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Fracture Trace Analysis of the
Eastern Panhandle, West Virginiah
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Ranson
Inwood
Bunker Hill
Hedgesville
Martinsburg
Charles Town
Gerrardstown
Harpers Ferry
ShepherdstownKurt J. McCoy
USGS-WRDWV District
Charleston WV
Project Objectives
• The USGS Geologic Discipline will conduct detailed lineament analysis based on satellite imagery and aerial photographs.
• USGS WRD Hydrologists will conduct aquifer testing in the field and relate surficial mapping to aquifer properties.
Conventional Fracture Trace Analysis
Fracture traces reflect underlying zones of fracture concentration,weathering, and thus increased permeability. (Indicators: ridge
gaps, soil tonal changes, vegetation, valleys or low areas)
They are useful as a prospecting tool for locating high yieldingwells.
Wells on or adjacent to a fracture trace or fracture trace intersectioncommonly have 10-15 times higher yields.
Fracture Trace Mapping
USGS GD mapping 2003
Previous mappingFrom Hobba, 1976
Well Drawdown Tests
Transmissivity: A measure of the aquifer ability to horizontally transmit water.
Ex. T > 1000 Public Supply WellT < 10 Domestic Well
0.00 - 5.00
5.01 - 50.00
50.01 - 100.00
>100
Well LocationsSpecific Capacity
(gpm/ft)
0.1 1. 10. 100.0.1
1.
10.
100.
T ime (min)
Dra
wdo
wn
(ft)
Boundary Conditions
Imperm
eable
Recharge
Generally one of three responses
expected
(1)
(3)
(2)Ideal
Well Drawdown Tests
1
10
100
1000
10000
100000
0 100 200 300 400 500 600 700 800Depth of well (ft)
Tran
smis
sivi
ty (f
t2/d
)Drawdown TRecovery T
Target wells
Deeper wells generally are located in less transmissive areas indicating fractures are either less dense, have smaller apertures,
or receive little recharge. Depth of zones supplying majority of water to wells is unknown. Generally high production wells are not excessively deep.
0-25 25-50 50-75 >75
Depth to Water (ft bls)
100
101
102
103
104
105
Tra
nsm
issi
vity
(ft2
/d)
n = 37 n = 54 n = 31 n = 9
<150 150-300 >300
Well Depth
100
101
102
103
104
105T
rans
mis
sivi
ty (
ft2/d
)
n = 78 n = 70 n = 49
Cc Ce Obps Obrr Obs Om
Map Unit
100
101
102
103
104
105
Tra
nsm
issi
vity
(ft2
/d)
n = 55
n = 38
n = 2
n = 44 n = 23
n = 25
Syn
clin
e
Ant
iclin
e
Ove
rtur
ned
Ant
iclin
e
Ove
rtur
ned
Syn
clin
e
Plu
ngin
g A
ntic
line
Plu
ngin
g S
yncl
ine
Fold Type100
101
102
103
104
105
Tra
nsm
issi
vity
(ft2
/d)
n = 43
n = 33
n = 14
n = 6
n = 28
n = 11
0-100 100-250 250-500
Distance to Nearest Fracture (m)
100
101
102
103
104
105T
rans
mis
sivi
ty (
ft/2/
d)
n = 33 n = 79 n = 63
0-45 45-90 90-135 135-180
Azimuth of Nearest Fracture (degrees)
100
101
102
103
104
105
Tra
nsm
issi
vity
(ft2
/d)
n = 77 n = 41 n = 69 n = 9
0-250 250-500
Distance to Thrust Fault (m)
100
101
102
103
104
105
Tra
nsm
issi
vity
(ft2
/d)
n = 47n = 33
0-250 250-500
Distance to Cross Fault (m)
100
101
102
103
104
105
Tra
nsm
issi
vity
(ft2
/d)
n = 19 n = 31
Bottom LineDrill Now
Cross faultsComplex folds
Cross strike fracturesBeekmantown Group
Drill Later
DepthDistance from relationships
Thrust faultsTopographic Position
Cross Fault
F
M
Route 45 near Berkeley/
Jefferson County line
0.00 - 5.00
5.01 - 50.00
50.01 - 100.00
>100
Well LocationsSpecific Capacity
(gpm/ft)
F Anticline
I Overturned Anticline
F Plunging Anticline
M Syncline
Fault
0.1 1. 10. 100.0.1
1.
10.
100.
Time (min)
Dra
wdo
wn
(ft)
120103
107
215
275All 15 gpm or more
USGS GD Fracture
Mapping 2003
Rose diagramBased on Length
Direction of bedding
Direction of bedding
Conclusions• While some features appear conducive to exploratory
drilling, high yielding wells can be found in almost any setting.
• Simple fracture trace analysis, while effective, is not enough to fully characterize controls on flow.
• Features/flowpaths may not have a surface expression.
• Data in addition to surficial mapping is necessary. (i.e. surface geophysics, numerical modelling)
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