652 M. L. FULLER APPALxVCHIAN OIL FIELD 



by the pushing of the drill to depths and sands previously unattainable. 

 The first well was only 69 feet deep, and for some years the depth aver- 

 aged but a few hundred feet. Then, as methods improved and as the 

 demand for oil became greater, the depth was progressively increased — 

 first to 1,000, then to 2,000, and finally to upward of 3,000 feet. Two 

 wells have been carried to a depth of a mile or more ; one 6,000 feet deep 

 at West Elizabeth, near Pittsburgh, and another, known as the McDonald 

 well, to a depth of 7,100 feet, in the southwestern corner of the State.^* 



With reasonable improvements in equipment and methods of drilling, 

 there should be no insurmountable difficulty in sinking wells to depths of 

 8,000 to 10,000 feet and at a cost still under that of many of the rotary 

 drilled wells of the Coastal Plain or other unsolidified or partly consoli- 

 dated materials. The determining factor will be the amount of oil con- 

 tained in the deep beds. If, from the preliminary testing, it is found to 

 be abundant, there will be no lack of wells to bring it to the surface. In 

 general, however, it is anticipated that there will be found a tendency 

 toward more gas and Jess oil at great depths. The deeper beds have less 

 water, and the oil will tend to occur in synclines rather than anticlines. 

 It should be lighter and of a better quality than the oils near the surface. 



Oil, however, will not be found beyond a certain depth, partly because 

 of the limitations placed on it by incipient metamorphism, as evidenced 

 by fixed-carbon ratios of over 65 or. 70 /where coals are present or by 

 cumulation w^here coals are absent. What this depth will be is as yet 

 unknown, but it may be as low as 5,000 or 6,000 feet even in areas remote 

 from strong folding. 



Of the deeper horizons, the so-called Clinton sand (Medina) appears 

 to be the most promising. In central Ohio it yields gas freely in a broad 

 belt along its upward tapering edge, and east of the gas belt it has afforded 

 several oil pools, but it soon reaches a depth beyond the present limit of 

 drilling. The fact that it is free from water suggests that the oil will 

 follow the synclinal rather than the anticlinal method of occurrence, in 

 which case there are fair prospects that it will be found in Pennsylvania 

 and northern West Virginia. Its depth at the southwest corner of Penn- 

 sylvania has been estimated at about 8,000 feet, bu.t for the most part it 

 should be from 8,500 to 9,000 feet from the surface. It increases in 

 thickness toward the east and may be less treacherous than in Ohio, but 

 it seems probable that the metamorphic action referred to will limit pro- 

 duction to considerably less depths. 



2* Two wells, one in Pennsylvania and one in West Vii-ginia, have been carried to 

 pqual or greater depths in 1917, 



