STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

950 Drilling and Well Completions
3. For the average pressure wave velocity in the pipe, compute the distance
at which the amplitude falls to l/e of its original value, the distance at
which it falls at one-half of its original value (half depth) and the attenuation
in dB/1,000 ft. Compute also the amplitude at surface. Bottomhole
amplitude peak to peak: 200 psi; frequencies: 0.2, 12 and 24 Hz.
Data Sheet. Pressure loss (Equation 4-187) is given by
where dP = pressure loss in psi
dL = pipe or annulus length in ft
y = mud specific weight in lb/gal
vm = mud velocity in ft/s
d = ID pipe diameter in in.
p = mud viscosity in cp
Pressure wave velocity is
where Vw = pressure wave velocity in ft/s
y = mud specific weight in lb/fts
B = fluid bulk modulus in lb/ft2
M = drill pipe modulus in lb/ft2
B = 1/K
where K = mud compressibility in ft2/lb
g, = gravity acceleration 32.2 ft/s2
and
E( Di - Df )
M= 2(1-V)(D;+DP)-(Z*v.Df)
where E = steel Young modulus in lb/ft2
Do = external drill pipe diameter in ft
Di = internal drill pipe diameter in ft
v = steel Poisson ratio
Pressure wave attenuation is
P(x) = P(0) e-vL
where P(x) = wave amplitude at distance x
P(0) = wave amplitude at origin