PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 353 



onl, at first, 300 or 400 barrels a day, or to yield in all 20,000 barrels. — 

 They sometimes run two or three years before exhaustion. The produc- 

 tiveness (tf the Lewellya well, on the Little Kanawha, greatly exceeded 

 these figures. 



Wells Connected by Free Channels. 



Ill this class the passage from one cavity to another being free, where 

 the eciuilibrium between tliem is disturb(Kl, it is immediately restored. — 

 Sometimes in the sinking of a new well, in the neighborhood of others, a 

 fissure in the rock is met with, which carries a. flow of water from the new 

 well into the others. This evil is remedied by stopping up tigiitly the 

 space outside of the tube by lowering a bag filled with dry seed to a point 

 below where the current of water enters; as this water penetrates it, the 

 seeds swell and close up the passage. 



In the eases spoken of thus far, the quantity of gas is supposed to be 

 considerable; but in many instances it is so slight as to require the con- 

 stant use of the pump. Yet wells of this character are, t(j some (extent, 

 intermittent. As it is not usual to work these wells at night, they begin 

 each day with a new accumulation, which gives them a certain regularity 

 of daily action, often considered mysterious. There is a well a few miles from 

 Marietta which yields oil onl^^for a short time in the morning; when neglected 

 till that time has passed, it is unproductive for the dsiy. This is owing to the 

 proximity of another well whicli drains its water in the daytime, but, by 

 resting at night, allows it to bo replenished. In wells of small supply the 

 quanty of oil is not increased by extending the intervals of cessation of 

 work beyond a certain time. 



General Observations. 



Oil wells commonly vary in depth from 100 to 800 feet. The deepest are 

 as apt to raise water to the surface as the shallowest. This indicates a 

 greater compression of gases at the greater depth ; owing, doubtless, to 

 its connection with higher columns of water. The activity of some wells 

 is increased by rains; that of others, with less gas, is thus retarded. It 

 nuist not be assumed, however, that their connection with subterranean 

 currents is immediate and unobstructed. Prof Evans knows of no instance 

 where there is reason to suppose that the oil is raised to the surface by the 

 direct pressure of a stream of water, whose head is higher than the issue, 

 as the jets of the Artesian wells are said to be produced. In spouting 

 wells, the pressure of the gas, as the immediate agent, becomes known not 

 only from their variable action, but also from the actual escape of gas, and 

 consequent cessation of flow whenever tiie oil is reduced to a certain level. 

 If collections of oil had direct and free connection with strong currents of 

 water, the mechanical agency of these ciurents would bear them rapidly 

 away. As it is, minute quantities come to the surface with the springs, 

 showing a very slow process of drainage. As an index of the location of 

 oil cavities this sign is not reliable; for that which issues may have been 

 carried by the streamlets, for miles from its source. Gas springs are less 

 deceptive signs; for the gas, being more buoyant than the oil, and not 

 [Am. Inst.] W 



