down in the reservoir, as one does in a mine, all conclusions must be based on 

 inference, comparison, and experience. 



Although an understanding of the fundamentals of production engineering 

 is needed, it serves only as a background. The geologist who is familiar with all 

 of the producing structures in the trend and who knows the geologic section in 

 the wildcats is best equipped to analyze the production data from any one field. 

 There is much more to outguessing Mother Nature than being able to reduce well 

 performance to exact figures, or to analyze an electric log into precise millivolts 

 and ohms. 



Geology, being a study of the earth itself, involves its students in a con- 

 sideration of the source of sediments, conditions of deposition, up- and down- 

 dip facies changes, lateral variations in thickness or character of reservoir rocks, 

 and countless other kindred problems of sedimentology. Because of his training 

 in these matters and his continued interest in them, the well-grounded subsurface 

 geologist makes the most reliable evaluator. 



Reprinted from Subsurface Geologic Methods, 1951, p. 792-809. 



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