PROBLEMS OF GAS LOGGING ESTIMATION 



303 



4-0 4-5 5-0 



'■5 2-0 2-5 3-0 

 Gas readings, % 



Fig. 1. Calibration curves for determination of gas saturation of the drilling fluid from 

 readings obtained in gas logging with a floating degasifier. 



the amount of gas entering the drilhng fluid as a result of diffusion through 

 the walls of the well is very small and has no practical significance and in 

 most cases infiltration does not occur since the pressure in the bed is below 

 that of the column of drilhng fluid. 



In contradiction to this, E. M. Geller considers that gas enrichment 

 of the drilhng fluid is largely caused by infiltration of oil or gas from the 

 bed, arising as a result of a reduction of pressure in the well during rota- 

 tion of the drill bit*. According to Geller, a favourable condition for this 



* E. M. Geller. On the conditions of passage of gas and ofl into clay solution of weUs 

 during drilling. Sb. "Geokhiraicheskie metody poiskov nefti i gaza" Geochemical methods 

 of prospecting for oil and gas 2nd ed. Gostoptekhizdat, 1954. 



