Post on 03-Jun-2018
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HydrogeologicCharacterization
Thomas Doe
Winter 2009
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What You Need to Know from
Previous Lecture Hydrologic Cycle Vadose Zone
Specific Yield Capillary pressure
Groundwater Flow Systems Confined versus Unconfined Flow Perched water Artesian Flow
Hydrologic Units Aquifer, Aquitard, Aquiclude
Properties
Hydraulic Conductivity (K) versus Permeability (k) General ranges for geologic materials Specific capacity (Q/h)
Porous versus Fracture Flow
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Hydrogeologic Characterization
Hydraulic Head and Pressure Hydraulic Gradient
Confined and Unconfined Flow to a Well Definition of Storage and Storativity Difference between De-pressuring and Dewatering
Steady flow and its applications
Theim equation Specific Capacity
Falling Head Test Packer test
Wire line packer
Lugeon Test Flow Log
Transient Flow and its Applications Pump Test Slug Test
Principles of Groundwater Monitoring Piezometer types Piezometer Design
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Pressure and Hydraulic Head
Energy that drives water
Gravity
Chemistry (mainly in clays)
Electricity (mainly in clays)
Pressure is a measure of total energy
Head is a measure of potential energyit iswhat drives flow
Elevation Head
Pressure Head
It is expressed
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Outline
Basic Properties and Parameters
Steady flow to a well
Transient flow to a well Groundwater monitoring
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Flow Velocity
Compare Fracture Velocity to Porous Medium Velocity1-m cubeT=1-e5Fracture Aperture = .0005 mSand porosity = 10%
Gradient = 1
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Steady Flow Methods
Packer Testing
Falling Head Test
Constant Pressure/Lugeon Test
Flow Logging
Heat pulse
Spinner
Hydrophysical
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Useful Definitions and Concepts
Transmissivity -- Properties of a conductor(aquifer, reservoir, single fracture, fracture zone)(L2/T)
Permeability, Hydraulic Conductivity -- Propertyof material inside conductor (L/T)
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Steady Radial Flow
Pressure and flowconstant
Only exists withconstant pressureboundary
Generally under-estimates due to skin
R
rw
h
Q
h
QrRT w
2
)ln(
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Steady Flow Applications
Specific Capacity
Drillers term Flow rate divided by a drawdown
Packer Test
Test usually run with inflatable well sealscommonengineering test
Lugeon Test
Packer test usually for grouting
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Flow Log
Both
Indicate locations of flow features and relativestrengths
Ambient Flow
Indicates up or downward flow due to naturalgradients
Pumped Flow Indicates transmissivity of flowing feature
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Spinner Hydrophysical Log
(1) Replace fluid with deionized water
(2) Log fluid resistivity while pumping
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FLOW RATE AND SINGLE POINT RESISTANCE LOGSDEPTHS OF LEAKY FRACTURESSP, KI0025F03
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6
Flow rate (ml/h)
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
Depth(m)
1E+1 1E+2 1E+3
Single point resistance (ohm)
125.45
124.65
133.3
131.1
128.3
Heat Pulse LogPosiva (Finland) Heat Pulse FlowLog (sp)
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FIGURE E-12
FLOW LOGS FOR BOREHOLES P1-20 AND P1-21MAWS/Campo Landfill Stage 1 WMRP/CA
-250
-200
-150
-100
-50
0-1250 -750 -250 250 750
Depth,ft.
Flowrate, ml/min
Well P1-20
Ambient
Injection
CologAmbient
-250
-200
-150
-100
-50
0
-1250 -1000 -750 -500 -250 0 250 500 750 1000
Depth,
ft.
Flow, ml/min
Well P1-21
Ambient
Injection
Total Dep th: 142 ft
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Image Logging (Correlate Flow to Feature)
Borehole TV (BIPS) FMI (micro-resistivity)
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Wireline Packer
Aardvark/Tigre Tierra
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Packer Test (Fixed Interval Length)
Used in CivilEngineering
Testing at fixed intervallengths
Some zones have nofractures; some zoneshave multiple fractures
Efficient testing hassome no flows but not
too many
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Lugeon Test
Packer Test usually for grouting
1 Lugeon unit = 1 litre of water taken per metreof test length, per minute, at 10 bars pressure(150 psi approx)
Typically done in steps
Implications 1 Lugeon Unitno sweat
10 Lugeon Unitsfire up the grout mixer
>100 Lugeion Unitsfile for a change order
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Stepped Lugeon Test
LinearLaminar Flow
Hydrojacking,Washout
TurbulentFlow
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Hvorslev Falling Head
Fill hole and watchlevel decline
Steady Flow
High Perm (constantpressure) boundary
Variant on SteadyFlow Solution
http://www.aqtesolv.com/
2
1
2
ln 1ln
2
w wr R r hK
b t h
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Transient Testing
Pump Test
Maintain a constant flow and observe transientpressure
Maintain constant pressure and observe transientflow
Slug Test
Look at pressure decay after instant charge of water Interference Tests
Analyze connectivity, storage, diffusivity
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Radial Diffusion Equation(Radial Cylindrical Flow)
1 1r r
r hr
ht
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Exponential Integral (aka Theis equation):
p r t qT
ex
dx qT
rt
x
r t
( , )/( )
4 4 42 4
2
Ei -
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Exponential Integral and Derivative
0.01
0.1
1
10
0 5 10 15 20 25 30 35
logpD
log tD
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Semilog Approximation of the Exponential
Integral
Ei( u u u u u u
) . ln! ! !
........057722 2 3 3 4 4
2 3 4
p r t q
T
t
r( , ) . log
.2 3026
4
22462
(MKS units)
kh=T is inversely proportional to semilog slope
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Semi-log Line (Jacob-Cooper)
Method
Semi-Log Straight Line
0
5
10
15
20
-3 -2 -1 0 1 2 3 4 5 6 7 8 9
Log Time
Pressure
2.3
4
semi-log slope
QT
mm
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Derivative Methods
Plots P/log(t)
Intent to make semi-line unambiguous
Effect is a very powerful tool to interpretgeometry from tests
Derivative is a map of transmissivity versusdistance from the well
Shape of derivative constrains network geometry
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Well Test Function (Exponential Integral) and
(Semilog) Derivative
0.01
0.1
1
10
0 5 10 15 20 25 30 35
logpD
log tD
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Slug Test
http://www.aqtesolv.com/
Transient Flow Infinite Aquifer
Variations forBoundaries
Variations forclosed (water-filled) or open
(open hole with
air waterinterface)systems
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Comments on Interference Tests
Radius of Investigation (very handy !!!)
Estimate diffusivity from response time
Independent of dimension
tr 2
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Interference Demo
Well 2
Well 3
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Groundwater Piezometer Systems
Key Point: Isolate different parts of flow systemWater SamplingPressure monitoring (eg determine flow, seasonal changes, pore pressure)Avoid cross contamination
http://www.claire.co.uk/
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Bure : Westbay System
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Westbay Systems
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Anomalous Osmotic Pressure
(chemically induced)