Occasionally in passing through the shale, small fissures in the rock are passed through, with circumstances indicating the presence of a stratum or vein of water, as at such times the sand accumulated in boring all disappears, leaving the bits clean and bright. At other times small veins or cavities of petroleum are pierced, the product of which rises to the surface of the well, and indicates its presence by appearing in the sand pump. In the earlier stages of the business this 'show of oil,' as it was termed, was considered most favorable to ultimate success; but latterly it is not regarded as essential, as many first-class wells have been discovered without the intermediate show; and on the other hand, there has been many a brilliant show that has resulted in failure and disappointment.
The presence of surface oil is not always a sure criterion in deciding upon a location for a well. Oftentimes very fine wells are opened in localities where no oil has been found on the surface, and no appearance of oil having been obtained at any previous time in the neighborhood. Perhaps the most unsuccessful operations in the whole Oil Creek valley have been in the midst of the ancient pits that have already been alluded to. Wells have been bored in the bottom of these pits without the least success. At a point near the bank of the Alleghany, some two miles above Franklin, there was a well-known oil spring some forty years ago. It supplied the family that lived near it as well as the surrounding neighborhood with petroleum for medical and other domestic purposes to the extent of their wants. For many years the supply has entirely failed. During a recent excavation, at the precise spot where it was known formerly to exist, for the purpose of laying the abutment of a bridge, no trace of oil was found—not even a discoloration of the earth.
Of course the boring of wells has become quite an institution in the oil region, and is carried on with great system. After selecting a site, the first thing in order is the erection of a derrick. This is a frame in the form of a truncated pyramid, about ten feet square at the bottom, and five at the top, having one of its four posts pierced with rounds to answer the purpose of a ladder, by means of which the workmen can ascend and descend. This derrick is from twenty to thirty feet in height, and has at its summit a pulley, by means of which the boring implements are drawn from the well. A pit is then sunk through the earth within the derrick, about six feet square, until the work is interrupted by water. The remaining distance to the rock is reached by driving strong cast-iron pipe by means of a battering ram. This pipe has a caliber of about five inches, with walls of one inch in thickness. It is prepared in joints of about eight feet in length, which are connected together at the point of contact by wrought-iron bands. When the pipe reaches the rock, the earth is removed from its cavity, and the operation of boring is ready to be commenced. Occasionally, however, this driving operation is interrupted by coming upon a huge bowlder. When this is the case, the boring operation is commenced, and a hole made through the bowlder nearly equal in size to the cavity of the pipe, when the driving is resumed, and the pipe made to ream its way through the stone. Sometimes in these operations the pipe is fractured, or turned aside from a perpendicular direction, when the place is abandoned and a new location sought for.
The boring implements do not differ materially from those used in sinking artesian wells. As a general thing, bits of two or three sizes are used, the first and smallest of which only has a cutting edge. If the hole to be sunk through the rock is to be four inches in diameter, the bits would be, first, one with a cutting edge two inches in width; secondly, a blunt bit, three inches wide by one inch in thickness; and lastly, by a similar bit four inches wide. These bits have a shank about two feet in length, that is screwed into an auger stem ten or twelve feet in length and about one inch and a half in diameter. Connected with this auger stem is an arrangement called, technically, 'jars'—two elongated loops of iron, working in each other like links in a chain, that serve to jar the bit loose when it sticks fast in the process of boring.
Sometimes this auger stem is connected with wooden rods, joined together with screws and sockets, new joints being added as the work proceeds; but more generally the connection is with a rope or cable of about one and a half inches in diameter. To this rope the auger stem is attached by a clamp and screw, that can be readily shifted as the progress of the work renders it necessary. The entire weight of these implements is from four to six hundred pounds. The power applied is sometimes that of two or three men working by means of a spring pole; but oftener a steam engine of from four to eight horse power. Midway between the well and the engine a post is planted, on which is balanced a working beam about sixteen feet in length: one end of this beam is attached to the crank of the engine, and the other to the implements in the well. The power is applied to raising the bit—the blow is produced by the fall of the same when relieved by the downward motion of the working beam.
In the process of boring, the workman is seated over the well, and, by a transverse handle attached to the machinery just above the rope, turns the rope, and with it the bit, partially around, so that each stroke of the bit on the rock beneath is slightly across the cut that has preceded it. After the fore bit has proceeded about two feet, or until the work begins to clog with sand, it is withdrawn, and the next is inserted in its place, and the work is then finished as it goes by the last bit. The fragments of rock that are cut away descend to the bottom of the well in the form of sand, and are readily withdrawn by means of the sand pump. This is a simple copper tube about six feet in length, with a diameter something less than that of the well, and furnished at the lower end with a simple valve opening upward. This pump is let down into the well by a rope, and, when it reaches the bottom, is agitated for a few moments, when the sand is forced up through the valve, and thus withdrawn from the well, when the boring is again resumed.
As the work proceeds, a register is kept by the judicious borer of the different strata passed through, and also of the veins of water and oil passed through, in order to the formation of an intelligent judgment in tubing the well.
As might be supposed, this operation of descending amid the rocks is not without its difficulties and discouragements. Sometimes the bit breaks or becomes detached from the auger stem, leaving a fragment of hardened steel, or an entire bit, deep in the recesses of the rock. When the latter is the case, recourse is had to divers expedients, by means of implements armed with sockets and spring jaws, in order to entrap the truant bit. And it is marvellous what success generally attends these efforts to extract bits that are oftentimes two or three hundred feet below the surface. Sometimes, however, these efforts fail, and the well must be abandoned, with all the labor and anxiety that have been expended upon it.
During the progress of the boring there is more or less carburetted hydrogen gas set free. This supply is so abundant at times as to cause an ebullition in the water of the well, resembling the boiling of a pot. In the case of the flowing wells, when the vein of petroleum is reached, the gas rushes forth with such violence, and the upward pressure is so furious, as to force the implements from the well, and even the tubing, when not properly secured, has been driven through the derrick in its upward progress.
After the boring has been successfully accomplished, the next operation consists in tubing the well. This is merely the introduction of a copper or iron chamber, extending down, or nearly so, to the vein of the oil. This tubing is, for the pumping and larger-class flowing wells, usually about two and a half or three inches in diameter, consisting of sections about twenty feet in length, and connected together by means of screw and socket joints. As there are usually many veins of water passed through in boring, some device must be resorted to in order to shut off this water from the oil vein and produce a vacuum. This is accomplished by applying what is called a 'seed bag' to the tube at the point where this stoppage is desirable. The seed bag is a tube of strong leather some eighteen inches in length and about five inches in diameter. It is put around the metallic tube and the lower end firmly tied around it. From a pint to a quart of flaxseed is then poured in, and the upper end bound rather more slightly than the lower, when the tube is sunk to its place in the well. In a few hours the flaxseed in the sack below will have swollen and distended the bag so as to effectually shut off all water from above. When it is desirable to withdraw the tubing from the well, the effort of raising it will break the slight fastening at the upper end of the leathern sack, permitting the seed to escape and the tube to be withdrawn without difficulty. When the well is to be pumped, a pump barrel is placed at the lower end of the tube, with piston rods extending to the top and attached to the working beam used in boring the well.