LUMINESCENCE LOGGING 



319 



allowed for; the value of / obtained from measurements must be multiplied 

 by the absorption coefficient K. 



The coefficients K of the filters were determined by comparison of four 

 petroleum samples with the results of direct luminescence measurements 

 conducted in the spectral laboratory of the All-Union Scientific Research 

 Institute for Petroleum and Geological Survey under the direction of A. A. 

 Il'ina. 



In testing the apparatus described above, the following data were ob- 

 tained : 



(a) a threshold sensitivity of the order 1.3 xlO"-'^*' lumen; 



(b) a mean error of 2.5 per cent in ten measurements, the greatest being 

 8 per cent; 



(c) radiation intensity, as determined by the apparatus, proportional to 

 the actual intensity of the luminescent radiation. 



The last of these Avas established by comparing the readings of the instru- 

 ment with the resvdts of luminescent radiation intensity determinations 

 made in the laboratory with a visual photometer (see Table). 



Petroleum samples 



Relative intensity of green light, foimd on 

 instrument 



Intensity of green light, found with visual 

 photometer 



0.31 0.78 1.04 1.2 1.82 2.6 

 0.9 3.0 4.3 5.3 8.0 11.5 



Luminescence of Petroleum and Drilling Fluids. 



Presented below are the results of an investigation of the luminescence 

 from petroleum, solutions of petroleum in chloroform, and drilling fluid 

 containing petroleum, using the apparatus described above. 



Figure 3 gives the results of measurements of the luminescent emission 

 from samples of various petroleums. 



It can be seen that the lower the specific gravity of the petroleum, and 

 consequently the higher the gum content, the greater is the intensity of the 

 luminescence. With an increase in specific gravity and reduction in gum 

 content, the maximum of the luminescence spectrum is displaced towards 

 longer wavelengths, i. e. towards the yellow region of the spectrum. These 

 regularities are well known from the practice of luminescense — bitumino- 

 logical analysis of petroleum. 



