570 



busch. SUBSURFACE TECHNIQUES 



[Ch. 31 



Coring time Graphic Lith 



(min.perft.) Log Type Depth Permeability (mds) Porosity (%) 



40 20 400 300 200 100 10 20 



6,485- 



Legend 



': A h 



Sand, medium to 

 coarse, angular to 

 subangular grains 

 Same, cross- 

 bedded 

 Same, pores 

 contain clay 



B 



Bu 



Sand, medium, 

 subangular to 

 rounded, small 

 irregular openings 

 Same, cross- 

 bedded 



Same,clay-filled 

 open spaces 

 Same as B 

 but without 

 openings 



C Sand, fine to 

 medium angular 



C a Same, with 

 clay in pores 



C b Same, with clay- 

 filled open spaces 



D Sand, fine, dense, 

 hard 



D a Same, cross 7 

 bedded 



Dj, Same, with 

 clay in pores 



D c Same, with 

 chert pebbles 



Fig. 5. A graphic log. This log shows cored intervals, drilling time, lithology, 

 depth, permeability, and porosity of a productive sandstone. (Courtesy of The 



Carter Oil Co.) 



