614 



Subsurface Geologic Methods 



where the formations are abrasive and hard enough, coring is sometimes 

 more economical than drilling; (2) the usually longer bit life; (3) the 

 possibility of cutting up to ninety feet of core at one run; and (4) the 

 high percentage of recovery. Disadvantages of diamond coring include 

 (1) the high initial expense for the barrel and bits, (2) the requirement 

 of proper operating conditions, (3) the necessity for strict supervision by 

 a person who specializes in diamond-coring operations, and (4) the gen- 

 erally higher costs than in other types of coring. 



WIRE LINt 



SPEARHEAD PULSAR 



DOG SPRING WITH PIN 

 BODY ONLY 



PULL BAR PIN 



DRIVING DOG W, 



BOLT 'f 



SLEEVE Jj 



BOLT AND WASHER— lil 



SLIP JOINT £J- 



KEY 4 REOUI RED 



BODY ONLY 



VALVE BALL Wl TH 



SEAT AND SPRING 



VALVE RETAINER 



UPPER CORE BARREL 



DRILL COLLAR 



UPPER BARREL 



REPLACEABLE END 



LOWER CORE BARREL 



DRILLING Bl T 



Bl T SLUSH RING 



SPACER SLEEVE 



CORE CATCHER 



CUTTER HEAD 



Figure 318. Wire-line rotary core barrel and other subsurface equipment. 



