Subsurface Laboratory Methods 343 



39. How is kaolinite distinguished from montmorillonite by use of stains? 



40. What is the importance of knowing whether a montmorillonite clay 

 or kaolinite clay is involved in construction problems? 



41. What factors control the shape of sedimentary grains and fragments? 



42. What is the relationship between porosity, grain size and perme- 

 ability? 



43. What magnifications are involved in electron-microscope studies? 



44. What are the possible uses of the electron microscope in correlation 

 work? 



45. Is there any relationship between subsurface lithologic units and their 

 water characteristics? 



46. How are ground waters classified? 



47. Study the graphic method of representing ground-water data in figure 

 120. 



48. Compare the composition of Lower Cretaceous waters of the Rocky 

 Mountain Region given on table 11. 



49. What are the advantages and limitations of the X-ray diffraction 

 analysis? 



50. How is the sample prepared for an X-ray mineral determination? 



51. Study the X-ray pattern given on plates 7 and 8. 



52. How may X-ray data be applied to stratigraphic investigations? 



53. What is the purpose of core analysis? 



54. What information is given on a core-log? 



55. How should one sample a core from which a detailed analysis is to 

 be made? 



56. What factors control the amount of residual oil in a core sample? 



57. What is meant by "connate water" and what methods are applied for 

 calculating the connate-water saturation of sand formations? 



58. How are core data used for interpreting probable production? 



59. What physical characteristics are associated with permeable, high- 

 pressure gas sands? 



60. What is meant by "bleeding cores"? 



61. What are the applications of core analysis? 



62. What is the general principle and procedure of differential-thermal 

 analysis? Could such a technique be applied to certain stratigraphic 

 problems? How? 



63. What rock types are best suited for differential thermal studies? 



64. What is the value of shale-density data? 



