224 DEEP BOREHOLE SURVEYS AND PROBLEMS 



of the fluid. Lag and oscillation of the bubble have also 

 to be provided against while temperature effects are com- 

 pensated by expansion coils. 



For operation with a wire line a line meter is applied 

 to the derrick reel starting from zero, and a watch syn- 

 chronized with the gyroscope watch is used for making 

 time readings every 25 or 50 ft., according to the depth 

 of the hole. Thus the depths are easily obtained. The 

 apparatus is run at a fairly constant speed of 150 to 180 ft. 

 per minute in cased holes, thus taking about 1 hr. for a 

 5,000 ft. hole, but this speed does not apply equally to open 

 holes. A closed traverse is got by taking readings running 

 into and out of the hole and this provides the check survey. 



The whole apparatus is entirely automatic and the obser- 

 vations are taken at predetermined intervals of time. 

 Regardless of tilt or case spin, these records yield the direc- 

 tion and inclination of the north pointer of the gyroscope 

 and its amount from the bubble. The stability of the 

 gyroscope and the sharp responsiveness of the bubble 

 permit of this even at the above rapid lowering speeds. 

 These and the times are recorded all together, as seen in 

 Fig. 6, during the continuous running of the apparatus 

 and herein will be noted the great time saving over previous 

 types of apparatus described. 



After dissembling the clinograph at bank the film is 

 removed and developed, as in Fig. 6, whence we get the 

 dip, orientation and time or depth. Applying now correc- 

 tion factors for cardinal errors, parallax and refraction 

 (which are established for each instrument) the survey is 

 plotted in one vertical section and two horizontal ones, 

 respectively, north-south and east-west and a model 

 constructed if needed. 



The makers claim for their apparatus independence of 

 magnetic and torsional influences, great saving of time, 

 easy manipulation and interpretation of records, rapid 

 mapping, great accuracy and simplicity in handling either 

 on drill stem or a line, large dip range and automatic 

 action. 



