Page:Encyclopædia Britannica, Ninth Edition, v. 18.djvu/749

PETROLEUM 717 temper - screw the walking - clamped by the worked doVn- The free end d, which is bar of iron firmness to the upper link of steel, the slots placed that the driller in the derrick can easily control its motion by the use of cords and pulleys. A string of A ^ drilling tools is represented in fig. 1. First we have the a, which is attached directly to the end of beam, into the jaws of which the cable is set-screw b, and the long screw of which, c, is ward by the driller as the rock is penetrated. of the cable is fastened to the rope -socket screwed into the sinker-bar e, that is, a solid about 20 feet in length which serves to give tools. The sinker -bar is screwed into the the jars. The jars, /, consist of two links of of which are 21 inches long, with cross -heads 8 inches deep, in consequence of which the links have 13 inches of play. The lower link of the jars is screwed into another long iron bar called the 3 auger- stem, g, which is in turn screwed to the bit or , drill h. The jars are the : centre of action, and the . manner in which they per- ^ form their work may be best : vS explained, perhaps, in this -S*~ way. Suppose the tools to ~^*$^ have been just run to the ^j^EI bottom of the well, the jars . -;f^j closed, and the cable slacked, = the men now reel up the slack until the sinker - bar Q^sS: rises, the "play" of the jars allowing it to come up 13 inches without lifting the 5 auger-stem ; when the links come together they slack back about 4 inches clamp the cable into temper-screw. If now theQgPigp^ vertical movement of the ^ walking -beam is 24 inches, the sinker-bar rises 4 inches, when the cross-heads of the links come together with a smart blow ; then the auger- stem is picked up and lifted 20 inches. On the down- stroke the auger -stem falls 20 inches, while the links slide 4 inches carrying the sinker -bar down 24 inches. UJjjjj^M and O ;E= the ^l ~ 5 The links are never allowed Q-^si?;; to strike on the clown-stroke, Uj; while the blow of the up stroke prevents the drill from becoming wedged into any seam or crevice into which its weight might drive it. When the tools are all ready for operation, either a wooden conductor is placed perpendicularly in a sort of - shaft sunk to the bed-rock, cog or an iron tube called a " drive-pipe " is driven upon it through the soil. In either case great care is taken to ^ start the well perpendicularly <Q to the derrick - floor. The tools are swung into position from the top of the derrick, -j^ and the free end of the cable ^ is coiled around the shaft of W the reel in such a manner that when the free end is Q tightened the tools are lifted, 2 and when it is loose the reel- {/> shaft revolves within the .j coils. By holding the cable Q & firmh the tools rise, and as ^ it is loosened they fall. The |j ^ well is started in this man ^ ner and carried down until 5 g-^ Vy* ^ * "*" " a - v ^ 3j --r~ ^ *- -** the string of tools can be 9 = suspended beneath the walk- F g- 1- String of Tools. iug-beam,when a cable as long as the supposed depth of the completed OIL DELIVERY PIPE. well is wound upon the reel, the end carried over a pulley at the top of the derrick and then fastened into the rope-socket, the temper- screw attached, and the drilling continued to J-, the bottom of the well. Day and night the X machinery is kept in motion, one driller and T| one engineer and tool-dresser work from noon || 3M , ; until midnight, and another pair work from midnight until noon. The driller, with a short lever inserted in the temper-screw, walks round and round to rotate the drill. He watches the jars, and at intervals lets down the temper -screw. When the screw is run out or the drill needs sharpening, he arranges the slack cable so that it will run freely over the pulley and proceeds to "draw out." The cable is undamped from the temper -screw and the engine disconnected _L from the walking-beam and "- attached to the cable -reel. When all is ready the long cable is reeled up and the tools drawn out. The bit is replaced by one newly ~| sharpened, and after the well -^5 has been sand -pumped the S^Sf< tools are again lowered and gr2- drilling resumed. When the ^gir=;_ drilling proceeds without ac- ^ cident the work is exceed- ^ ingly monotonous. From the top of the bed- ?- rock to a point below the r&z surface-water of the region, ^fe^^SS^ the well is drilled of the same diameter as the, in- ~-.~=SHOZOH END terior of the drive -pipe. E DRIVE. PIPE This point is usually from p 300 to 400 feet below the g surface. At this point the m drill-hole is tapered, and a S pipe armed with a steel shoe iU is ground into the tapered hole to a water-tight joint, p The inside diameter of this f| casing-pipe is 5| inches, and mm below it the well is carried == down 5|> inches in diameter = to the bottom. The casing H I DERRICK FLOOR j C^SI^G pipe excludes the fresh sur- s face -water, and only water H enough is put into the well fj^ to wash out the drillings, j=r^^ unless salt water is encoun- =jj.ijjjjji^ tered. The casing-pipe be- ^^^ comes a permanent fixture, = into which is introduced the ^=s^^-^ 2-inch pipe, through which the oil flows or is pumped. This 2-inch pipe may be in- , troduced or removed at plea- ^ sure, without disturbing the J casing-pipe or drive-pipe, or < letting water into the well upon the oil. When drilling has been completed the well is tor pedoed. From one to twenty- five gallons of nitro-glycerin are lowered into the well in tin cylinders and exploded, usually by percussion. The effect of firing such a large = amount of this powerful * explosive is not apparent ^ at the surface, but soon a * gurgling sound is heard ap- , proaching from beneath ; the - oil rises from the well and - falls first like a fountain and then like a geyser, forming a torrent of yellow fluid, accompanied by a rattle of small stones and fragments __ of the canister in a shower ~- of spray 100 feet in height. Fi S- 2. Pumping Well. ^ The generation of such an enormous volume of gas in a limited area, the walls of which are already under a very high gas-pressure, /BOTTOM OF //a HOLE.