document.xls MITCHELL ENGINEERING PROGRAMS

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COPYRIGHT 1990 MITCHELL ENGINEERING, PO BOX 1492. GOLDEN, CO, 80402, USA (303) 273 3744

Aerated Annular PressuresWHILE CIRCULATING AERATED MUD

THE HUGHES TOOL CO. - H B WOODS EQUATION

REF: Bobo, Ormsby, Hoch; "Phillips Tests Air-Mud

Drilling",OIL AND GAS JOURNAL, Feb. 7, 1955, p. 108

SELECTED INPUT VARIABLESSymbols Values Descriptions of Input Variables

-------- -------- -----------------------------------------------------------

Qm 16.957 cu ft of mud circulated/minute; scf/m

Qa 678.261 cu ft of std. air circulated/minute; cf/m

rho air .07642 density of free atmospheric air; lb/cf

rho mud 65.824 density of mud; lb/cf

Dh 8.500 diameter of hole; in

Dp 4.500 OD of drillpipe; in

Po 14.7 pressure at the flow line entry; psia

Temp 60 temperature of atmospheric air; deg F

AV 60 desired annular velocity of mud; ft/m

Air/mud 40 air/mud injection ratio; scf/cf

COMPUTED INTERMEDIATE VARIABLESA .488 '= 0.00708*((C9/C8)*C10+C11)

B 600.300 '= 15*((C9/C8)+0.02)

C .00115 '= 0.00063*C8^2*((C9/C8)*C10+C11)

/((C12-C13)*(C12^2-C13^2)^2)

A+C .48883 '= C18+C20

C*B .69249 '= C20*C19

A*C .00056 '= C18*C20

radian 57.29578 '= 180/PI()

TABLE OF PRESSURE V. DEPTHPressure Depth Gradient 'Depth' at which pressure occurs; ft

15 5 1.15 /($B$21*$B$14^2+2*$B$22*$B$14+$B$22^2)))

100 1491 1.10 -(2*$B$19*SQRT($B$23)/$B$21^2)

200 2482 1.44 *($B$24*ATAN(($B$21*B34+$B$22)

800 5373 2.81 /($B$19*SQRT($B$23)))-$B$24

1,600 7853 3.89 *ATAN(($B$21*$B$14+$B$22)

1,800 8405 4.09 /($B$19*SQRT($B$23)))))

2,000 8943 4.27

2,500 10238 4.67

document.xls MITCHELL ENGINEERING PROGRAMS

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Air Pressure Loss in Rig Piping

Press of Compressed Air 100 psig

Temp of Compressed Air 100 °F

Flow Rate 1500 c.f.m.

Pipe ID 3 in

Length of Pipe 100 ft

Flow Rate of Compressed Air 207.0 c.f.m.

Velocity of Compressed Air 70.3 f.p.s.

Density of Air @ P & T 0.5535 lbs/ft³

Friction Factor 0.0105

Pressure Drop of Compressed Air 1.24 psi/100ft

Compressor Horsepower OutputNumber of Stages 3Compressor Intake Pressure 14.7 psia

Compressor Discharge Pressure 350 psia

Compressor Intake Air Temperature 530 deg R

Metered Air Flow Rate 600 scf/m

Metered Air Temperature 540 deg R

Metered Air Pressure 348 psia

Compressor Horsepower 219 hp

intake

dischargemetercompressor

injection