NAME OF WELL. Columbia Farm (Old Story Farm,) on Oil Creek, one mile below Petroleum Babcock.. 36 Stewart.. 18 276 Reiter 18 Jones. 27 Blocher 30 No. 58.. 27 59. 18 61. 21 458 62.. 27 64.. 27 66.. 18 66 69.. 24 the old filled up valley of the Tunauquaut, at Tarport, McKean Co. Pa. from 200 to 300' of this casing is required in each well. 66 Wells are spoken of indiscriminately as "small holes" or "wet holes" on the one hand, and as "cased holes" or "dry holes" on the other. A "small hole" must necessarily be a "wet" one, for there is no room to case off the water while drilling; and a 'cased hole" must necessarily be a "dry" one, if the casing accomplishes the purpose for which it is used. If now a well is to be drilled “wet,” that is if no effort is to be made to shut off the water which comes into it from the second division mentioned above, to keep it from following the drill down to the oil rocks, then this "conductor" of which we have been speaking, whether of wood, castiron or casing, needs only to be 6" in diameter, inside measurement. But if the well is to be drilled "dry," an 8" conductor must be used, as will be seen further on. In the first case (for a wet well), after the conductor is in place, a plain 54" hole is drilled all the way to the oil rocks; the water, meantime, nearly filling the well, or perhaps overflowing at the top of the conductor. In the latter case (for a dry hole), an 8" hole is to be drilled from the bottom of the conductor to a point below the water veins. When this is * These are evidently errors in Nos. 116, 137 and 138 as the bottom of the Stray S. S. as here given overlaps upon the 3d S. S. done, a 5ğ" casing (inside diameter) is inserted, with a device on the bottom so arranged that it will form a water tight joint between the casing and wall of the well. A 5' hole is then continued down to the oil rocks from the inside of this last "string of casing." If the casing has been inserted to the proper depth and no water is encountered below it, the sand-pump will soon exhaust the water in the process of drilling, and the well be perfectly dry. But if lower veins of water are struck, the casing must be drawn, the hole reamed out to a greater depth, and the casing continued down below them. After the water is exhausted, a few pails full are poured in as circumstances demand; to moisten the drillings and furnish fluid for the sand-pump. Comparing now the two wells when completed and ready for the pump, we find them both to be of the same size, 5" in diameter. One has simply a conductor through the upper division, all the stratified rocks being bare, is full of water, and has probably shown but very little indication of oil. The other has a conductor through the upper division, casing inside of this to the bottom of the middle division, and is dry-or at least was dry until the striking of the oil sand, when it immediately filled up several hundred feet with oil, or perhaps flowed. The "dry" well is ready at once for the introduction of the pump tube; the "wet" one must be cased before it is tubed. The casing used for this purpose ("small casing,") is of 34" inside diameter. A "water packer" or "seed bag" is attached to its lower end, which effectually closes the annular space between the outside of the casing and wall of the well. This "small casing," of course, must extend down to the bottom of the second division, the same as the large casing does in the "dry" well, for it has precisely the same duty to perform, the shutting off of the water in the upper rocks from the well shaft. The well is now tubed with the ordinary 2" "tubing," having a "working barrel" or pump chamber at the bottom, which is placed at or near the point where the oil enters. Inside of the "tubing" are inserted the "sucker rods" which are connected in the derrick to the "walking beam," and operate the pump valves below. Upon starting the pump, the "water packer" prevents any of the fluid outside of the casing from entering the well, and the water inside of the casing and in the uncased portion of the well is soon pumped out and the well is said to be 'exhausted." As the well exhausts, the oil, which has been held back in the rock by the pressure of the heavy column of water above it, gradually forces its way into the well and is raised by the pump to the surface, unless it has a sufficient force of gas to flow of its own accord afterwards. |