672 Subsurface Geologic Methods 



Two types of picture surveys are made: one a continuous strip photo- 

 graph of the well bore showing every inch of the formation, and the 

 other a series of single-shot pictures spaced at intervals of one foot, five 

 feet, or any other desired interval. Usually the one-foot interval is used. 

 The continuous-strip picture is made by lowering the camera only two 

 inches between exposures and then using only the center section of each 



Figure 360. Well-developed stylolitic zone that has been leached out by action of 

 subsurface fluids. Vertical striae may be due to presence of stylolites running 

 transversely to the one appearing in bottom of picture. The phenomenon of a 

 leached stylolitic zone is interesting because in some limestones these zones serve 

 as reservoirs of commercial deposits of oil (2,559 feet). 



print. The prints are fitted together to make a continuous picture of the 

 well bore in much the same manner that aerial photographs are fitted to- 

 gether to make photomaps. 



Figures 357 to 363 are examples of photographs taken in a well in 

 west Texas. The formation is the San Andreas section of the Permian lime 

 in the Hendricks pool. More than 400 pictures were taken in this well at 

 depths of from 2,300 to 2,725 feet. When the pictures were taken, the 

 well fluid was within 200 feet of the top of the well. 



