70 NOETLING : PETROLEUM IN BURMA. 



To me it seems obvious that there exists a connection between the 

 height of the river level and the quantity of the production of the 

 native wells, and, as 1 have already pointed out, that there is a 

 relation between the activity of the mud volcanoes and the height of 

 the river (see page 44), it is not unreasonable to suppose that the 

 same influence which stirs up the mud wells affects the petroli- 

 ferous sands in such a way that the discharge of the oil is more 

 abundant during the rainy season than during the other months. The 

 production of the drilled wells exhibits the same phenomenon, al- 

 though it is here not so conspicuous for reasons which are easily 

 explained. In the pit wells the oil slowly filters into the well, there 

 to gather, while it is pumped out in a permanent stream from the 

 drilled wells. Probably, therefore, the quantity obtained from the 

 latter does not represent the quantity which would be obtained if the 

 oil were allowed to collect slowly in the bore hole, as in the pit wells. 

 The explanation of this strange phenomenon is by no means easy 

 because we know unfortunately little or nothing with regard to the 

 movements of liquids in rocks at considerable depths, and under con- 

 siderable pressure. We may, however, at once dismiss the theory of 

 the influence of the temperature ; quite apart from the fact that 

 the temperature is usually highest when the production is 

 lowest (February to April), it is almost certain that the beds 

 which supply the oil are beyond the yearly range of the changes 

 of temperature on the surface. 



But perhaps the following theory will afford an explanation. It 

 seems very probable that the petroliferous series is intercalated in an 

 arenaceous formation of considerable thickness, permeated by water. 

 We further know that the chief oil producer, the fourth oil sand, is 

 found at a depth which differs not materially from the high water level 

 of the river. I believe we may safely assume that when, during the 

 rains, the river rises to sometimes fifty and more feet above its low 

 water level, the ground water will also rise, and this in its turn 

 presses on the petroliferous sands and forces the oil to ficw more 

 fieely. 



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