PROBLEMS OF GAS LOGGING ESTIMATION 



311 



Table 



Value of gas saturation of the fluid at various rates 

 OF boring and mud-pump capacities 



values given in Table 3. This is evidently explained by the driving of the 

 gas back into the bed during the process of drilling. 



With a knowledge of the gas factor of the productive beds, it is possible 

 to form a preliminary idea of the possibility of detecting them by gas logging 

 under the drilling conditions that are used in boring productive beds. 



As folloAvs from Tables 2 and 3, for some regions of Bashkiria the gas 

 saturation of the drilling fluid in exploring the productive deposits will often 

 be less than 16 cm^/1. This is below the sensitivity possessed by a gas- 

 logging station with a floating PG degasifier. As a result of this, a whole 

 series of productive beds is not indicated on the gas logs. 



In order to record productive beds in the Bashkirian regions, the sensi- 

 tivity of the apparatus employed must be increased between seven and ten 

 times. This can be done by increasing the degree of degasification of the 

 drilling fluid. In this connection the DP* degasifier, with a higher degree 

 of degasification than the floating degasifier, was developed and tested. 



The DP degasifier consists of a metal cylinder, inside which is fixed 

 a hollow drum together with a wire brush. The drum is rotated by means 

 of an electric motor fixed above the degasifier. The latter is placed in the 



* The degasifier was put forward by B. V. Vladimirov and L. A. Calkin (inventor's 

 certificate No. 90747 of 28 June 1950). 



