326 



T. V. Shcherbakova 



VIEWING WINDOW 



To provide for continuous observation of the luminescence of the drilUng 

 fluid coming from the well, the apparatus must be equipped with a viewing 

 window immersed in the drilling fluid. To avoid distortion of the results 

 of the observations it is essential that the petroleum from the drilling 

 fluid should not stick to the viewing window and remain on it. Thus, the 

 surface of the viemng window must be hydrophylic. 



Trials of various materials showed that it is best to use glass* with a de- 

 greased surface for the viewing window. The drilling fluid easily washes oil 

 drops from the surface, and the petroleum does not leave traces on it. This 

 was checked by the following method. 



The usual clay suspension ^vas poured into a narrow bath 1 m long; in one 

 part this "was replaced by a fluid containing petroleum, the boundary between 

 the ordinary clay suspension and the clay suspension containing petroleum 

 being made as sharp as possible. Observations were conducted with the 

 aid of an optical arrangement containing a suorce of ultra-violet light and 

 a photoelement ; optical contact with the clay suspension was achieved by 

 means of a window, covered in one case by glass and in another by Plexiglas, 



iQO 



90 



80 



70 



< 60 



50 



^ 40 



30 



20 



10 



O 



I , 



25 



100 L, cm 



Fig. 10. Record of the luminescence intensity when glass is moved through drilling 

 fluid. 1 — drilling fluid; 2 — drilling fluid with petroleum. I — measurement with de- 

 greased glass; II — measurement with organic glass. 



* The glass partially absorhs ultra-violet rays, and this leads to a reduction in the sensitivity 

 of the apparatus. However, this does not create any fundamental difficulty in the operation 

 of the apparatus. 



