Subsurface Logging Methods 



485 



on the chart the time drilling ceased. When drilling is resumed, the pen 

 returns to its normal drilling position. 



The operations record shows to the minute how much time is con- 

 sumed in making trips, connections, repairs, straight-hole tests, and like 

 operations. This record not only aids the contractor in spotting the 

 equipment requiring repairs that are becoming so costly that replace- 



FiGURE 229. Martin-Decker recorder 

 showing fluid reservoir, hose, and 

 recording gauge with chart. 



ment would be profitable, but also is being used in the development and 

 testing of new drilling techniques and equipment. 



A number of mud-logging companies have included "Geolograph" 

 units in their logging equipment. 



As the accuracy of mud logging is dependent on the ability to cor- 

 relate the shows of oil and gas with the source beds, it is important that 

 enough detail be obtained from the time log to enable the operator defin- 

 itely to check the show in the mud stream back to its point of origin. 



