vertical depth (TVD), ft

Example: Pressure gradient = 0.624 psi/ft, and, true vertical depth = 8,500 ft
HP = 0.624 psi/ft × 8,500 ft
HP = 5,304 psi

Hydrostatic pressure, psi, using mud weight, lb/ft3

HP = mud weight, lb/ft3 × 0.006944 × true vertical depth (TVD), ft

Example: mud weight = 90 lb/ft3, and, true vertical depth = 7,500 ft
HP = 90 lb/ft3 × 0.006944 × 7,500 ft
HP = 4,687 psi

Hydrostatic pressure, psi, using meters as unit of depth

HP = mud weight, ppg × 0.052 × true vertical depth (TVD), m × 3.281

Example: mud weight = 12.2 ppg, and, true vertical depth = 3,700 meters
HP = 12.2 ppg × 0.052 × 3,700 m × 3.281
HP = 7,701 psi

⬆ Table of Content