LUMINESCENCE LOGGING 



325 



of the petroleum. However, it is difficult to distinguish on spectral character- 

 istics between the explored petroleum, containing a large quantity of light 

 fractions or lubricating oil components, and petroleum products which have 

 entered the drilling fluid. 



Figure 9 shows results of luminescence analysis of drilling fluid sample:^ 

 taken while drilling one of the wells of the Aleksandrov area (Bashkiria). 



05 



440 



600 



Fig. 



520 

 9. Luminescence spectra. 1 and 2 — drilling fluid with addition of graphite 



grease; 3 — drilling fluid with petroleum; 4 — oil-bearing sandstone; 5 — drilling fluid. 



Samples of fluid, taken while drilhng an interval of 1600-1730 m, give fairly 

 intense luminescence; the spectral characteristics 1 and 2 have a maximum 

 about 480 m/ii, i.e. at the same place as for lubricating materials. This indi- 

 cates that the luminescence of the given samples of drilling fluid is due to 

 lubricating materials which have fallen in. The spectral characteristic of 

 drilling fluid sample taken at a depth of drilling greater than 1750 m has 

 a maximvim in the region of 540 nijLi, ^vhich corresponds to the maximum 

 in the spectral characteristic of petroleum in the bed. This indicates the 

 discovery of a petroleum-bearing bed. A core sample taken from this depth 

 proved to be oil-bearing sandstone. The spectral characteristic of this sand- 

 stone is the same as that of the drilling fluid, sampled during the drilling 

 of this interval. 



