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Dynamic Data Analysis – v5.12.01 - © KAPPA 1988-2017
Chapte
r 6 – W ell models -p193/743
The
Standard Skin
considers that we keep the standard vertical well sandface as the flow
area through which the skin factor is applied. This is as if the skin pressure drop was occurring
at the well and not at the fracture sandface.
There are two ways to define the
Fracture Skin
:
hr
A
w
Flow
2
Because the reference areas are the same, under this convention the component skins add up,
and the total equivalent skin
S
T
will be:
M G T
S S S
If one consider
hX A
f
Flow
4
The reference areas are different, under this convention the component skins will need a
normalization to add up, and the total equivalent skin
S
T
will be:
M
f
w
G T
S
X
r
S S
2
Influence of skin
The figure below illustrates the influence of fracture skin on the behavior of the pressure
change and the Bourdet derivative. There is no effect on the derivative but the pressure
change will no longer show the quarter slope behavior of bi-linear flow as the pressure change
become flatter when the fracture skin increases.
Fig. 6.E.9 – Fracture skin influence