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observations: horizontal permeability is systematically higher than vertical
one. This result is consistent with the observation of many horizontal fractures
in dug wells.
Table 1b:
Permeability and anisotropy degree determined at
observation wells using Neuman method
Observation
r
b
K
r
K
Z
K
D
1/K
D
well
(-)
(m)
(m)
(m/s)
(m/s)
(-)
(-)
IFP-1/1
1.00
28
21.8
8.5E-07
5.2E-07
0.606
1.7
IFP-1/2
0.20
27.5
21.8
8.0E-07
1.0E-07
0.126
8.0
HORIZONTAL FRACTURE INTERSECTING THE PUMPING
WELL USING GRINGARTEN METHOD
Flowmeter vertical profile in IFP-9 (Maréchal et al., 2005) shows that only
one fracture is conductive (at 29 metres depth) and is saturated during the
whole pumping test. Moreover, the analysis by Neuman method arises the
existence of hydraulic anisotropy due to the existence of horizontal fractures
(Marechal et al., 2005). Thus, the method developed by Gringarten and
Ramey (1974) for a vertical well intersecting a single horizontal fracture in
an anisotropic aquifer (Fig. 2), applicable to the pumping well, is well
adapted to the hydrogeological context of IFP-9 well.
Figure 2.
Schematic section of the Gringarten aquifer model
(one single horizontal fracture).
The complexity of the analytical solution necessitates an interpretation
through the adjustment of observed drawdown on theoretical curves (known
as master curves) giving the reduced drawdown in a pumping well as a
function of reduced time for various geometrical configurations represented
by the parameter
H
DG
, when the fracture is located at the centre of the aquifer
z
H
f
0.5
, with
