Il6 NOETLING: PETROLEUM IN BURMA. 



about 75 per cent, of the total yield is derived from the third oil sand 

 and if this bed shows signs of exhaustion, the end of the Yenangyoung 

 oil production will not be far off. We will have therefore chiefly 

 to investigate whether such signs are noticeable or not. For this 

 purpose it will be convenient to divide the oilfield into two parts 

 according to the method by which it is exploited, because, as we will 

 presently see, other factors besides exhaustion tend to shorten 

 the life of at least a certain portion of the oilfield. The two parts 

 are the Twingon and Berne reserve forming the northerly and 

 southerly part of the oilfield chiefly exploited by the natives, and 

 Kodoung, the central part exploited by deep wells. 



A. — The native reserves (Twingon and Berne tracts). With 

 the exception of the drilled wells inside the lots, which are the pro- 

 perty of the Government, these two tracts are at present exclusive- 

 ly worked by pit wells. As stated in the economic section, the 

 method of extracting oil by pit wells is restricted by the depth to 

 which the labourer digging the well can safely go without resorting 

 to artificial ventilation. This limit can be fixed at 320 feet depth at 

 most. When, therefore, all wells which can possibly be constructed 

 within the boundaries of the native reserves have reached that depth 

 the production must come to a standstill unless the method of drilling 

 is resorted to. A decrease in the production of the pit wells need 

 therefore, by no means, indicate the near exhaustion of the area 

 exploited by these wells, it only proves that the beds capable of being 

 reached by pit wells, that is to say, the first, second and part of the 

 third oil sand are exhausted. The deeper part of the latter may still 

 contain a considerable quantity of oil, inaccessible, however, by 

 the native method of exploitation. 



We will have therefore to answer the question, does the depth 

 of the present productive wells in any way reach the above limit? 

 As will be seen later on there are at present 519 productive wells ; 

 out of which there are about 107 which have been constructed 

 since the close of 1893, and there remain therefore 412 wells, or ap- 

 proximately 80 per cent, which were in existence previous to 1893 ; 

 ( 162 ) 



