PROBLEMS OF GAS LOGGING ESTIMATION 



3B 



Fig. 3. Results of gas logging by means of DP and PG degasifiers (total content of 

 hydrocarbon gases is given). 



Case i— Fig, 3 shows the results of gas logging with DP and PG degasi- 

 fiers against productive Devonian beds in one of the wells. 



According to the curve of total gas content, obtained with the PG degasi- 

 fier, the whole interval is characterized by low gas indications (background 

 values). When using the DP gasifier, the bed D^ is marked by readings of 

 100-450 iiA, which corresponds to a drilhng fluid content of 2.6-13.5 cm^/1. 

 The gas factor for this case is 3-15 m^/m^. According to available data the 

 gas factor of the bed Dj^, when it is oil-bearing, is equal to 35^5 m^/ra^, 

 and consequently, in the given case the bed can be described as water- 

 bearing, containing residual petroleum. 



The bed D^ on the gas log obtained with the DP degasifier is shown by 

 individual peaks, in quite good agreement with the mechanical log and the 

 deviations of the curve PS. Even the thin layers, separated by sections of 

 clay, are distinguished. 



Case 2 {Fig. 4)— A well was developed in the Tournaisian deposits. On the 

 total gas content curve, obtained when using the DP degasifier, a series of 

 intervals with a high content of combustibles can be detected. At the same 

 time on the corresponding curve obtained by using the floating PG degasi- 

 fier, only small increases are shown against these intervals. The whole 

 curve is very smooth. 



