374 ILLINOIS STATE ACADEMY OF SCIENCE 



ably barren areas may be discarded and the oil well tests 

 for new production be confined to the small areas of 

 greater promise. Although the element of chance is 

 more or less still present in drilling these promising 

 areas, "wildcatting", as it is called, can only thus be 

 brought within the bounds of good business judgment. 



The annual decline of production has not been so rapid 

 as the natural exhaustion of the older wells. New pro- 

 duction has been obtained from time to time through 

 proper development and prospecting. Outside the old 

 fields new small pools have been discovered and de- 

 veloped. Within the old fields drilling of both inside and 

 edge wells has still brought in some additional produc- 

 tion. Deepening existing or exhausted wells has resulted 

 in some cases in finding other producing sands. Im- 

 proved methods of recovery such as the use of the 

 vacuum pump and in some cases the practice of return- 

 ing compressed gas or air to the sands have helped also to 

 keep up production. 



It is not expected that there will be discovered in Illi- 

 nois any further oil fields of sufficient magnitude to raise 

 the total production above the present figure, but it is 

 reasonable to expect, as will be seen later, that new pro- 

 duction will be obtained from time to time which will in 

 a great measure offset the decline due to the exhaustion 

 of the older wells, many of which are now approaching 

 the limit of economic life. It will be shown that the find- 

 ing of further accumulations and the obtaining of higher 

 yields from existing wells or fields can best be brought 

 about by the proper use of geology. 



The results of the drilling done during 1922 show that 

 in the older fields of the southeast 118 holes were drilled, 

 of which 36 were dry and 82 were producing wells with 

 a total reported flush production of 1300 barrels per day. 

 These include a few rank wildcats which unfortunately 

 are located often without the basis of reliable judgment. 

 But the majority were drilled in development of inside 

 acreage of light production and to determine the edge 

 limits of the main producing fields. In the rest of the 

 State 223 holes were drilled, of which 53 were dry, while 

 170 were wells with a reported flush production of 4,590 



