32 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Burbach Works, Beendorf, Germany, contains a manom- 

 eter c with a bent measuring tube d (Fig. 11). The fluid 

 enters through holes a from the borehole and holes h to 

 the measuring chamber and gaging tube. The manometer 

 is provided with an indicator which fixes the highest pres- 

 sure. The measurements are very simple; the rods and 



Fig. 11. — Horizontal borehole pressure recorder. (Burbach.) 



gage are pushed into the hole to the spot to be measured, 

 the hole being full of rinsing water. Then on pulling 

 the gage out and reading the highest pressure thereon the 

 deviation from the horizontal can be calculated by consider- 

 ing the specific gravity of the rinsing fluid. This latter, 

 of course, is essential since water is not the only fluid; in 

 potash mines magnesium chloride liquor is used. 



Borehole set horizontal 



Atmospheres 

 of Pressure 



Fig. 11a.- — Horizontal borehole profile. 



Figure 11a illustrates this simple principle, being an 

 actual example from a German potash mine where a fluid 

 of 1.275 sp. gr. is being employed. To get the ordinate 

 at the length 340 m., where the gage has registered 2.5 

 atm. of pressure fall, proceed thus: 



10 X 2.5 



1.275 



= 19.60 m. 



and similarly for the length 500 m. registering 4 atm. fall: 



10 X 4 _^ __ 

 -3^275-= 31.36 m. 



h. When the borehole deviates upward, the pressure is 

 read at each desired spot by sending in the gage on the rods 



