GEOPHYSICS (ELECTRICAL SKEMANG)

Question 1

Electrical Conductivity

Answer 1

Ability to let energy flow

Question 2

Electrical Resistivity

Answer 2

Ability to deflect energy flow

Question 3

Electrical Potential

Answer 3

Work done by moving a charge particle from infinity to other point

Question 4

Electric Potential Difference

Answer 4

Work done in carrying a unit positive charge from A to B while keeping the charge in equilibrium

Question 5

What is measured in Electrical Surveys?

Answer 5

Potential Difference through
Magnitude of current introduced and the variation in the receiving electrodes

Question 6

Conductive Causative Bodies

Answer 6

?Massive Sulfides
?Graphite Rich Beds
? Fractured/Altered zones with Confined water containig dissolved salts and clay

Question 7

High resistive body

Answer 7

Quartz Veins

Question 8

Three types of Geoelectrical Survey

Answer 8

?Electric Resistivity
?Induced Polarization
?Self Potential

Question 9

Used in the study of horizontal and vertical discontinuities in the electrical properties of the ground and the detection of 3D bodies of anomalous electrical donductivities

Answer 9

Resisitivity Method

Question 10

Resistance between opposite faces of unit cube and is one of the extremely variable physical properties of rocks

Answer 10

Resisivity

Question 11

Electrical Resistivity Formula

Answer 11

Resistance = (Resistivity*Length)/Cross Area

Question 12

Most rock forming minerals are (Conductors or Insulators)

Answer 12

Insulators

Question 13

How is electric current carried through a hard rock?

Answer 13

Through pore waters

Question 14

Properties which govern reisitivity of rock

Answer 14

Porosity (Inverse)
Degree of Saturation (Direct)

Question 15

Electrode configuration in which Current and Potenrial eletrodes are kept along a STRAIGHT LINE-EQUAL ARRAY SPACING “a”
Used in studying lateral variations most conveneient

Answer 15

Werner Array (C1-a-P1-a-P2-a-C2)

Question 16

Electrode Configuration in which distance between Potential Electrodes are smaller than that between Current Electrodes with the Ps sitting between or inside Cs

Answer 16

Schlumberger Array (C1—P1-P2—-C2)

Question 17

Electrode configuratio in which Potential Electrodes are outsie the Current electrodes with both pair having equal distance

Answer 17

Dipole Dipole (C1–C2——-P1–P2)

Question 18

Type of Configuration in which the outer current electrodes are fixed and far apart while the Closer inner electrodes are moved together

Answer 18

Gradient Arrays

Question 19

Three types of Electrode Configuration

Answer 19

1)Werner
2) Schlumberger
3) Dipole Dipole

Question 20

A type of Electrical Resistivity surverying wherein current and potential electrodes are retained in a straight line at same relative spacing around a fixed central Points point pressuming that current penetrates continuously deeper

Useful for determining loose horizontal overburden thickness over hard rocks

Answer 20

Vertical Electrical Sounding or Electrical Drilling

Question 21

A type of Resistivity survey wherein an electrode spread (A setup of Current and Potential electrodes) is progressively moved while maintaing electrode separation along a traverse line.

Employed in mineral exploration to locate faults and shear zones

Answer 21

Constant Separation Technique.Traversing / Electrical Profiling

Question 22

Type of Electrical Resitivity Surveys

Answer 22

Vertical Electrical Sounding or Electrical Drilling
Constant Separation Technique

Question 23

both a current meter and voltmeter

Answer 23

Resistivity Meter

Question 24

What can resistivity survey detec?

Answer 24

Very Low Levels of Resistance with high accuracy

Question 25

Frequency for Shallow probes

Answer 25

100 hz

Question 26

Frequence for deeper probes

Answer 26

10 Hz

Question 27

Units of Resitivity?

Answer 27

Ohm-Meter

Question 28

Economics of resisitivy surveys

Answer 28

Light, Portable, INEXPENSIVE, Felxible at minimal fixed expense

Question 29

Interpretation of Data

Answer 29

Rapid and Straghtforward

Question 30

Is Electrical Resistivity suitable for reconnaissance, Why or Why not?

Answer 30

No because laborious

Question 31

Mineral that are electrically polarized which can make rocks containing them highly conductive even when slightly moist

Answer 31

Clay

Question 32

Base Metal Sulfide that are not so conductive

Answer 32

Sphalerite

Question 33

Natural electric current on the ground that flow parallel to the Earths surface and caused regional potential Gradients

Answer 33

Telluric Current

Question 34

Imaging Technique that identified ELECTRICAL CHARGEABILITY of subsurface Materials (Ore Bodies)

Answer 34

Induced Polarization

Question 35

The measurement of Decaying volatage (as the ground acts as a capacitor and becoms electrically polarized) over a certain time interval

Answer 35

Time-Domain Induced Polarization

Question 36

In an induced low frequency alternating current, resisitivity of subsurface decreaseases as frequence is increased (Resitivity down, AC frequency Up)

Answer 36

Frequency-Domain Induced Polarizaion

Question 37

Effect in which Non Metallic Minerals, upon imposition of external current flow becomes additionally charged and such voltage decays as the source is switched off

Answer 37

Membrane/Electrolytic Polarization

Question 38

Effect in Metallic Minerals upon imposition of external current flow through pore fluids caused transitory decaying voltage

Answer 38

Electrode Polarization or Overvoltage

Question 39

Type of Ore that is perfect to be subject under Induced Polarization since Electrode Polarization will be more efficient in large surface area orebodies

Answer 39

Disseminated Sulfide Ore Body

Question 40

Measured Parameter

Answer 40

Chargeability (ms)

Question 41

Units of measurement of Chargeability

Answer 41

milliseconds

Question 42

Common method of presenting IP Data

Answer 42

Pseuosection

Question 43

Electrode configuration usually used in IP Reconnaissance

Answer 43

Gradient

Question 44

A method that is base on natural potential differences resulting from electrochemical reactions in the subsirface and is unique because it is passive, non instrusive, non destructive and does not require introduction of external current

Answer 44

Self Potential or Spontaneous Polarization

Question 45

What is the requirement of SP?

Answer 45

Causative Body must be near the water table

Question 46

What part of the causative body especially metallic ore deposits are negatvely charge or acts as negative terminal?

Answer 46

Top of the orebody

Question 47

What type of anomaly is expected over metallic ore deposits?

Answer 47

Central Negative Anomaly

Question 48

Survey equpiments

Answer 48

Pair of NonPolarizing Porous Pot Electrode Connected via a millivoltmeter Electrodes are composed of simple metal spikes immersed in solution of its own salt

Question 49

Mining and Econ Geol

Answer 49

Massive sulfide Orebodies (Magnetite or Graphite) Reconnaissance for Base Metals Prospecting for Geothermal Downhole logging in Oil industry

Question 50

Hydrogeol

Answer 50

Hydrogeo effetiveness of water engg remedial emasures

Question 51

Environmental and Engg

Answer 51

Identification of seepages in dams and reservoirs Finding leaks in Cancal Enbankments

Question 52

Mining and Econ Geol

Answer 52

Exploration for sulfide deposits (Massive Cu, Ni, Au-g) Extents of Deposit of Bulk Minerals (Clay and Gravel) Geotthermal Resource

Question 53

Structural

Answer 53

Overburden Thickness

Question 54

Hydrogeol

Answer 54

Hydrogeological Investigation

Question 55

Environmental and Engg

Answer 55

Engg Geological inbestigation before construction

Question 56

Mining and Econ Geol

Answer 56

?Low-grade Ore Deposits (disseminated) PCDs ?Placer Deposits ?Base Metal Exploration (Both massive and disseminated)

Question 57

Hydrogeol

Answer 57

Hydrogeophysical

Question 58

Environmental and Engg

Answer 58

Environmental Geotechnical