CLINTON SAND AS SOURCE OF OIL IN OHIO 737 



oil. Relation of these areas to rock structure. Character of the oil. Prob- 

 able extensions of the producing territory. 



Discussion 



Dr. F. G. Cla"pp: In reference to the probability of the so-called Clinton 

 sand being Medina in age. I wish to mention a well recently drilled in extreme 

 northwestern Pennsylvania which found gas in what seems- to be the same 

 formation and in the Medina sand which is productive in western New York. 

 I also wish to ask Mr. Bownocker whether the oil at Butler, Ohio, had similar 

 structural relations to other oil pools in the Clinton sand. 



Reply by Dr. Bownocker: Yes, so far as I have been able to determine. 



GEOLOGICAL RELATIONS OF OIL POOLS SITUATED IN REGIONS OF MONO- 



CLINAL STRUCTURE 



BY FREDERICK G. CLAPP 



(Abstract) 



Particular reference was made to the oil pools of southeastern Ohio, which 

 may nearly all be classified as situated on monoclinal structures. Geologists 

 and oil men have generally assumed that geological structure was of little 

 assistance in predicting the positions of pools of this class. The main object 

 of this paper is to show that geology is of great value in this, as in other 

 classes of oil fields, and that good predictions may be made. The detailed 

 structures of several well known oil pools are given as examples. It has been 

 discovered that in the great majority of cases the oil has accumulated at posi- 

 tions where the change in rate of dip is locally pronounced, and that the size 

 and productivity of the pools is commonly proportional to the abnormality of 

 the generally uniform dip. The positions of accumulation are also influenced 

 by structural "ravines" crossing the sand. Although the structure of the sand 

 may be quite different from that of the surface formations, it can, neverthe- 

 less, be calculated to a considerable degree of accurac^^ from the surface, by 

 taking into account the change in intervals, which is comparatively uniform 

 for a given locality. 



Discussion 



Mr. C. W. Washburne: Stratigraphic structure is the essential element In 

 the study of most oil fields, and the proposed classification is useful because 

 of tlie aid it gives in impressing the main structural relations on the mind of 

 a student. The true facts are thus presented regardless of theory. However, 

 by over emphasis of stratigraphic structure, joints and fissures may be over- 

 looked. Is it not possible that geologists pay too little attention to some of 

 the prevalent opinions of drillers, such as their belief that fissures and joints 

 play an important rOIe in many fields? Where the oil occurs wholly in joints 

 and fissures, as in the Florence, Colorado, oil field, stratigraphic structure is 

 of little importance, and it is meaningless to call the field a monocline. An 

 additional heading should be provided for synclinal fields, such as the new 

 San Juan field of southeastern Utah. 



