NUMBER OF WELLS. 179 



B.—Froyt 1888 to the beginning of i8g$. When I first 

 examined the Yenangyoung oilfield in 1888 no map of this area 

 was in existence, in fact we may say that this tract was almost 

 a terra incognita. To arrive under such circumstances at a fairly 

 correct idea regarding the number of wells, proved a difficult 

 task. I was obliged to prepare a map first, which was done by pacing 

 and measuring the angles with the compass and to enter on this map 

 the position of the wells. To increase the difficulties under which 

 my work was carried out was the unsettled state of the country. I 

 may thef efore have overlooked some wells, but on the whole I think 

 thte number given is fairly Correct. 



During the year 1890-91 a thorough survey of the Yenangyoung 

 oilfield was undertaken, during which the greatest care was taken 

 to ascertain the number of wells in existence, and the locations of 

 those which had been abandoned and were eventually filled up. The 

 wells were carefully numbered and their positions accurately fixed. 



Generally we may divide the wells into two classes, productive 

 and unproductive, and although the former are those of economic 

 value, the study of the latter is not without interest, inasmuch as 

 it reveals some features of the evolution the petroliferous tract has 

 taken. 



The productive wells require no further definition, but a short 

 explanation is necessary as to what I regard as unproductive wells. 

 The foremost among the latter class are of course such wells as 

 once yielded petroleum, the supply of which has run so short 

 that they have been abandoned. By want of care the casing broke 

 down and the walls sliding, eventually funnel shaped holes were 

 formed, which in many cases have been entirely filled up again. The 

 second in importance are wells under construction, viz, } wells which 

 have not reached the petroliferous sand, but which are energetically 

 deepened. Such wells are apt to become a most important factor 

 in the future, although not productive at the time. 



The third class are well sites, i.e, f places which have been 

 selected for the future location of a well. The owner of su»h a well 

 N 2 ( 225 ) 



