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CORE 

 ANALYSIS 



J. G. Crawford 



The economic production of oil or gas demands a knowledge of the three 

 factors that influence the potential, life, and productivity of the reservoir. These 

 factors are: (1) the characteristics of the reservoir rock; (2) the characteristics 

 of the subsurface fluid; and (3) the type and efficiency of the drive mechanism. 

 Core analysis, electric logs, radioactive logs, and drill-stem tests, together with 

 special studies and areal correlation, give an insight into the first factor; fluid 

 samples taken under reservoir conditions of pressure and temperature and 

 liberated under controlled laboratory procedures give subsurface fluid charac- 

 teristics; pressure history, production history, gas-oil ratios, and other field 

 tests point to the type of drive and estimate its efficiency. 



Core analysis is perhaps the most important tool in the determination of 

 reservoir rock characteristics, but it is only one of the many tools available for 

 the determination of the type of production prior to completion of the well. 

 The electric and radioactive log, the drill-stem test, the core analysis, are all 

 working tools for well completion. For many reasons, any one particular tool 

 may fail to give positive results, but it is doubtful that all three will fail in the 

 same well. 



Core analysis, in addition to being an important tool in well completions 

 and the most important tool for reservoir rock characteristics, lends itself 



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