Resistivity

1. What is the difference between resistance and resistivity?

2. How is resistivity defined?

3. By what process do most rocks conduct electricity?

4. How are resistivity and porosity related?

5. How does the electrode separation affect the depth of current penetration?

6. If the electrode separation is 60 meters, approximately what proportion of the current will flow below a depth of 10 meters?

7. You plan to conduct a resistivity survey in an area containing overburden. You want to at least 70% of the current to flow beneath the overburden. From a single test drill hole you have determined that the overburden is 5 meters thick. What is the minimum separation the electrodes should have?

8. What do the abbreviations CST and VES stand for?

9. Describe CST and VES surveys.

10. Describe the differences between a Wenner and Schlumberger survey.

11. For each type of survey, how would you calculate the resistivity?

12. Why do most resistivity surveys use alternating current rather than direct current?

13. How would you choose the AC frequency when conducting a resistivity survey?

14. What technological improvements have been made to allow for rapid surveys which require only shallow depth penetration?

15. How would you construct and interpret data from a VES survey where there are only two horizontal layers?

16. How do VES profiles look for the 3-layer case?

17. What is the difference between a longitudinal and transverse (broadside) traverse?

18. What would the profiles of a Wenner longitudinal and transverse traverse look like over a vertical contact between two bodies with different resistivities?

19. For each of the above surveys, how would you locate the point of contact?

20. Figure 8:17: Is the limestone or the sandstone a better conductor of electricity?

21. Figure 8:19: Is the shale or the limestone a better conductor?

22. What are the limitations of resistivity surveys?

23. Describe some of the applications of resistivity surveys.

Induced Polarization (IP)

1. What is meant by the term capacitance?

2. How does the capacitance of the ground affect apparent resistivity measurements?

3. Describe the process of induced polarization.

4. What is the difference between time-domain and frequency-domain IP?

5. Describe the two methods of induced polarization.

6. Which minerals contribute to the electrode polarization effect?

7. What factors affect the magnitude of the electrode polarization effect?

8. What is meant by the term “chargeability”? How is it calculated?

9. What is meant by the term “percentage frequency effect”? How is it calculated?

10. What is meant by the term “metal factor”? How is it calculated?

11. What is a pseudosection? How is it created?

12. What factors contribute to noise in an IP survey?

13. What is the main application for IP surveys?

Self-potential (SP)

1. What units of measurement are used to describe SP surveys?

2. What are typical amplitudes of SP anomalies?

3. What types of deposits are usually detected by SP surveys?

4. Describe the mechanism of self-potential.

5. What type of equipment is used in an SP survey?

6. What are typical survey procedures?

7. How are SP anomalies interpreted?