Page 255 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

424 Reservoir Engineering

At, hours

s Distortion caused by
Q wellbore damage and 1
4000
I- "after production"
I

t P,f = 3534
I
100.000 10.000 1000 loo
(t + &)/At

p,q-

0
Early deviotion caused
by
oL wellbore effects

162.kqppB

Beginning of deviation ot 1' oo
end of transient period 0
I I
o. I I- IO 100
t hours
rltR straight line [13].
such as when wellbore storage distorts most or all of the data, type-curves may
be the only means of interpretation of the pressure data. Typecurves developed
by Ramey et al. [233-2351 and McKinley [236,23'7] for pressure buildup and
constant-rate drawdown tests and by Gringarten [238] for vertically fractured
wells are discussed in a recent monograph [228] Typecurves are used to estimate
formation permeability, damage, and stimulation of the tested well as well as
to identify the portion of the data that should be analyzed by conventional
techniques. Families of type-curves for various conditions are available from the
SPE book order department in Dallas.