petunjuk penggunaan ARES

Short guide for resistivity and induced polarization imaging

Address of the manufacturer:

GF Instruments, s.r.o.

Jecna 29a

62100 Brno

tel: +420 541 634 285

fax: +420 549 522 915

e-mail: [email protected]

mailto:[email protected]

Short guide for resistivity imaging

Chapter 1

Comparison of main methods of 2D imaging

The comparison of main 5 methods used for 2 D imaging will be

shown in this chapter. This short overview can help with the

choice of optimum solution with the respect to the studied

problem. A comparison of important basic features in the frame of

these 5 methods is offered. This comparison is illustrated by

attached pictures from measurements with the use of individual

methods.

Schlumberger

Purpose

General purpose method covering broad range of tasks especially

imaging of horizontal and quasi-horizontal (declined) layers.

Detection of larger inhomogenities of various shape and direction

like wider crackles, tectonic zones, ore veins and contacts of

layers with big difference of resistivities is also effective.

Section covering Medium depth range - of about 1/5 of the maximum used C1C2

distance. Medium side covering.

Resolution

Medium resolution - sufficient rather for detailed investigation of

shallow structures.

Measuring conditions

Commonly used method for various ground resistivities. Lower

resistance against electric noise is caused by lower level of

measured potentials.

Wenner

Purpose

The fastest method. The most frequent variant called Wenner

alpha is close to Schlumberger with similar range of applications.

Other variants called Wenner beta (like Dipole-Dipole) and

Wenner gamma (non conventional array) are used rarely.

Section covering

Low depth range – of about 1/6 of the maximum used C1C2

distance. Low side covering.

Resolution

Low resolution – inconvenient for detailed investigation of deeper

structures.


High resistance against electric noise – effective replacement of

Schlumberger at places hit by electric noise.

Dipole-Dipole

Purpose

The most detailed method especially for detection of vertical

structures (including slimmer fissures, ore veins) and cavities.

Section covering

Medium depth range – of about 1/5 of the maximum used C1C2

distance. Medium side covering.

Resolution

The highest resolution – allows the maximum possible

distinguishing of deeper situated structures.


The effective depth range is strongly limited by rapid decrease of

measured potential at larger dipole distance. Artificial electric

noise causes additional significant limitation of use of this

method.

Pole-Dipole

Purpose

The most effective method for detection of all vertical structures

(even slim crackles) with high depth range.

Section covering

High depth range – of about 1/3 of the used length of the electrode

array. Higher side covering.

Resolution

Higher resolution. The accuracy of positions in section is

decreased (side shift) as the method is non symmetric. For better

results (regarding positions) it is recommended to use an

additional Reverse Pole-Dipole or to use Combined Pole-Dipole

instead.


Installation of external current electrod C2 (C1 in the case of

reverse way) – called infinite – is necessary. The place of infinite

electrode must be at least at the distance of 5 multiple of the

maximum length of used electrode array. Its optimum position

should be in perpendicular direction from the electrode array. The

big distance of infinite current electrode requires maximum power

of the transmitter and careful installation of such an electrode (or

even electrode nest) to reach its lowest possible ground resistance.

Pole-Pole

Purpose

The most effective method for investigation of deep structures (all

kinds). Rarely used.

Section covering

The highest depth range almost 70 % of the length of the electrode

array. The highest side covering.

Resolution

Medium resolution.


Installation of two external electrodes (C2 and P2) – called

infinites – is necessary. The preparation of the measurement is the

most time consuming with the highest requirement regarding the

available free area around the measuring line. Each infinite

electrode must be at least at the distance of 5 multiple of the

maximum length of used electrode array. Their optimum position

should be in perpendicular direction from the electrode array. C2

and P2 should be on opposite sides of the electrode array. The big

distance of infinite current electrode requires maximum power of

the transmitter and careful installation of such an electrode (or

even electrode nest) to reach its lowest possible ground resistance.

The length of the measured profile: 31 m Profile: 20

Number of electrodes: 32 (4 sections)

Comparison of sections measured on the same line using different methods (electrode arrays)

This way it is possible to judge differences in section covering (depth and side ranges) and resolution (density of measured points).

Resistivity in ohm.m


0 5 10 15 20 25 30

6

4

2

0

Ps.Zm.

Measured Apparent Resistivity Pseudosection Unit electrode spacing 1 m.

C1 P1 P2 C2a a aa). Wenner Alpha

0 5 10 15 20 25 30

-5

-3

-1

Dep

th (

m)

Unit electrode spacing 1 mInverse Model Resistivity Section

m.

Iteration 5 RMS error = 1.4 %

b). Schlumberger

0 5 10 15 20 25 30

6

4

2

0

Ps.Zm.


C1 P1 P2 C2na a na

0 5 10 15 20 25 30

-5

-3

-1

Dep

th (

m)

m.Iteration 5 RMS error = 0.96 %



0 5 10 15 20 25 30

6

4

2

0

0

Ps.Zm.

c). Dipole-Dipole C2 C1 P1 P2a na a


-6

-4

-2

Dep

th (

m)


0 5 10 15 20 25 30 m.


d). Pole-Dipole C2

C1 P1 P2na a


0

0 5 10 15 20 25 30

10

5

0

Ps.Z m.


-6

-8

-10

-4

-2

Dep

th (

m)


0 5 10 15 20 25 30 m.Iteration 5 RMS error = 1.15 %

0 5 10 15 20 25 30

25

20

15

10

5

0

Ps.Z m.

e1). Pole-PoleP2C2

C1 P1a



e2). Pole-PoleP2C2

C1 P1a


0 5 10 15 20 25 30 m.0

-15

-20

-25

-10

-5

Dep

th (

m)



e2). Pole-PoleP2C2

C1 P1a

0 5 10 15 20 25 30

-6

-4

-2

0

Dep

th (

m)

m.

c). Wenner Gamma


0 5 10 15 20 25 30

-5

-3

-1

Dep

th (

m)

m.

b). Wenner BetaIteration 5 RMS error = 1.29 %


0 5 10 15 20 25 30

-5

-3

-1

Dep

th (

m)






m.

a). Wenner AlphaIteration 5 RMS error = 1.4 %

C1 P1 P2 C2a a a

C2 C1 P1 P2a a a

C1 P1 C2 P2a a a

The length of the measured profile: 31 m Profile: 20

Number of electrodes: 32 (4 sections)

Comparison of sections measured on the same line

using different Wenner methods (alpha, beta, gamma)

In the following pictures different depth ranges, resolutions and sensitivities to the structure are obvious.

Examples of typical applications

Hydrogeology

This wide area of resistivity imaging applications includes various

tasks:

- water management and protection

- environmental monitoring

- impacts in civil engineering

Engineering geology

This area connected with the construction and maintenance of

buildings, roads, railways and bridges requires judgement of:

- bedrock surface

- slope stability

- landslide risk

- detailed geological structure

- mechanical properties of rocks, sediments etc.

Geological mapping

General survey for geological studies covers:

- raw material prospecting

- geological survey

- complex judgement of strategic localities

- choice of places for dangerous waste materials

10

18

.233

.26

0.5

11

0.3

201

.1366

.46

67.8

Res

isti

vit

y i

n o

hm

.m

020

40

60

80

100

12

01

40

-50

-50

-40

-40

-30

-30

-20

-20

-10

-10

00

Inver

se M

od

el

Res

isti

vit

y S

ecti

on

U

nit

ele

ctro

de

spac

ing

3.0

m

m.

Depth (m)

Iter

atio

n 4

RM

S

erro

r =

6.8

%

S-

Rock

su

rfac

e

G-

Gn

eiss

G

G

SS

Pro

ject

ing

of

wate

r w

ell

Deta

iled

geolo

gic

al i

nfo

rmati

on f

or

loca

tin

g, d

rill

ing a

nd

buil

din

g o

f w

ater

wel

l w

as r

eq

uir

ed.

Th

e p

reli

min

ary i

dea

of

the

surv

ey

was

bas

ed o

n m

ap

pin

g o

f te

cto

nic

zo

nes

and w

eath

ered

rock

s.

Due t

o t

he

nee

ded

rat

her

hig

h d

epth

rang

e and

res

olu

tio

n P

ole

-Dip

ole

met

ho

d w

as c

hose

n (

infi

nit

e el

ectr

ode

C2

at

x =

50 m

an

d

y =

60

0 m

).

Th

e p

ictu

re s

ho

ws

the

posi

tion

of

a w

ide

fault

fil

led

wit

h p

erm

eable

wea

there

d r

ock

s co

nv

enie

nt

for

buil

din

g o

f th

e w

ell

wit

h r

ich w

ate

r su

pp

ly.

05

10

15

20

-4-4

-2-2

00

Iter

atio

n 4

RM

S e

rro

r =

2.3

%

m.

10

14

18

22

26

30

34

38

40

Res

isti

vit

y i

n o

hm

.m

Un

it e

lect

rod

e s

pacin

g 1

.0 m

Invers

e M

od

el R

esi

stiv

ity S

ect

ion

Depth (m)

Depth (m)

B-

Zone

of

conta

min

atio

n w

ith l

iquid

man

ure

- B

ackfi

ll -

san

d a

nd g

ravel

En

vir

on

men

tal

pro

tect

ion

A c

om

ple

x m

onit

ori

ng i

n t

he

fram

e of

gro

un

d w

ater

pro

tect

ion i

n c

lose

vic

init

y o

f a

pig

far

m

was

do

ne.

The

goal

of

the

resi

stiv

ity i

magin

g w

as t

o d

etec

t le

akage f

rom

a l

iquid

man

ure

tan

k.

Sch

lum

ber

ger

arr

ay w

as u

sed

.

Under

th

e b

ackfi

ll c

reat

ed b

y s

and

and

gra

vel

a z

one

wit

h s

ignif

ican

tly d

ecre

ased

res

isti

vit

y i

s

seen

. T

hes

e ex

trem

ely l

ow

val

ues

of

resi

stiv

ity a

re t

ypic

al f

or

the

hig

h c

onta

min

atio

n w

ith

org

anic

su

bst

ance

s.

25

45

65

85

10

51

25

14

51

65

05

10

15

20

25

30

35

40

45

-10-8-6-4-20

Res

isti

vit

y i

n o

hm

.m

Invers

e M

od

el R

esis

tivit

y S

ect

ion

U

nit

ele

ctr

od

e sp

acin

g 0

.500

mm.

Depth (m)

Itera

tio

n 5

RM

S

err

or

= 0

.44

% E

luviu

m (

dry

) W

ater

sat

ura

ted

zone

San

dst

one

Pro

tect

ion

of

bu

ild

ing

Wal

ls o

f a

bu

ildin

g a

s w

ell

as c

ella

rs w

ere

par

tial

ly h

it b

y w

ater

com

ing t

o i

ts i

nsu

ffic

ientl

y

insu

late

d b

asem

ent.

Th

e s

urv

ey f

or

det

erm

inati

on o

f w

ater

ed z

ones

alo

ng

this

buil

din

g w

as

per

form

ed.

Sever

al p

rofi

les

in t

he

vic

init

y o

f th

e bu

ildin

g w

ere

mea

sure

d. S

chlu

mber

ger

arr

ay

was

use

d.

The

pic

ture

show

s la

rge

wat

ere

d z

one

wit

h s

ignif

ican

tly d

ecre

ased

res

isit

ivit

y i

n t

he

left

par

t.

The

exac

t p

osi

tion

of

the

mai

n w

ater

infi

ltra

tion

is

obv

ious

at p

osi

tion

P.

020

40

60

80

100

120

140

160

160

170

170

180

180

165

165

175

175

10

15

.925

.240

63

.51

01

160

25

4

Res

isti

vit

y i

n o

hm

.m

Invers

e M

od

el R

esis

tivit

y S

ect

ion

U

nit

ele

ctro

de s

paci

ng 2

mm.

Elevation

The

way

of

wat

er i

nfi

ltra

tio

n d

uri

ng t

he

hig

h w

ater

lev

el.

Riv

er d

ike

inves

tigati

on

In t

he

fram

e of

the

pro

tect

ion a

gai

nst

flo

ods

the r

iver

dik

e q

ual

ity a

nd s

tabil

ity w

ere

monit

ore

d. T

hus

a pro

file

alo

ng t

he

dik

e an

d a

den

se g

rid o

f pro

file

s p

erpen

dic

ula

rly t

o t

he

riv

er w

ere

mea

sure

d.

Sch

lum

ber

ger

arr

ay w

as u

sed

.

The

pic

ture

co

min

g f

rom

one

of

pro

file

s in

per

pen

dic

ula

r dir

ecti

on

to t

he

river

show

s both

the

geo

logic

al s

truct

ure

and t

he

bas

e and

str

uct

ure

of

the a

rtif

icia

l dik

e. T

he h

uge

allu

viu

m g

ravel

lay

er

allo

ws

quic

k w

ate

r in

filt

rati

on b

elow

th

e dik

e i

n t

he

cas

e of

hig

h w

ater

lev

el. T

he

mate

rial

of

the d

ike

sho

ws

bo

th i

nhom

ogen

ous

stru

cture

and

per

mea

ble

bas

emen

t w

hic

h l

ead

s to

its

malf

un

ctio

n i

n t

he

case

of

flood

(q

uic

k o

ccurr

ence

of

wat

er o

n f

ield

s beh

ind

the

dik

e).

10

22

.550.6

113

.925

6.2

576.6

1297

.4291

9.3

Res

isti

vit

y i

n o

hm

.m

420

420

430

430

440

440

450

450

460

460

470

470

480

480

490

490

500

500

510

510

520

53

0

520

53

0

20

40

60

80

100

120

140

160

180

200

22

0

24

0

260

28

0

Inver

se M

od

el

Resi

stiv

ity S

ecti

on

U

nit

ele

ctr

ode

spac

ing 4

m

m.

Elevation

Elevation

S

S

S

Bed

roc

k s

urf

ac

e

La

nd

slid

e ri

sk j

ud

gem

ent

Map

pin

g o

f th

e d

epth

of

the

deb

ris

for

dam

sta

bil

ity m

onit

ori

ng w

as d

one

on a

slo

pe

of

river

val

ley c

lose

to t

he

dam

. S

chlu

mber

ger

arra

y w

as u

sed.

The

pic

ture

show

s th

e depth

and s

hap

e of

old

lan

dsl

ide

crea

ted b

y s

tones

and c

oar

se s

andst

one

deb

ris.

Het

ero

geneo

us

stru

cture

of

the

bed

rock

par

tial

ly s

atura

ted w

ith w

ater

fro

m t

he

dam

is

ob

vio

us

as w

ell.

San

dst

one

loca

lly w

ith

th

in c

layst

one

layer

s

Map

pin

g s

lop

e d

efo

rmati

on

A r

oad

in

mou

nta

ins

was

fat

ally

des

troyed

by a

ctiv

e l

andsl

ide

(as

a co

nse

qu

ence

of

hea

vy

rain

). D

etai

led m

onit

ori

ng o

f th

e sl

ope

was

per

form

ed b

efore

the

road

rec

onst

ruct

ion

.

Sch

lum

ber

ger

arr

ay w

as u

sed

.

The

pic

ture

sho

ws

the

thic

kn

ess

and s

hap

e of

the

wat

ered

zo

ne

wit

h r

isk o

f th

e m

assi

ve

conti

nuou

s la

ndsl

ide. T

he

bed

rock

is

cre

ated

by c

lay

stone

and

san

dst

one. T

he

posi

tion o

f an

old

dry

lan

dsl

ide

is s

een a

t po

siti

on D

as

wel

l.

10

450

45

0

455

45

5

460

46

0

465

46

5

470

47

0

30

40

50

60

20

Elevation

Elevation

Inv

erse

Mod

el

Resi

stiv

ity S

ecti

on

U

nit

ele

ctro

de

spac

ing

1 m

m.

69

12

15

18

21

24

27

Res

isti

vit

y i

n o

hm

.m

Wet

sed

imen

ts -

zo

ne

of

satu

rati

on

S S

lip s

urf

ace

- bas

e of

no

n s

oli

d g

roun

d

010

20

30

40

50

60

70

80

90

100

-10-8-6-4-20

20

30

40

50

60

70

80

90

Res

isti

vit

y i

n o

hm

.m

Invers

e M

od

el R

esis

tivit

y S

ect

ion

U

nit

ele

ctro

de s

paci

ng

1.5

0 mm

.

Depth (m)

Iter

atio

n 5

Ab

s.

erro

r =

1.6

1 %

Roo

f fa

ll

Cel

lars

Unbro

ken

BB

ack

fill

C C

lay

A B

ase

of

dis

turb

ed a

rea

Road

Cel

lar

Asp

hal

t ro

ad

Mo

nit

ori

ng s

lop

e st

ab

ilit

y a

bo

ve

cell

ars

The

are

a ab

ove

a q

ueu

e o

f w

ine

cell

ars

was

endan

ger

ed b

y u

npre

dic

table

mov

emen

t of

inst

able

soil

that

occ

urr

ed a

s a

conse

quen

ce o

f co

llap

se o

f so

me

cell

ars.

House

s an

d a

sphal

t

road

on t

hat

pla

ce w

ere

par

tial

ly d

estr

oyed

. T

he

surv

ey s

hou

ld d

etec

t w

eak z

ones

, hole

s an

d

wast

e m

ater

ial

dep

osi

ts i

n t

he s

lope.

Sch

lum

ber

ger

arra

y w

as u

sed.

Man

y i

nho

mo

genit

ies

(cav

itie

s, b

ack

fill

) are

vis

ible

in l

eft

par

t of

the

pic

ture

. T

hey

det

erm

ine

the

zone

of

the

slo

pe

inst

abil

ity.

The

cell

ars

in t

he

right

par

t o

f th

e p

ictu

re a

re s

ituat

ed i

n s

oli

d

rock

and

are

not

endang

ere

d b

y c

oll

apse

.

20

25

30

35

40

45

50

55

-6-4-20

Inverse

Mod

el

Res

isti

vit

y S

ect

ion

U

nit

ele

ctro

de

spaci

ng 1

m

m.

Depth (m)

Itera

tio

n 3

RM

S e

rror

= 5

.4 %

K1

K2

K3

Cavity c

ontinu

ation

Know

n c

avity p

art

ially

repaired

New

dis

cover

ed c

avit

y

10

30

50

70

90

11

01

30

15

0

Res

isti

vit

y i

n o

hm

.m

Map

pin

g c

av

itie

s

A f

ishpond

dam

was

par

tial

ly d

estr

oyed

duri

ng

the

flood. T

he

surv

ey w

as p

erf

orm

ed t

o d

etec

t

its

wea

k p

lace

s. S

chlu

mber

ger

arr

ay w

as m

easu

red a

long t

he

dam

.

The

sect

ion

sh

ow

s th

ree

mai

n a

reas

fil

led w

ith m

ud f

rom

th

e fi

shpond (

taken

duri

ng t

he

floo

d).

Th

eir

posi

tio

ns

are p

arti

all

y v

isib

le i

n s

itu b

ecau

se t

hey

are

acc

om

pan

ied w

ith

dep

ress

ions

of

the

dam

.

Unit

Ele

ctro

de

Sp

acin

g =

1.0

m

Elevation

Elevation

100

100

102

102

104

104

106

106

108

108

110

110

112

112

114

114

116

116

118

118

Mo

del

resi

stiv

ity w

ith

to

pog

rap

hy

Iter

atio

n

4 R

MS

e

rror

= 4

.1

m.

10

20

30

40

10

16

25

40

63

10

11

60

25

4R

esis

tivit

y i

n o

hm

.m.

Inv

ers

e M

od

el R

esi

stiv

ity

Sect

ion

B

BB

edro

ck s

urf

ace

Sil

ty l

oam

+E

luv

ium

Gra

no

dio

rite

Inves

tigati

on

of

the

rock

su

rface

Th

e ro

ck s

urf

ace

(gra

nodio

rite

) w

as i

nvest

igat

ed b

efore

pro

ject

ing o

f bas

em

ents

of

house

s.

Sch

lum

ber

ger

arr

ay w

as u

sed.

The

shap

e of

incl

ined

bed

rock

as

wel

l as

the

wea

ther

ed l

ayer

above

are

ver

y w

ell

vis

ible

fro

m

the p

ictu

re.

b). Minimum electrode spacing 1 m

a). Minimum electrode spacing 2 m

0 20 40 60 80

208

212

216

220

Ele

vat

ion

10 14 18 22 26 30 34 38


Inverse Model Resistivity Section Unit electrode spacing 1 m

m.

Sandy developments Clay sediments Geoelectrical boundary

0 20 40 60 80

208

212

216

220

Ele

vat

ion

m.

10 14 18 22 26 30 34 38Resistivity in ohm.m

Inverse Model Resistivity Section Unit electrode spacing 2 m

Mapping resistivity contact

General geological mapping was performed to determine the safearea for a large building construction. The task was to give an exactinformation about the square and depth of homogenous geological structure. Schlumberger array was used.

The picture shows the border between homogenous clay sedimentand inhomogeneous area created by sandy and clayey sediments.(These two pictures demonstrate the fact that for this purpose the increased spacing - 2 m instead of 1 m - gives very similar results.)

10

30

50

70

90

11

01

30

15

0

Res

isti

vit

y i

n o

hm

.m

020

40

60

80

10

012

01

40

160

-8-6-4-20

Inv

ers

e M

od

el R

esi

stiv

ity

Sect

ion

U

nit

ele

ctro

de s

pac

ing

1.0

0 mm

.

Depth (m)

Iter

atio

n 4

RM

S

erro

r =

5.3

%

BAA

lluv

ium

sed

imen

ts -

cla

yey

sil

t

Bbac

kfi

ll -

buil

din

g g

arbag

e, c

oncr

ete

blo

cks,

rec

ycl

ing m

ater

ials

Map

pin

g b

ack

fill

Th

e b

ackfi

ll t

hic

knes

s w

as

det

erm

ined

by m

eans

of

resi

stiv

ity i

mag

ing. S

chlu

mberg

er a

rray

was

use

d.

It i

s p

oss

ible

to s

ee v

ery h

om

ogen

ous

bed

rock

(cl

ayey

sil

t) c

overe

d b

y a

ppro

x. 2 m

bac

kfi

ll.

Th

e b

ackfi

ll s

how

s ver

y i

nhom

ogen

eous

stru

cture

(b

uil

din

g w

aste

mate

rial

, co

ncr

ete

blo

cks

and r

ecycl

ing

mat

eria

l).

Dry cracked claystone at the surface

Claystone

Sandstone

Near-surface inhomogeneous layer- sand and insulated dissemination of metallic sulfides (pyrite)

b). Minimum electrode spacing 0.8 m

a). Minimum electrode spacing 0.4 m

0 10 20 30 40

-5

-3

-1

Dep

th (

m)

m.

50 60 70 80 90 100 110 120 125



Inverse Model Resistivity Section Unit electrode spacing 0.4 m

0 10 20 30 40

-5

-3

-1

Dep

th (

m)

m.

50 60 70 80 90 100 110 120 125Resistivity in ohm.m


Unit electrode spacing 0.8 mInverse Model Resistivity Section

D

D

Thin horizontal layer survey

The task was to determine a thin inhomogeneous layer (of approx.1 m) in the ceramic clay quarry. Schlumberger array was used.

The detected inhomogeneous layer of sandstone with pyrite wasspread horizontally at about 1 m depth.(These two pictures demonstrate the necessity of the sufficientdensity of electrodes - decreased spacing - for required resolution.)

Short guide for induced polarization imaging

Chapter 2

General features and purpose of IP measurement

Measurement of induced polarization allows distinguishing

structures according to their chargeabilities and can be used as

complementary method for resistivity imaging. Thus we can

obtain useful information from simultaneous sections of

resistivity, chargeability and metal factor (defined as ratio of

chargeability and resistivity). This comparison is useful for

judgment of structures when metal ore layer (with first order

conductor), water table or influence of artificial substances (like

oil, organic and inorganic chemicals) are supposed and studied.

Physical background

To understand physical basis of this method comparison with

simple and well known electric elements like resistor and

capacitor is useful. Some structures (e.g. dry sandy and crystalline

rocks) look like resistor rather than capacitor – the potential

induced during current pulse is rapidly lost (during several

milliseconds) when this pulse is terminated. Other structures (e.g.

metal ore layers) look like capacitor rather than resistor – the

potential induced during current pulse is kept for significant

period (during several seconds) when this pulse is terminated. The

decay curve of potential can sampled and sections from individual

sampling windows can be processed as chargeability (resp. as

metal factor).

Methodical reminders

IP measurement is not such a general method like resistivity

imaging, however, for special tasks can bring results that can be

hardly replaced by another geophysical method. Its proper

application requires deeper knowledge, the IP measurement takes

significantly longer time than resistivity. The choice of IP window

can influence selectivity to specific kinds of objects. Generally,

windows set to short times after pulse termination increase

selectivity to shallow situated and smaller objects while windows

set to longer times after pulse termination select bigger and deeper

situated objects.

Measuring instructions and settings

For IP measurement stainless steel electrodes are necessary.

The measured potential is necessary to be kept at the highest level

possible to suppress noise present at low measured potential and

causing big statistic deviation of IP readings. It means to set 200

mV optimum potential for IP measurement which activates the

maximum available transmitter power.

The first 20 ms IP window after pulse termination can be hit by

EM (electromagnetic) effect especially while longer cable line is

used. This effect can disturb responses of real objects.

Examples of typical applications

Following examples show results from raw material prospecting

and hydrogeology, which belong to basic areas of IP applications.

Environmental studies like leakage of oil and other mineral

substances can be supported by IP measurement as well.

Some important features of IP measurement are discussed in

individual pictures.

Ore Prospecting

Inverse Model Metal Factor Section Unit electrode spacing 2.0 m

Dep

th (

m)

Iteration 5 RMS error = 62.7

0

0

10

10

20

20

30

30

40

40

50

50

60

60

-10

-8

-6

-4

-2

0

IP 2 = 0.02 - 0.04 s

Inverse Model Chargeability Section Unit electrode spacing 2.0 m

m.

Depth

(m

)



m.

Depth

(m

)


m.

0 10 20 30 40 50 60

-10

-8

-6

-4

-2

0

20 29 41 60 86 124 178 257 519Resistivity in ohm.m

0 3 9 16 22 28 34 41 47 53 59 66 72 78 84 91 97 157

Chargeability in msec (= 0.1 %)

IP 2 = 0.02 - 0.04 s

-0.5-1.63-3.03

-4.79

-6.99

-9.73

500 700 900 1100 1300 1500 1700 1900Metal Factor in “0.001 msec/ohm.m”

Shallow situated ore deposit (former surface mines from 15 th century) was investigated using Schlumberger array.Chargeability section shows ore vein situated in weakened zone of rockcharacterized by lower resistivity (see resistivity section). Metal factorsection illustrates further possibility of selection of ore vein positionsdecreasing influence of changing resistivity.

0 3 9 16 22 28 34 41 47 53 59 66 72 78 84 91 97 157

IP Windows Selection

0 10 20 30 40 50 60

-10

-8

-6

-4

-2

0

IP 3 = 0.04 - 0.06 s


m.

Dep

th (

m)


0 10 20 30 40 50 60

-10

-8

-6

-4

-2

0

IP 2 = 0.02 - 0.04 s


m.

Dep

th (

m)


0 10 20 30 40 50 60

-10

-8

-6

-4

-2

0

IP 1 = 0.00 - 0.02 s


m.

Dep

th (

m)



This picture (accompanying the previous one) shows the crucial influence of IP windows position in pulse decay curve. Smaller and shallow situated objects are emphasized in first 20 ms IP window while next IP windows select weakened zone filled with ore vein.

Natu

ral

Gra

ph

ite D

ep

osi

t

050

10

01

50

20

02

50

-40

-30

-20

-100

IP 3

= 0

.04 -

0.0

6 s

Inv

erse

Mo

del

Ch

argea

bil

ity

Secti

on

U

nit

ele

ctr

od

e sp

acin

g 4

.0 m

m.

Depth (m)

Iter

atio

n 4

RM

S

err

or

= 7

.3

05

01

00

15

020

025

0

-40

-30

-20

-100

Inv

erse

Mo

del

Resi

stiv

ity

Secti

on

U

nit

ele

ctr

od

e sp

acin

g 4

.0 m

m.

Depth (m)

Itera

tio

n 4

RM

S

err

or

= 4

.0 %

15

30

60

12

02

40

48

09

60

192

0R

esis

tiv

ity

in o

hm

.m

20

50

80

11

01

40

17

02

00

23

0C

har

geab

ilit

y i

n m

sec (

= 0

.1 %

)

IP S

ecti

on

perf

orm

ed

abo

ve f

orm

er

dri

ft o

f g

raphit

e m

ine s

how

s posi

tion o

f dep

osi

t. P

osi

tion

of

the d

rift

as

well

as

rath

er

com

pli

cate

d g

eo

logic

al

stru

ctu

re a

re s

een f

rom

accom

pany

ing

resi

stiv

ity

secti

on.

0 20 25 31 39 49 61 76 95 119 149 186 233 291 363 455 568


0 10 20 30 40 50 60

-10

-8

-6

-4

-2

0


m.

Dep

th (

m)


Water Table Investigation

0 10 20 30 40 50 60

-10

-8

-6

-4

-2

0


m.

Dep

th (

m)


0 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40


IP 2 = 0.02 - 0.04 s

Basic geology of the site is created by quartz sand above claybackground visible in resistivity section.IP section shows slightly inclined water table at approximately3 m level in the sandy layer.

petunjuk penggunaan ARES

Documents