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

1.7 Pump Output (PO)

Triplex Pump - Formula 1

PO, bbl/stk = 0.000243 × (liner diameter, in.)2 × (stroke length, in.)

Example: Determine the pump output, bbl/stk, at 100% efficiency for a 7-in, by 12-in, triplex pump:
PO @ 100% = 0.000243 × 72 × 12
PO @ 100% = 0.142884 bbl/stk

Adjust the pump output for 95% efficiency: Decimal equivalent = 95 ÷ 100 = 0.95
PO @ 95% = 0.142884 bbl/stk × 0.95
PO @ 95% = 0.13574 bbl/stk

Triplex Pump - Formula 2

PO, gpm = [3 (D2 × 0.7854) S] × 0.00411 × SPM

where D = liner diameter, in. S = stroke length, in. SPM = strokes per minute

Example: Determine the pump output, gpm, for a 7-in, by 12-in, triplex pump at 80 strokes per minute:
PO, gpm = [3 (72 × 0.7854) 12] × 0.00411 × 80
PO, gpm = 1385.4456 × 0.00411 × 80
PO = 455.5 gpm

Duplex Pump - Formula 1

Pump output @ 100% eff =
0.000324 × (Liner Diameter, in.)2 × (stroke length, in.)
− 0.000162 × (Liner Diameter, in.)2 × (stroke length, in.)

Example: Determine the output, bbl/stk, of a 5-1/2 in, by 14-in, duplex pump at 100% efficiency. Rod diameter = 2.0 in. :
PO @ 100% eff = 0.000324 × 5.52 × 14 − 0.000162 × 2.02 × 14
PO @ 100% eff = 0.128142 bbl/stk

Adjust pump output for 85% efficiency: Decimal equivalent = 85 ÷ 100 = 0.85
PO @ 85% = 0.128142 bbl/stk × 0.85
PO @ 85% = 0.10892 bbl/stk

Duplex Pump - Formula 2

PO, bbl/stk = 0.000162 × S × [2×D2 − d2]

where D = liner diameter, in. S = stroke length, in. SPM = strokes per minute

Example: Determine the output, bbl/stk, of a 5-1/2-in, by 14-in, duplex pump 100% efficiency. Rod diameter — 2.0 in. :
PO @ 100% = 0.000162 × 14 × [2 (5.5)2 − 22 ]
PO @ 100% = 0.000162 × 14 × 56.5
PO @ 100% = 0.128142 bbl/stk

Adjust pump output for 85% efficiency:
PO @ 85% = 0.128142 bbl/stk × 0.85
PO @ 85% = 0.10892 bbl/stk

⬆ Table of Content