ABSTRACTS 



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GEOLOGY. — The Cleveland Gas Field, Cuyahoga County, Ohio, with 

 a study of rock pressure. G. Sherburne Rogers. U. S. Geologi- 

 cal Survey Bulletin 661-A. Pp. 68, with 2 plates and 13 figures. 

 1917. 



Most of the wells in the Cleveland gas field, which, is located in the 

 westerly suburbs of the City of Cleveland, are from 2500 to 2900 feet 

 deep and draw their supplies from the so-called Clinton sand. The 

 structure of the region is, broadly speaking, monoclinal, the formations 

 outcropping in the western part of Ohio and dipping to the east be- 

 neath the great Appalachian Coal Basin. The Clinton sand itself 

 does not outcrop, however, but feathers out in the central part of the 

 state, and the Cleveland field and other important oil and gas fields to 

 the south occupy a belt along the upper or thinning edge of the sand. 

 The accumulation of the gas at Cleveland has been influenced also 

 by structural considerations, the field being roughly coincident with a 

 broad gentle bulge or nose on the monoclinal slope, and has been affect- 

 ed locally by the porosity or texture of the sand. 



Owing to the very rapid growth of the field which was started in 

 1912, and which in 1915 contributed about 40 per cent of the Ohio 

 production, the records of pressure and production decline are unusu- 

 ally complete and afford an interesting study. It appears that in any 

 large group of wells there is a fairly close average relation between 

 rock pressure and production. Hence by studying the pressure de- 

 cline in any group it is possible to predict in advance of drilling the 

 probable flow or volume of a new well in that group. If desired, the 

 estimate may be evaluated according to the theory of probability and 

 the number of chances in a hundred that the flow will not exceed a 

 given figure may be calculated. Although the actual figures cited of 

 course hold only in the Cleveland field the principles discussed should 

 be applicable in many areas. G. S. R. 



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