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THIN-SECTION 

 ANALYSIS 



Russell B. Travis 



Petroleum originates, migrates, and accumulates in rocks whose texture, 

 structure, and composition permit or prohibit formation of oil pools. They de- 

 termine which fluids will flow and the rate at which they will flow under given 

 conditions. In view of their importance, it is unfortunate that detailed study of 

 sedimentary rocks as a routine technique in surface and subsurface geology has 

 been neglected for so long. Only in recent years have oil companies begun to 

 realize that the petrographic microscope is more than a research tool and that it 

 has effective application in the increasingly difficult search for petroleum. 



Sedimentary rocks are as complex as igneous and metamorphic rocks and 

 cannot be evaluated properly without petrographic microscopic studies. By 

 using the microscope as routine procedure, oil companies are obtaining more ac- 

 curate and meaningful information from exploration programs. The newest ad- 

 vance in sedimentary petrography is in subsurface petroleum geology, in which 

 it not only aids well-to-well correlation, but can be used in planning exploration- 

 and exploitation-drilling procedures. The purpose of this paper is to point out 

 some methods that can be applied in this field. These methods fall into five gen- 

 eral areas: (1) correlation, (2) lithofacies studies, (3) reservoir studies, (4) 

 petrofabric studies, and (5) basement studies. Conventional thin sections, thin 

 sections of well cuttings, and immersion oils can be used. The comments in- 



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