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Subsurface Geologic Methods 

 Types of Drilling-Time Recorders 



There are three types of penetration recorders now available to the 

 drilling industry. 



The first of tiiese to be developed is known as the "Geolograph" 

 (fig. 222) . Used experimentally in 1937, it was not made available to 

 the trade generally until 1943. This device is actuated by a cable which, 

 made fast to the rotary hose swivel coupling, passes over a pulley at the 



Figure 226. "Log-0-Graf" recording unit. 



crown, down through the recorder, and up in the derrick through a second 

 pulley to a weight movable on a guideline (fig. 223). 



As the bit moves downward, the cable passes through the recorder, 

 where each foot is individually checked off on a time chart. This chart 

 is divided into minute, five-minute, and hour periods. The recorder is 

 designed to give one-foot, two-foot, and ten-foot increments of drilling 

 time. As time is constant in this method of logging, any variation in 

 the rate of penetration is indicated by a change in the spacing of the 

 foot marks on the chart. Logged in this manner, a great amount of detail 

 is made available at the time such information is most needed by those 



