YENANGYOUNG. 75 



whether a certain higher bed, which was dry at the time when it was 

 drilled through, contains water during other seasons of the year. 



The second feature is more easily explained ; we may well 

 imagine that, with the gradual removal of the oil from the petroli- 

 ferous sands, the water gradually rose under the hydrostatic pressure 

 and replaced the oil. As the two wells above mentioned have been 

 drilled near the margin of petroliferous tract, such a supposition is 

 by no means improbable. 



As the last feature in the occurrence of oil, we have to deal with 

 flowing wells and the presence of gas. That gas emanates from the 

 petroleum can be easily seen in the wells, in some of which the 

 evaporation of gas is so rapid that the surface of the pool of oil 

 gathered in the well is in an agitated state, as if boiling, and gas 

 bubbles are incessantly rising. No gas pressure worth speaking of 

 has been observed in any of the drilled wells, although there is 

 unquestionably a small pressure, but insufficient to produce flowing 

 wells. With regard to this the Yenangyoung oil field has not proved 

 a success, and all the oil must be pumped from the wells; as far 

 as our present experience goes it is also very unlikely that 

 flowing wells will be found within the limits of the Yenangyoung oil 

 tract. 



In conclusion a few words must be said about the curious occur- 

 rence of gas recorded in wells Nos. V, VI and VII just at the southern 

 limit of the Berne oil tract. In No. V two consecutive beds contain- 

 ing gas were found, the upper between 91 and 205 feet from the 

 surface, the lower at 286 to 330 feet ; in No. VI the gas vein was 

 struck at 255 feet, and in No. VII at 355 feet from the surface. The 

 presence of gas just at this part of the oil tract, that is to say, its 

 southern limit, is not easy to explain, particularly if we recollect that 

 the gas is found here at a lower level than the oil in the other 

 parts, unless we assume that the sand containing gas represents the 

 fifth oil sand of the other deep wells. The only manner by which 

 the presence of gas at this part of the oil field could be accounted 



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