384 ILLINOIS STATE ACADEMY OF SCIENCE 



By using percentages from the past results of ex- 

 ploration, we can estimate very roughly the amount of 

 new local accumulations of oil that future exploration 

 may be expected to find. 



In completing the thorough testing of the structures 

 now defined and partially tested Ave may expect the 

 equivalent of finding five new local producing structures. 



In the remainder of the area of best possibilities where 

 regional structure and the number of sand chances are 

 similar to the areas that have been mapped in detail we 

 may expect to find further structures in proportion to 

 areal extent as already obtained in the studied areas 

 as follows : 



(a) In areas where large scale mapping has already 

 been done we may expect the equivalent of 24 further 

 smaller structures of which about 12 may be expected to 

 be productive. 



(b) In areas as yet altogether unmapped we may 

 expect relatively the equivalent of about 29 local struc- 

 tures, of which about 8 may be the proportion of those 

 found productive. 



CONCLUSION 



To the 17 producing structures that we have today we 

 may expect to add the equivalent of five more when all 

 the structures now outlined have been tested thoroughly. 

 It is also to be expected that about 50 other local folds 

 or favorable structures may yet be found of which a pro- 

 portion of something like 20 may be expected to be pro- 

 ductive. This is slightly more than the number of pro- 

 ducing small structures that we have had up to the 

 present. 



It appears, therefore, that there are many local oil 

 accumulations capable of supplying commercial produc- 

 tion that yet await discovery in Illinois. The proper use 

 of geology, both surface and subsurface, will insure the 

 greatest efficiency in the exploration and development of 

 these resources so that the industry may continue on a 

 paying basis. Owing to the slowness with which sub- 

 surface information comes to light the development of 

 the potential reserves will extend over a number of years. 



