50 / 743
Dynamic Data Analysis – v5.12.01 - © KAPPA 1988-2017
Chapte
r 2 – T heory- p50/743
The action here is fairly straightforward, so we will spare you the figures and only show you
the results:
Well radius: If we over-estimate r
w
by 10%, the calculated skin will be over-estimated with
a shift of 0.1. The general rule is that the false skin induced by this incorrect r
w
will be in
the ratio (rw
wrong
/rw
right
). All other parameters will be OK.
Porosity: If we over-estimate
by 10%, k and kh will be OK, there will be a marginal error
on the skin, the reservoir size will be underestimated by 10%, and hence the boundary
distances will be underestimated by 5%.
Compressibility: Same as above. If we over-estimate c
t
by 10%, k and kh will be correct,
there will be a marginal error on the skin, however the reservoir size will be
underestimated by 10%, hence the boundary distances will be underestimated by 5%.
Viscosity: If we over-estimate
by 10%, k and kh will be overestimated by 10%, there will
be no error on skin and the reservoir size will be evaluated correctly.
Thickness: If we over-estimate h by 10%, kh will be correct and k will be underestimated
by 10%. There will be a marginal error in the skin, the reservoir size will be
underestimated by 10%, and hence the boundary distances will be underestimated by 5%.
Rate: If we over-estimate q.B by 10%, C, k.h and k will be overestimated by 10%. The
reservoir size will also be overestimated by 10%, and hence the boundary distances will be
overestimated by 5%. There will also be a minor skin difference.
This is summarized in the table below:
C
Skin
k.h
k
Area Distance
r
w
10%
-
↑ 0.1
-
-
-
-
10%
-
e
-
-
↓ 10% ↓ 5%
c
t
10%
-
e
-
-
↓ 10% ↓ 5%
10%
-
-
↑ 10% ↑ 10% -
-
h 10%
-
e
-
↓ 10% ↓ 10% ↓ 5%
q.B 10%
↑ 10%
e
↑ 10% ↑ 10% ↑ 10% ↑ 5%
Storage & Skin
Permeability
Boundary