t e c h n ol o gi e s of TEM in C h ina G u o qi a ng X ue W ei y ing C hen D o n g ya ng H o u I n s t itute o f G e o l o ID: 485265
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Slide1
New technologies of TEM in China
Guoqiang Xue, Weiying Chen, Dongyang Hou
Institute of Geology and Geophysics, Chinese Academy of Sciences
J
o
ur
n
al
of
G
e
o
p
h
y
sics
&
R
e
mo
t
e
S
e
n
s
i
ngSlide2
OUTLINES1. Introduction
2. new technology1-Infinitesimal point charge3.
new technology2-Electric source short-offset TEM4. new technology3-Modi
f
ied
cen
t
ral
l
oo
p
T
E
M
5
.
n
ew
tec
hno
l
og
y
4
-
EM
p
se
u
d
o
-
sei
s
m
ic
i
m
a
g
i
n
g
6
.
Re
f
erenceSlide3
1. Introduction
T
r
a
ns
ie
n
t ele
c
tr
o
m
a
g
n
etic
m
et
h
o
d
（
T
EM）is a time domain method in electromagnetic exploration, which is sensitive to conductive targets and have been widely used in mineral source, coal, ground water, environment and engineering investigation(Nabighian,1991).
1
.1
TEM
I
nt
r
o
ducti
o
nSlide4
1. Introduction continued1.2 Some vit
al issues in TEM explorationUnderstan
d and calculate the TEM response base on its physical mechanism
.
G
rea
t
er
i
nv
e
st
i
g
a
ti
o
n
d
e
p
th
is needed to meet the need from deep mineral deposits and coal hydrogeology.Higher precision and faster detection for both shallow and deep investigation.Efficient processing method suitable to 2D and3D data.Slide5
2. Infinitesimal Point Charge2.1 Tr
aditional approach to calculate TEM responsedue to a f
inite source1). Regard the source as a dipole(Kaufman,1987) 2). Regard
t
h
e
s
ou
rce
as
a
s
up
er
p
o
s
i
ti
o
n
of manydipoles(Nabighian,1991)The relative error drops with the decrease of dipole dimension. The smallest and intrinsic source should be point chargeSlide6
2. Infinitesimal Point Charge continued
t xx 2
1 J x, x, Te4t
d
x
d
0 D 2.2 BasisAccording to Maxwell equations so long as an electric charge varies with time it willexcite electromagnetic wave .2.3 MathematicsBased on poi
n
t
c
h
a
r
g
e
h
y
po
t
h
esi
s
,
T
EM
f
ield
a
n
al
y
tical
s
o
l
u
ti
o
n
h
as
b
e
e
n
d
e
r
i
v
ed
b
y i
n
tr
o
d
u
ci
n
g
ti
m
e
-
do
m
ain
G
r
een
f
un
cti
o
n
.
I
n
te
g
r
al
f
or
m
u
la
h
as
b
een
us
ed
to tra
ns
f
o
r
m
ele
c
tr
o
m
a
g
n
etic
f
ield
d
a
m
p
i
n
g
w
a
v
e
e
q
u
ati
o
n
i
n
to
G
r
e
e
n
f
un
cti
o
n
i
n
te
g
r
al
f
o
r
m
.
A
ux
iliary
p
ath
h
as
b
e
e
n
c
o
n
s
tr
u
cted
f
o
r
s
o
l
v
i
n
g
s
i
ngu
la
r
ity
p
r
ob
le
m
.
F
o
u
r
h
ea
v
y
g
e
n
e
r
alized
i
n
te
g
r
al
f
or
m
u
la
o
f
ti
m
e
-
do
m
ain
elect
ro
m
a
g
n
etic
f
ield
r
esp
o
n
s
e
h
as
b
e
e
n
a
r
r
i
v
ed
b
y
u
s
i
n
g
J
o
r
d
a
n
'
s le
mm
a,
t
h
e
r
esid
u
e
t
h
e
o
r
em
a
n
d
g
e
n
e
r
aliz
e
d
f
un
cti
o
n
m
et
h
od
.
Dir
e
c
t
-
ti
m
e
-
do
m
ain
e
x
act
s
o
l
u
tion
o
f
D
’
A
le
m
b
e
r
t
e
q
u
ati
o
n
s
f
irst
l
y
h
as
b
e
e
n
d
e
r
i
v
e
d
(
Z
h
o
u
,
2013
;X
u
e
,
2014
)
.
E
(
x
,
t
)
Slide7
2.4 Comparison with dip
ole2. Infinitesimal Point Charge continuedSolid line repr
esents infinitesimal point charge (left figure) and measur
e
d
d
a
ta
(
r
i
g
h
t
fi
g
u
r
e
),
dashed represents dipole (both figures)It is shown that the field of the infinitesimal point charge in the near source zone is different from that of dipole, whereas the far-source zone fields of these two sources are identical. The comparison of real and simulated data shows that the infinitesimal point charge represents the real source
b
e
tt
e
r
th
a
n dipo
l
e
sour
c
e
.Slide8
3. Electric Source Short-offset TEM3.1 Bac
kgroundLoop source excites o
nly horizontal induction current, while grounded wire source has both ho
r
iz
o
n
tal
a
n
d
v
e
r
tical
i
n
d
u
cti
o
n current. This leads to loop source TEM only sensitive to conductive targets.Detection depth of loop source TEM usually is shallower than 1km.Difficult to lay the transmitting loop at mountain areas.Slide9
3. Electric Source Short-offset TEM continued3
.1 Background ContinuedLOTEM(Str
ack,1992)Advantage: great detectiondepth (more than10km)
Di
s
a
dv
a
nt
a
g
e
s
:
g
r
eat
s
o
u
r
c
e- receiver distance (2~20Km), weak signal, volume effect, poor precision,MTEM(Ziolkowski,2007)Advantage: great power, pseudorandom transmitting source; multi-channel array, multi component, 3D detection; Pse
u
d
o
-
s
eis
m
ic
i
m
a
g
i
n
g
o
f
d
ata
Di
s
a
dv
a
nt
a
g
e
:
h
ea
v
y
,
h
a
r
d
to
c
o
nduct at mountain area; mainly used in marine; systemic and robust equipment have not been introduce to chinaSlide10
3. Electric Source Short-offset TEM continued3
.2 DefinitionShort-offset TEM (abbreviate
d to SOTEM) means that the distance between transmitter and receiver is
a
pp
r
ox
i
m
a
t
e
l
y
e
q
u
al
t
o
o
r le
ss than the exploration depth(Xue,2013).Typical SOTEM layout diagramSlide11
3. Electric Source Short-offset TEM continued3
.3 Observation area for each EM component
5
3
9
0
o
x
y
3
5
9
0
o
6
0
o
6
0
o
y
4
4
4
7
0
o
7
0
o
7
0
o
7
0
o
4
x
x
y
5
16
0
o
16
0
o
5
4
4
4
x
4
7
0
o
7
0
o
7
0
o
7
0
o
x
5
5
3
90
o
6
0
o
9
0
o
3
6
0
o
x
y
3
3
16
0
o
E
y
x
16
0
o
E
y
y
Ez
Hx
Hy
HzSlide12
3.4 All-time apparent resistivity
1E-005
0.0001
0.001
0.01
0.1
1
1E-005
0.0001
0.001
0.01
0.1
1
10
100
1000
10000
100000
t
y
p
e
H
a
ll
ti
me
e
a
r
ly
t
ime l
a
te
t
ime
t
(
s)
r
1
=
1
00
W
.
m
h
1
=
5
00
m
r
2
=
1
0
W
.
m
h
2
=
5
00m
r
3
=
1
0
0
W
.
m
3
.
E
l
e
c
t
r
i
c
So
u
rce
S
h
or
t
-
o
f
f
set
TE
M
cont
i
n
u
ed
0
.
000
1
0
.
00
1
0
.
0
1
0
.1
1
10
100
1000
p
2
50
25
10
5
C
a
lcul
at
ed
by
p
o
l
y
n
o
m
i
a
l
f
it
t
ing
m
e
t
h
o
d
C
a
lcul
at
ed
by
dicho
t
o
m
y
m
e
t
h
o
dSlide13
3. Electric Source Short-offset TEM continued3
.5 ImagingElectric field underneath the T
x
2
x
u
E
(
z
,t
)
=
I
l
ρ
[
e
rf
(
)
-
1 +( 2u- 1 )(1+ u2)e-u /2 ]πz32 π 2 22Time of maximum of Ex for a given depthz=zimag
e
d
E
x
(
z
,
t)
=0
dt
I
m
ag
e
depth
i
mag
e
z
2
(
t)
=
4t
μ
0
σ
Hz
f
r
o
m
a
cur
r
ent
f
il
a
m
ent
l
ocated at image depthzH
I
y x
L
x
L
4
y
2
z
2
(
(
x
1
)
2
y
2
z
2
)
1
/
2
(
(
x
1
)
2
y
2
z
2
)
1
/
2
s
l
o
w
ne
s
s
0
d
t
=
1
z
μ
σ
d
z
2
C
o
n
d
uc
t
i
v
ity of
the
image
0
2
d
2
t
d
z2
Sour
ce im
age fo
r a
three
-lay
er modelSlide14
3. Electric Source Short-offset TEM continued
3.6 Case studyInvestigation o
f hydrous coal mine in Shandong Province
Di
s
c
o
v
e
r
y
o
f
Da
w
a
n
g
z
h
u
a
ng Iron Ore in Anhui ProvinceSlide15
4. Modified Central Loop TEMRegular ce
ntral loopTEM has only one survey point
at once layout, which leads to energy waste and low work efficiency4
.1
R
e
a
s
o
ns
T
he
v
er
t
ic
a
l
m
ag
netic
response in the centralpart of loop is Approximately equal (Xue,2012)The modified deviceutilize the signal from a bigger central part which about 1/3 of loop area.Slide16
4. Modified Central Loop TEM continued4.2 Modified theo
ry1zI0
k2a3H () [3 (3 3k a k2a2 )ek1a ]
1 1
3
2
a
t
5
t
B
z
(
t
)
4
t
2I a2 L (t) 0 ( 0 0 )2 2 0 0 1 2 1 3 12 31zIk ak1a H () [Z (r) (Z (r)
Z
(
r
)
k
a
Z
(
r
)
k
a
)
e
]
0 1
0 0
2
3
L
z
a
6
0
t
u Z
(
r
)
I
(B (t)) [ tB(t)
]
t
t
C
e
n
tr
al
loop
M
o
d
i
f
ied
C
e
n
t
r
al
loopSlide17
4. Modified Central Loop TEM continued4.3 Modified instru
ments
Air coil:heavyand with smallreceivearea(100m2
)
M
ag
ne
t
ic
p
r
o
be: p
o
r
ta
ble
a
nd
w
ith
great receive area(10000m2, 20000m2)Probe 1coilProbe 2
0
.
01
0.
1
10
1
t
/
ms
10000
1000
100
10
1
0
.
1
0
.
01
S
i
g
n
i
f
ic
a
ntly
inc
r
e
a
s
e
t
he
s
i
g
n
a
l st
r
en
gthSlide18
5. TEM Pseudo-seismic Imaging
5.1 B
asic theory(Xue,2013)Background1). The precision in
T
EM
p
r
o
s
p
e
c
ti
n
g
is
r
elati
v
e
low compare with seismic method 2). Interpretation and judgment always be made based on experience of interpreter 3). 2D and 3D TEM inversion are time-consuming and expensive.For the aim to improve th
e
p
r
e
c
i
s
i
o
n
,
c
a
n
w
e
i
n
te
r
p
r
et
T
EM
d
ata
s
i
m
ilar
to
s
eis
m
ic
m
et
h
od
?Basic equation constructionDiffusion equations for TEM2 2 U(r, )
(
r
)
U
(
r
,
)
0
0
1
2
t
3
2
H
m
(
t
)
e
4
t
U
(
)
d
H
(
r
,
p
2
)
U
(
r
,
p
)
H
m
(
r
,
t
)
(
r
)
t
H
m
(
r
,
t
)
0
Di
f
f
u
s
i
o
n
e
q
u
ati
o
n
s
for s
eismic
Inv
erse
Laplace
trans
form
1
2
2
1
1
3
n
2
j
i
4
t
i
4
t
i
t
i
n
1
j
2
q
q
q
H
2 1 1
j
( n
n1
)Um
)
j 1
j 1
)U j
ne
(
(
)U
2
e
( e
2
t
Di
s
c
r
eteSlide19
5. TEM Pseudo-seismic Imaging continued
5
.2 Key techniquesWavelet extractionKirchhoff
in
t
e
g
r
al
f
u
n
c
t
ion
1
u(x, y, z,t) [u] (1) 1[ u ] 1 r [ u ]dQ F4 Q n r r n vr n t r0----main idea o
f
ca
l
c
u
l
a
t
i
o
n
1
)
.
n
o
r
m
a
l
i
z
e
m
e
t
h
o
d
h
a
s
b
ee
n
a
d
o
p
t
e
d,
2). optimizing normalizing parameter havebeen selected by deviation theory 3).Newton iterative f
o
r
m
t
o
b
e
u
s
e
d
t
o
m
a
ke
t
h
e
t
r
a
n
s
f
o
r
m
e
d
w
a
v
e
f
i
e
l
d
s
t
a
b
l
e
a
n
d
r
e
li
a
b
l
e
.
M
i
g
r
a
t
i
o
n
i
m
ag
i
n
gSlide20
5. TEM Pseudo-seismic Imaging continued5.3 Model
s simulation1
5 m,h1 80m2 500 m1
1
m
,
h
1
6
0
m
2
10 m, h2 60m3 100 m1 10 m2 300 mh 70mSlide21
5. TEM Pseudo-seismic Imaging continued5.4 Cas
e studyRecognizing electrical
interfacein Shanxi provinceDetecting deep electric
s
t
ruc
t
u
r
e
a
nd d
is
t
rib
u
t
i
o
n in
G
uan
gdong provinceSlide22
6. ReferenceG.Q. Xue, Geliu
s, L.Xiu 3-D Pseudo-seismic Imaging
of TEM data– a Feasibility Study. GeophysicalProspecting, 2013, 61
(
S
1
)
,
:
561–
5
7
1
d
o
i
:
1
0
.
111
1
/j.1365-2478.2012 . 01109.Guo-Qiang X, Wei-Ying C, Nan-Nan Z, Hai L, Hua-Sen Z (2013) Understanding of Grounded-Wire TEM Sounding with Near-Source Configuration. J Geophys Remote Sensing 2:113. doi: 10.4172/
21
6
9
0049
.
10
0
0
1
1
3
K
a
u
f
ma
n
,
A
.
A
.,
a
n
d
K
elle
r
,
G
.
V
.,
1983
,
F
r
e
qu
e
n
cy
and transient sounding: Methods in geochemistry andgeophysics: Elsevier Publ. Co, 1–32.Nabighian, M.
N
.,
a
n
d
M
ac
n
a
e
,
J.
C
.,
1991
,
T
i
m
e
-
d
o
ma
in
ele
c
t
ro
ma
g
n
e
ti
c
p
ro
s
p
e
c
ting
m
e
th
o
d
s:
in
N
a
bi
g
hi
a
n
,
M
.
N
.
(
e
d
.
)
,
E
l
e
c
t
r
o
ma
g
n
e
ti
c
m
e
th
o
d
s
i
n
a
pplied
geoph
ysic
s–Theo
ry volu
me II,
Part
A, S
ocie
ty of
Exp
loratio
Geoph
ysici
sts, T
ulsa,
Strack
K M.E
xplor
ation
with dee
p tr
ansien
t elect
romagn
etic m
ethod[M],
Els
evier
,1992
Xue
, G.Q
., Bai,
C.Y
., and
Yan,
Y.,
2012, D
eep so
unding T
EM inve
stigati
on m
ethod
based
on a
modif
ied f
ixed
centr
al-loop
syst
em: Jo
urnal
of A
pplied
Geo
physics,
76(2012
) 23–32.
Xue
, G.Q
., Wan
g, H
.Y., Y
an S., Z
hou
N.N.
2014, Tim
e-do
main G
reen f
unctio
n soluti
on for
tra
nsien
telec
tromagn
etic
field.
Chinese
Jour
nal g
eophysics
,57(2
:671-678
)Z
hou
Nan-n
an, X
ue Gu
o-qia
ng, W
ang He-
yuan
. Compa
rison
of
the time
-doma
in el
ectro
magne
ticf
ield from
an inf
initesimal point
char
ge and
dipole
sour
ce. App
lied
Geophysics,
2013,10(
3):349-356Ziolko
wski A
, Hobbs B. A, W
right D
(2007)
Multi-t
ransie
nt el
ectromagnetic demo
nstrati
on s
urvey
in F
ranc
e.Geoph
ysics
72: 197-
209.Slide23
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