Formulas and Calculations for Drilling Operations by G. Robello Samuel
Copyright © 2010 Scrivener Publishing LLC.

Appendix: Useful
Conversion Factors
Length
1
1
1
1
1

meter = 39.37 in inch = 2.54 cm feet = 30.48 cm = 0.3048 m mile = 5280 ft = 1720 yard = 1609.344 meter nautical mile = 6076 ft

Mass
1
1
1
1
1
1
1

Ibm = 453.6 g = 0.4536 kg = 7000 gr (grain)
Kg = 1000 g = 2.2046 Ibm slug = 1 lbf s 2 /ft = 32.174 Ibm
US ton = 2000 Ibm (also called short ton) long ton = 2240 Ibm (also called British ton) tonne = 1000 kg (also called metric ton) = 2204.6 Ibm kip = 1000 lb

Force
1 lbf = 4.448 N = 4.448 x 105 dynes
1 lbf = 32.174 poundals = 32.174 Ibm ft/s 2
365

366

FORMULAS AND CALCULATIONS FOR DRILLING OPERATIONS

Gravitational Acceleration g = 32.2 ft/s 2 = 9.81 m / s 2
9.7803267714

2Λ
( l + 0.00193185138639siri λ

2

W l - 0.00669437999013sin X

\

m/s2,

where λ = the geographic latitude of the earth ellipsoid measured from the equator in deg.
Pressure
1 atm = 14.69595 psia = 2118 lbf/ft2
= 29.92 in. Hg = 760 mm = 1.013 bars
= 33.93 ft H 7 0 = 1.013 x 10 Pa = 101.3 kPa l P a = l N / m 2 = lO" 5 bars
Volume
1 ft3 = 7.481 US gal = 6.31 Imperial gal = 28.316 L
1 m3 = 1000 L = 106 cm3 = 264.2 US gal = 35.31 ft = 264.2 gal = 35.31 ft3
1 bbl = 42 US gal = 5.61 ft3
1 bbl = 9694.08 in3
Density
Water = 62.4 lbm/ft 3 = 1000 kg/m 3 = 1 g/cm 3 = 8.33 lbm/US gal
°API, 60° F = (141.5/SG,60°F) -. 131.5
SG, 60° F = (141.5)/(°API,60°F + 131.5)
Velocity
1 knot = 1 nautical mile/hr
60 mph = 88 ft/s

lbxs n ft 2
Temperature
°F = 1.8(°C) + 32
°R = °F+ 459.67 = 1.8 (K)

0.002088543 x e q . c P

APPENDIX: USEFUL CONVERSION FACTORS

Energy
1 J = 1 kg m 2 /s 2 = 107 dyne
1 BTU = 777 ft lbf = 252 cal = 1055 J
1 hp hr = 2545 Btu
1 kW hr = 3412 Btu = 1.341 hp hr
Power
1 hp = 550 ft lbf/s = 33,000 ft lbf/min
Gas Constant
R = 1.987 Btu/lb mol °R = 1.987 cal/g mol K
= 0.7302 atm ft 3 /lb mol °R = 1545 ft lbf/lb mol °R
= 0.08206 L a t m / g mol K
= 82.06 atm cm3 mol K
= 8314 Pa m 3 mol K ox. J/kg mol K
= 8.314kJ/kgm01 K
Viscosity
1 cP = 0.01 Poise = 0.01 g / c m s = 0.01 dyne s/cm
= 0.001 k g / m s = mPa s = 0.001 N s/m 2
= 2.42 lbm/ft hr = 0.0752 slug/ft hr
= 6.72 x 10"4 lbm/ft s
= 2.09 x 1(Γ5 lbf s/ft 2
1 Pa s = 0.0209 lbf s/ft 2 = 0.672 lbm/ft s iv,xsn^ ft2

= 0.002088543 x e q . c P
= 4.79xl04cP

I ft2 J

Acceleration Due to Gravity g = 32.2 ft/s 2 = 9.81 m / s 2
Trigonometric Relationships
CSCÖ + COt Θ -

1 + cos# sin# 367

368

FORMULAS AND CALCULATIONS FOR DRILLING

cscfl + cot0 = cot(0/2) sin0 = 2sin(0/2)cos(0/2) cos0 = cos 2 (0/2) - sin 2 (0/2) sin(fl ±b) = sinacosb ± cos« sinb cos (a±b)= cosa cosb + sinasinb sin0 =

l + e'
1

COS0 =

e' + e

„2/

1—6

„-<

6
T- = —

l + e2'

e'+e'1

sin0 = sechf cos0 = -tanhf cosh2i - sinh 2 i = 1 tanh 2 i + sech2f = 1
/

,

-i

cosh t sinh t =

e'-e~'

sinh 2 0 + cosh20 =