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GLE 2024 (Day 3) > GEOPHYSICS (ELECTRICAL SKEMANG) > Flashcards

GEOPHYSICS (ELECTRICAL SKEMANG) Flashcards

1
Q

Electrical Conductivity

A

Ability to let energy flow

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2
Q

Electrical Resistivity

A

Ability to deflect energy flow

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3
Q

Electrical Potential

A

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

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4
Q

Electric Potential Difference

A

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

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5
Q

What is measured in Electrical Surveys?

A

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

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6
Q

Conductive Causative Bodies

A

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

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7
Q

High resistive body

A

Quartz Veins

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8
Q

Three types of Geoelectrical Survey

A

?Electric Resistivity
?Induced Polarization
?Self Potential

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9
Q

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

A

Resisitivity Method

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10
Q

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

A

Resisivity

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11
Q

Electrical Resistivity Formula

A

Resistance = (Resistivity*Length)/Cross Area

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12
Q

Most rock forming minerals are (Conductors or Insulators)

A

Insulators

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13
Q

How is electric current carried through a hard rock?

A

Through pore waters

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14
Q

Properties which govern reisitivity of rock

A

Porosity (Inverse)
Degree of Saturation (Direct)

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15
Q

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

A

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

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16
Q

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

A

Schlumberger Array (C1—P1-P2—-C2)

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17
Q

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

A

Dipole Dipole (C1–C2——-P1–P2)

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18
Q

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

A

Gradient Arrays

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19
Q

Three types of Electrode Configuration

A

1)Werner
2) Schlumberger
3) Dipole Dipole

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20
Q

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

A

Vertical Electrical Sounding or Electrical Drilling

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21
Q

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

A

Constant Separation Technique.Traversing / Electrical Profiling

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22
Q

Type of Electrical Resitivity Surveys

A

Vertical Electrical Sounding or Electrical Drilling
Constant Separation Technique

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23
Q

both a current meter and voltmeter

A

Resistivity Meter

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24
Q

What can resistivity survey detec?

A

Very Low Levels of Resistance with high accuracy

25
Q

Frequency for Shallow probes

A

100 hz

26
Q

Frequence for deeper probes

A

10 Hz

27
Q

Units of Resitivity?

A

Ohm-Meter

28
Q

Economics of resisitivy surveys

A

Light, Portable, INEXPENSIVE, Felxible at minimal fixed expense

29
Q

Interpretation of Data

A

Rapid and Straghtforward

30
Q

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

A

No because laborious

31
Q

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

A

Clay

32
Q

Base Metal Sulfide that are not so conductive

A

Sphalerite

33
Q

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

A

Telluric Current

34
Q

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

A

Induced Polarization

35
Q

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

A

Time-Domain Induced Polarization

36
Q

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

A

Frequency-Domain Induced Polarizaion

37
Q

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

A

Membrane/Electrolytic Polarization

38
Q

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

A

Electrode Polarization or Overvoltage

39
Q

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

A

Disseminated Sulfide Ore Body

40
Q

Measured Parameter

A

Chargeability (ms)

41
Q

Units of measurement of Chargeability

A

milliseconds

42
Q

Common method of presenting IP Data

A

Pseuosection

43
Q

Electrode configuration usually used in IP Reconnaissance

A

Gradient

44
Q

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

A

Self Potential or Spontaneous Polarization

45
Q

What is the requirement of SP?

A

Causative Body must be near the water table

46
Q

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

A

Top of the orebody

47
Q

What type of anomaly is expected over metallic ore deposits?

A

Central Negative Anomaly

48
Q

Survey equpiments

A

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

49
Q

Mining and Econ Geol

A

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

50
Q

Hydrogeol

A

Hydrogeo effetiveness of water engg remedial emasures

51
Q

Environmental and Engg

A

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

52
Q

Mining and Econ Geol

A

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

53
Q

Structural

A

Overburden Thickness

54
Q

Hydrogeol

A

Hydrogeological Investigation

55
Q

Environmental and Engg

A

Engg Geological inbestigation before construction

56
Q

Mining and Econ Geol

A

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

57
Q

Hydrogeol

A

Hydrogeophysical

58
Q

Environmental and Engg

A

Environmental
Geotechnical

GLE 2024 (Day 3) (48 decks)

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