1. How was the spontaneous potential discovered? why is it an electrical phenomenon? 2. What are the units of SP? 3. Under which conditions would the SP potential be positive, negative, or zero? 4. Define diffusion, membrane, and streaming SP potential. 5. What is the definition of static SP? 6. What are the necessary conditions for the existence of diffusion and membrane potentials? 7. What is ion mobility? What physical variables determine the mobility of an ion in an aqueous solution? 8. Why dont oil-base muds support SP potentials? 9. Why arent the SP readings across carbonate rocks zero (null)? 10.Why do SP logs drift with respect to depth? 11.What is static SP (SSP)? 12.Why are SP readings positive or negative? When is the SP reading positive and when negative? 13.What is the relationship between the electrical resistivity of connate water and the SSP measured across a clean sand bed? 14.Do SP logs detect the solid or the fluid component of a permeable and porous rock? 15.Are SP measurements sensitive to invasion? 16.What is the length of investigation of an SP log? 17.What is the effect of increased clay concentration on the SP reading across a sand bed? 18.What is the effect of increased hydrocarbon concentration on the SP reading across a bed? 19.Why is it sometimes said that the SP log is sensitive to the permeability of a sand? 20.What are the environmental corrections that are applied to SP logs? 21.What are the interpretation corrections that one needs to apply to SP logs? 22.Explain the procedure used to calculate the electrical resistivity of connate water. 23.What petrophysical information (either qualitative or quantitative) does the SP log provide in addition to that provided by a natural gamma ray log? 24. Using simple physics arguments, explain why the electrical resistivity of a rock is related to porosity. 25. Is the electrical resistivity of a rock controlled by its solid or fluid component, or by both? 26. List four independent petrophysical/measurement conditions that will cause Archies first law to fail. 27. The porosity variable used in Archies equations, is it total or effective porosity? 28. Why is it often said that Archies second law is not scientifically sound? 29. Why is the electrical conductivity of clays in contact with water relatively high? 30. When does presence of clay/shale in a rock will cause Archies first law to breakdown? 31. Explain why the wettability of a rock could have a sizable influence on the rocks electrical conductivity. 32. Explain why the uncertainty in the estimation of water saturation from electrical resistivity measurements is much higher at low than at high values of porosity. 33.Describe how the tortuosity coefficient, and the cementation and saturation exponents are estimated in the laboratory from rock core samples. Is there a potential problem in estimating these parameters when the rock core samples do not exhibit a wide range of porosity values? Explain your answer. 34.Give four petrophysical/measurement conditions that will cause Archies second law to fail. 35.Define formation factor and resistivity index. 36.List four methods, in order or their reliability, that are used in practice to calculate the electrical resistivity of connate water. 37.What types of carbonate rocks will not abide by Archies resistivity-saturation equations? 38.How do petrophysicists usually correct Archies equations in order to calculate water saturation in carbonate formations? 39.How would you integrate gamma-ray, SP, and deep electrical resistivity measurements to estimate water saturation? 40.Unaccounted presence of clay in a rock, will it cause an underestimation or an overestimation of in-place hydrocarbon reserves? Is this effect more pronounced in low-porosity rocks? Is this effect more pronounced in rocks that are almost completely saturated with hydrocarbons? Is this effect more pronounced when the connate water is fresh? 41. What is the advantages of laterologs to conventional electric logging [2] What are the differences (electrode configurations, principle, and features) of LL3, LL7 and DLL? [3] Try to derive the expression for calculating geometric factor of DLL7. [4] What are features of micrologs? [5] What is DLL-MSFL tool best used for? [6] How can apparent resistivity curves of DLL be used to identify oil/gas bearing formation? Why? [7] How does the DLL apparent resistivity curves respond to fractures?