INTERNATIONAL WELL CONTROL FORUM Field Units (API) Formula Sheet

June 2000 (Mud/Weight) page 1 of 2

1. PRESSURE GRADIENT [psi/ft] = Mud Weight [ppg] x 0.052

2. MUD WEIGHT [ppg] = Pressure Gradient [psi / ft]

0.052

3. HYDROSTATIC PRESSURE [psi] = Mud Weight [ppg] x 0.052 x True Vertical Depth [ft]

4. FORMATION PRESSURE [psi] = Hydrostatic Pressure In Drill String [psi] + SIDPP [psi]

5. EQUIVALENT MUD WEIGHT [ppg] = 0.052 x [ft] Depth VerticalTrue

[psi] Pressure

6. PUMP OUTPUT [bbl/min] = Pump Output [bbls/stk ] x Pump Speed [spm]

7. ANNULAR VELOCITY [ft/min] = Pump Output [bbls / min]

Annular Volume [bbls / ft]

8. INITIAL CIRCULATING PRESSURE [psi] = SCR or PL [psi] + SIDPP [psi]

9. FINAL CIRCULATING PRESSURE [psi] = [ppg] WeightMud Original

[ppg] WeightMud Kill x [psi] PL or SCR

10. KILL MUD WEIGHT [ppg] = SIDPP [psi]

TVD [ft] x 0.052 + Original Mud Weight [ppg]

11. SHUT IN CASING PRESSURE [psi] = {(Drilling Fluid Grad [psi/ft] - Influx Grad [psi/ft]) x Influx TVD Height [ft]} + SIDPP [psi]

12. EQUIVALENT CIRCULATION WEIGHT [ppg] = Annular Pressure Loss [psi]

TVD [ft] x 0.052 + Original Mud Weight [ppg]

13. HEIGHT OF INFLUX ALONG HOLE [ft] = Kick Size [bbls]

Annular Volume [bbls / ft]

14. GRADIENT OF INFLUX [psi/ft] = (Mud Weight [ppg] x 0.052) - SICP [psi] - SIDPP [psi]

Influx TVD Height [ft]

15. TRIP MARGIN/SAFETY FACTOR [ppg] = Safety Margin [psi]

TVD [ft] x 0.052 + Mud Weight [ppg]

INTERNATIONAL WELL CONTROL FORUM Field Units (API) Formula Sheet

June 2000 (Mud/Weight) page 2 of 2

16. NEW PUMP PRESSURE WITH NEW PUMP STROKES [psi] = Current Pressure [psi] x New SPM

Old SPM

2

(only approximate!)

17. MAX. ALLOWABLE MUD WEIGHT [ppg] = 0.052 x [ft] TVD Shoe

[psi] Pressure off-Leak Surface + Test Mud Weight [ppg]

18. NEW MAASP AFTER KILL [psi] = (Max. Allow. Mud Weight [ppg] - Kill Mud Weight [ppg]) x 0.052 x Shoe TVD [ft]

19. BARYTE TO RAISE MUD WEIGHT [lbs/bbl] = [ppg] WeightMud Kill - 35.8

1500 x [ppg]) WeightMud Original - [ppg] WeightMud (Kill

20. PERCOLATION RATE [ft/hr] = 0.052 x [ppg] WeightMud

[psi/hr] Pressure Pipe Drill in Increase

21. GAS LAWS = P1 V1 = P2 V2 P2 = P1 x V1

V2 V2 =

P1 x V1P2

22. PRESSURE DROP PER FT. TRIPPING DRY PIPE [psi/ft] = [bbls/ft] Displ Metal - [bbls/ft]Capacity Casing

[bbls/ft] Displ Metal x 0.052 x [ppg] WeightMud

23. PRESSURE DROP PER FT. TRIPPING WET PIPE [psi/ft] = [bbls/ft]Capacity Annular

[bbls/ft])Capacity Pipe + [bbls/ft] Displ (Metal x 0.052 x [ppg] WeightMud

24. LEVEL DROP FOR POOH DRILL COLLARS (DRY) [ft] = Length of Drill Collars [ft] x Metal Displ [bbls / ft]

Casing Capacity [bbls / ft]

25. PIPE TO PULL BEFORE WELL STARTS TO FLOW [ft] = [bbls/ft] Displ Metal x 0.052 x [ppg] WeightMud

[bbls/ft]) Displ Metal - [bbls/ft]Capacity (Casing x [psi] eOverbalanc

26. VOLUME TO BLEED TO MAINTAIN BHP [bbls] = [psi] Pressure in Increase - [psi] Pressure Formation

[bbls] VolumeKick Original x [psi] Pressure in Increase