YENAN'GYOUNG. u _ 



out of these 412 wells I selected 328 wells of which it could be proved 

 that they had been permanently productive since the beginning of 

 1 89 1 or during the last four years, all the others were disregarded. 

 These 32S wells, representing 65 per cent, of the total iTumber, 

 supply 64 per cent, of the total production and are therefore of 

 the greatest importance in answering this inquiry. It is obvious 

 that, if these wells begin to show signs of exhaustion, the production 

 must naturally decline, unless other means are devised to keep it up. 

 These 328 wells, all of which have been identified, had an aggre- 

 gate depth of 67,340 feet in 1891 ; that is to say, the average depth 

 of each well amounted to 205 feet. 



In 1893 these same wells had an aggregate depth of 73,471 feet, 

 or the average depth of each well had reached 224 feet from the 

 surface. 



In 1895 the depth of these wells had increased to an aggregate 

 of 74,952 feet or each well averaged 228 feet in depth. 



These figures will be more impressive if we express them in 

 percentages of the possible depth, estimated at 320 feet ; in this case 

 the average depth of each well amounted to — 



in 1891 ..... 64 per cent, of possible depth. 



a «893 7° „ „ 



>, 1895 71 „ „ 



The above figures unmistakably prove therefore that 65 per cent, 

 of the productive pit wells have reached at the beginning of 1895 

 71 per cent, of their greatest possible depth. In other words, 65 

 per cent, of the existing productive wells, supplying 64 per cent. 

 of the total yield of oil, have reached such a depth, that they approach 

 very closely their maximum depth, which they would reach within 

 the next seven years certainly, unless the difficulties in reaching that 

 depth become so great that they had to be previously abandoned. 



From this point of view the outlook is a very serious one, and 

 the more so because it is based on undeniable facts, 



( 163 ) 



