THE PETROLEUM INDTSTRY OF CANADA 



indicates to the operator that the limit of the producing 

 field has been reached ; not that the black slate or shale 

 interferes with the oil strata, but it indicates the existence 

 of that part of the curve of the underlying dome which 

 covers the portion of the strata containing only water. 



The wells of Petrolia are sunk to a depth of 485 feet, 

 and those at Oil Springs to about 370 feet, in either case 

 penetrating the upper part of the Coniferous formation, 

 which in these localities is composed of a porous dolomitic 

 limestone filled with petroleum, underlaid with a strata of 

 water under considerable pressure which assists in forcing 

 the oil out of the pores of the rock into the bore of the 

 well whence it is pumped to the surface. 



In sinking wells to these depths, several strata of shale 

 and limestone are penetrated, some of which are friable, or 

 contain water, in which case iron tubing is introduced into 

 the drill hole and the objectionable matter excluded and 

 the work proceeded with. In every case an upper strata 

 containing oil is found in the Petrolia region, which is 

 utilized. At Oil Springs, however, an immense accumula- 

 tion of oil was found iu the overlying strata at a depth of 

 about 150 feet, but completely separated from "lower 

 vein" and connected with a water pressure sufficient to 

 raise the oil with great force to the surface, from which 

 were derived the flowing wells of 1862. 



The operation of sinking a well essentially consists in 

 the rise of a heavj^ bar of iron provided with a chisel 

 pointed extremity and attached with rods and cables to 

 power machinery, which alternately raising and dropping 

 the chisel cuts and pounds the rock into fine particles, 

 which are removed from time to time by passing a valved 

 tube to the bottom of the bore where it is filled and drawn 

 to the surface. 



A careful log or record of the wells is kept, that is a re- 

 cord of the different strata, etc., through which the drill 



