GAS, NATURAL. 



287 



gas wells were drilled in searching for oil. The 

 value of the gas was not at first realized, and vast 



to the diameter desired for the well. The drill 

 stem is given an up-and-down motion by attaching 



is introduced as soon as the Niagara limestone is 

 reached. This pipe keeps the well free from sand 

 and gravel and prevents caving. Its lower end 

 enters the Niagara limestone a few inches. A 

 smaller bit is now attached to the drill stem, which 

 drills the well of such size that a 5|-inch pipe will 



quantities were permitted to waste by blowing out the rope to one end of a horizontal walking beam, 

 into the atmosphere. But gradually it was learned which is set in motion by a steam engine some dis- 

 that it possessed high economic value as a heating tance from the derrick. The first portion of the 

 agent, and, after some difficulty, crude appliances well is usually about 9 inches in diameter, so 

 were devised for utilizing it. Natural gas was that it will readily admit an 8-inch pipe, which 

 found in Ohio at Findlay in 1885 and was utilized 

 to a considerable extent within a year after its dis- 

 covery, owing to the fact that means of handling 

 and controlling it could be obtained readily. Vast 

 quantities were wasted, however, by allowing many 

 of the wells to burn uselessly in the air. It has 

 been estimated from reliable data that millions 

 of dollars' worth of gas were wasted in this 

 manner from the Findlay fields alone, saying 

 nothing of the waste at other points in Ohio. 



The Ohio and Indiana fields are practically 

 the same so far as geological formations are 

 concerned, but differ from each other in rock 

 pressure, which fact shows them to be distinct 

 as to rock reservoir. The general surface of 

 the earth in Ohio and Indiana under which the 

 gas is found is nearly level or gently undulat- 

 ing. In most portions of the Western gas fields 

 the rock is covered with soil, though in some 

 instances it comes directly to the surface. In 

 most instances the accompanying engraving 

 will represent fairly well the formations passed 

 through by the drill. 



The gas is found in the Trenton limestone. 

 The soil above the Niagara limestone is usually 

 soft loam or clay, though immediately between 

 it and the Niagara limestone there is common- 

 ly a layer of sand or gravel. The Niagara 

 formation is a hard grayish or yellowish lime- 

 stone, which is traversed by numerous horizon- 

 tal seams containing water. The Hudson river 

 shale, immediately beneath it, is soft and com- 

 pact in texture and contains no water. The 

 line of demarcation between these strata is not 

 distinct, but the lower portion of the limestone 

 becomes more and more shaly, until it finally 

 merges into the Hudson shale. Beneath the 

 Hudson shale is the Utica or black shale, but 

 the line of demarcation between it and the 

 overlying Hudson is not usually distinct. 

 When Trenton limestone is reached the line 

 of demarcation is perfectly clear and well de- 

 fined. The Trenton limestone is so much 

 harder than the overlying shale that it is fre- 

 quently possible to hear the first strokes of the 

 drill after it reaches the Trenton. The hard, 

 rinsing blows of the drill on this formation are 

 easily distinguished from the dull thud pro- 

 duced by the strokes in the shale. The upper 

 surface of the Trenton is hard and compact 

 and usually of a dark cinnamon-brown color. 

 About a foot beneath its surface (in good ter- 

 ritory) it becomes porous and lighter of color, 



GEOLOGICAL SECTION SHOWING LOCATION OF THE GAS SUPPLY. 



though it still remains hard. In this porous portion 

 the gas or oil is found. The porous or gas-bearing 

 Trenton usually extends from 10 to 20 feet in depth, 

 but in some instances as much as 60 feet. 



When it is desired to drill a gas well, a derrick 

 about 74 feet in height is erected, and to one 

 side of it, at its base, is attached a large wind- 

 lass, around which is coiled a rope a little more than 

 2 inches in diameter and from 1,000 to 2,000 feet 

 long. This rope extends to the top of the derrick, 

 where it passes over a pulley and thence down- 

 ward to the center of the derrick, where it is 

 attached to the drill stem, which is a heavy cylin- 

 drical steel bar about 4 inches in diameter and 

 sometimes nearly 30 feet long. To the lower end 

 of the drill stem is screwed the " bit," which is 



readily enter. As soon as the Hudson shale is reached 

 and the driller feels sure that all water is passed, the 

 5f pipe or ' casing " is introduced. This pipe shuts 

 all water out of the well, and another bit is attached 

 to the drill stem, which will readily pass through 

 the interior of the casing. The drilling now pro- 

 ceeds until Trenton limestone is reached, the drill- 

 ings being removed from time to time by means of 

 a " bailer." 



Soon after the drill reaches the Trenton rock the 

 gas begins to flow, and if the well proves to be 

 large the flow increases until the roar of the escap- 

 ing gas through the casing can be heard a long 

 distance. As soon as the well is completed it is 

 ready for the " packer." This is a hollow cylinder 

 of rubber which nearly fits the well and is usually 



made of tool steel and is widened at its lower end set just above the surface of the Trenton limestone. 



