Geology Reference
In-Depth Information
derivatives is often masked by well effects) and (iii) flow in fractures and
matrix. The application of Warren and Root method is then justified for this
data set (Fig. 5b). For the interpretation, according to flowmeter measurements
and geological observations,
n
= 3 and
l
= 1 m were used. The hydraulic
conductivity of fracture network
K
f
= 5.3 × 10
-5
m/s and that one of matrix
K
m
= 7.76 × 10
-8
m/s. On Fig. 5b is also presented the interpretation using
Theis method, which cannot properly interpret the drawdown after 470 min
of pumping. This shows the limit of such models for hydraulic tests in hard
rock terrain, and consequently the necessity to use more sophisticated models.
CONNECTIVITY AND FRACTIONAL DIMENSION FLOW
USING BARKER THEORY
In fractured aquifer, flow properties are controlled by the fractures distribution.
Barker model (9) takes account of the dimension of the flow, which results
from the distribution and connectivity of the conductive fractures (Fig. 6).
This theory is a generalisation of the Theis theory considering a radial flow,
n
-dimensional, into a homogeneous, confined and isotropic fractured medium
characterised by a hydraulic conductivity
K
f
and specific storage
S
sf
. This
Generalised Flow Model introduces the fractional dimension of flow,
n
,
which characterises the variation law of flow section according to distance
Figure 6.
The concept of flow dimension (from Black, 1994).
