211 I. C. WHITE — THE MANNINGTON oil. FIELD. 



a much longer life than others not so fortunately placed, and that the immense 

 amount of capital invested in pipe lines to them will receive an adequate return 

 he fore the gas shall have been exhausted. Nothing hut time can determine the 

 life of gas territory situated upon a well developed arch, like the Murraysville or 

 Saltsburg anticlines. 



"In Washington county, Pennsylvania, there are three principal geological hori- 

 zons at which large supplies of gas are found, and, taking the Pittsburg coal as a 

 datum line, these horizons come in as follows, neglecting fractions: 



Fret. 



First horizon, below Pittsburg coal 900 



Second " " " " 1,800 



Third " " " " 2,000 



"The first horizon furnishes a gas very much like the .Murraysville gas, and the 

 pressure seldom rises above 300 pounds to the square inch. It is contained in the 

 no. XII conglomerate, since the rock lies about 200 feet above the Subcarboniferous 

 limestone. 



"The second horizon is identical with the first Venango oil sand, and seems to lie 

 the gas horizon par excellence of southwestern Pennsylvania, since it is also the great 

 producing rock in Beaver, Alleghany, Butler and Westmoreland counties. It is 

 nearly always overlain by a dark, close slate, which has evidently been a factor in 

 enabling the rock to retain the gas. The product of this rock is strongly scented 

 with petroleum in Washington county, but at .Murraysville and Grapevine, in 

 Westmoreland, it is nearly odorless, though it is oil-scented again near Latrobe. 



" This same rock is the gas reservoir at AVellsburg, West Virginia, and has there 

 been identified by Professor Orton as the Macksburg oil sand, which he in turn 

 identities with the Berea grit. 



" The third great gas horizon of Washington county is in the 'stray,' or upper- 

 most member of the third Venango oil sand. The famous Mel ruigan well is in this 

 sand, as also the Donaldson, Willison, McClean, and others in Washington county. 



"The total pressure to which the gas from this rock will rise, when shut in, has 

 never been determined, so far as I am aware, hut it would probably exceed that 

 from the first Venango, or Murraysville sand, which seldom rises above 050 pounds 

 to the square inch. 



"The explanation of uas pressure in any particular rock seems as yet unite 

 obscure, but there is evidently an increase of pressure with increase of depth, 

 though the law of increase (if there be any law) is not uniform. For instance, the 

 wells at Erie which go down 600 to 700 feet, show a maximum of only 40 to 50 

 pounds. Mr. Westinghouse, of the Philadelphia company, Pittsburg, suggests that 

 the gas pressure in any case may be due to the water, or hydrostatic pressure on 

 the rock, and this is possibly true, since it would account for the greater j^ressure 

 as the sand gets deeper below the surface." 



Since the above statements with reference to the Washington county gas horizons 

 were written the drill has developed two others, viz, one in the "Big sand," or 

 Manifold farm oil rock, which begins directly under the Mountain or no. XI lime- 

 stone, and is 250 feet thick. This rock is the upper member of the Pocono sand- 

 stone, and is called in Ohio the "salt sand." The horizon in it which furnishes gas 

 is about 1,150 feet below the Pittsburg coal. 



The other gas horizon is the so-called "50-foot rock," which has proved so prolific 

 in oil at the Smith no. 1. The top of this sand conies about 1,850 feet below the 

 Pittsburg coal, and it is very probably identical with the second Venango oil sand. 



