Chapter 16
Kruseman and Ridder (1970)
Stephanie Fulton
March 25, 2014
Background
 Small volume of water—or alternatively a closed cylinder—
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is either added to or removed from the well
Measure the rise and subsequent fall of water level
Determine aquifer transmissivity (T or KD) or hydraulic
conductivity (K)
If T is high (i.e., >250 m2/d), an automatic recording device
is needed
No pumping, no piezometers
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Cheaper and faster than conventional pump tests
But they are NO substitute for pump tests!!!
Only measures T/K in immediate vicinity of well
Can be fairly accurate
Types of Slug Tests
 Curve-Fitting methods (conventional methods)
 Confined, fully penetrating wells: Cooper’s Method
 Unconfined, partially or fully penetrating wells: Bouwer and
Rice
 Oscillation Test (more complex method)
 Air compressor used to lower water level, then released and
oscillating water level measured with automatic recorder
 All methods assume exponential (i.e., instantaneous)
return to equilibrium water level and inertia can be
neglected
 Inertia effects come in to play for slug tests in highly
permeable aquifers or in deep wells
 Prior knowledge of storativity needed
oscillation test
Cooper’s Method (1967)
 Confined aquifer,
unsteady-state flow
 Instantaneous
removal/injection of
volume of water (V) into
well of finite radius (rc)
causes an instantaneous
change of hydraulic
head:
(16.1)
Cooper’s Method (cont.)
 Subsequently, head gradually returns to initial head
 Cooper et al. (1967) solution for the rise/fall in well
head with time for a fully penetrating large-diameter
well in a confined aquifer:
Cooper’s Method (cont.)
 Annex 16.1 lists values for
the function F(α,β) for
different values of α and β
given by Cooper et al.
(1967) and Papadopulos
(1970)
 These values can be
presented as a family of
curves (Figure 16.2)
Cooper’s Method: Assumptions
 Aquifer is confined with an apparently infinite extent
 Homogeneous, isotropic, uniform thickness
 Horizontal piezometric surface
 Well head changes instantaneously at t0 = 0
 Unsteady-state flow
 Rate of flow to/from well = rate at which V changes as head
rises/falls
 Water column inertia and non-linear well losses are negligible
 Fully penetrating well
 Well storage cannot be neglected (finite well diameter)
Remarks
 May be difficult to find a unique match of the data to one of
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the family of curves
If α < 10-5, an error of two orders of magnitude in α will
result in <30% error in T (Papadopulos et al. 1973)
Often rew (i.e., rew = rwe-skin) is not known
Well radius rc influences the duration of the slug test: a
smaller rc shortens the test
Ramey et al. (1975) introduced a similar set of type curves
based on a function F, which has the form of an inversion
integral expressed in terms of 3 independent dimensionless
parameters: KDt/rw2S, rc2/2rw2S and the skin factor
Uffink’s Method
 More complex type of slug test for “oscillation tests”
 Well is sealed with inflatable packer and put under
high pressure using an air line
 Well water forced through well screen back into the
aquifer thereby lowering head in the well (e.g., ~50 cm)
 After a time, pressure is released and well head
response to sudden change is characterized as an
“exponentially damped harmonic oscillation”
 Response is typically measured with an automatic
recorder
Uffink’s Method (cont.)
 This oscillation response is given by Van der Kamp (1976)
and Uffink (1984) as:
Uffink’s Method (cont.)
 Damping constant, γ = ω0B
(16.7)
 Angular frequency of oscillation, ω = ω0 1 − B 2
(16.8)
Where
 ω0 = “damping free” frequency of head oscillation (Time-1)
 B = parameter defined by Eq. 16.13 (dimensionless)
Uffink’s Method (cont.)
Uffink’s Method (cont.)
 The nomogram in Figure 16.4 (below) provides the
relation between B and rc2/ω04KD for different values
of α as calculated by Uffink:
Figure 16.4
Uffink’s Method: Assumptions and
Conditions
 Assumptions are the same as with Cooper’s Method
(Section 16.1), EXCEPT:
 Water column inertia is NOT negligible and
 Head change at t > t0 can be described as an
“exponentially damped cyclic fluctuation”
 Added condition:
 S and skin factor are already known or can be estimated
with fair accuracy
Bouwer-Rice’s Method
 Unconfined aquifer, steady-
state flow
 Methods for full or partially
penetrating wells
 Method is based on Thiem’s
equation for flow into a well
following sudden removal of
slug of water:
 The well head’s subsequent
rate of rise:
Figure 16.5
Bouwer-Rice’s Method
 Combining Eqs. 16.16 and 16.17, integrating, and solving
for K:
Bouwer-Rice’s Method
 Values of Re were experimentally determined using a resistance
network analog for different values of rw, d, b, and D
 Derived two empirical equations relating Re to the geometry
and boundary condition of the system
 Partially penetrating wells:
 A and B are dimensionless parameters which are functions of d/rw
 Fully penetrating wells:
 C is a dimensionless parameter which is a function of d/rw
Bouwer-Rice’s Method
Bouwer-Rice’s Method:
Assumptions and Conditions
Bouwer-Rice’s Method: Remarks