Extraction (Technically termed Production.)—The earliest system adopted for the collection of petroleum appears to have consisted in skimming the oil from the surface of the water upon which it had accumulated, and Professor Lesley states that at Paint Creek, in Johnson county, Kentucky, a Mr George and others were in the habit of collecting oil from the Early Methods. sands, “by making shallow canals 100 or 200 ft. long, with an upright board and a reservoir at one end, from which they obtained as much as 200 barrels per year by stirring the sands with a pole.” It is said that at Echigo in Japan, old wells, supposed to have been dug several hundred years ago, are existent, and that a Japanese history—called Kokushiriyaku, states that “burning water” was obtained in Echigo about A.D. 615.
The petroleum industry in the United States may be considered to date from the year 1859, when the first well avowedly drilled for the production of oil was completed by E. L. Drake. The present method of drilling has been evolved from the artesian well system previously adopted for obtaining brine and water. The drilling of petroleum wells is carried on The United States. by individuals or companies, either on lands owned by them, or on properties whose owners grant leases, usually on condition that a certain number of wells shall be sunk within a stated period, and that a portion of the oil obtained (usually from one-tenth to one-fourth) shall be appropriated as royalty to the lessor. Such leases are often transferred at a larger royalty, especially after the territory has been proved productive. The “wild-cat” wells, sunk by speculators on untested territory or on lands which had not previously proved productive, played an important part in the earlier mapping out of the petroleum fields. To discourage the sinking of wells on land immediately adjoining productive territory, it has been usual to drill along the borders of the land as far as practicable, in order to first obtain the oil which might otherwise be raised by others, and on account of the small area often controlled by the operator, the number of wells drilled has frequently been far in excess of the number which might reasonably be sunk. Experience has proved that in some of the oil fields of the United States one well to five acres is as close as they should be drilled.
After the selection of the site, the first operation consists in the erection of the rig. The chief portion of this rig is the derrick, which consists of four strong uprights or legs held in position by ties and braces, and resting on strong wooden sills, which are preferred, as a foundation, to masonry. For drilling the deeper wells, the derrick, on accountOil Derrick. of the length of the “string” of drilling tools, is usually at least 70 ft. high about 20 ft. wide at the base, and 4 ft. wide at the summit. The whole derrick is set up by keys, no mortices or tenons being used, and thus the complete rig may be readily taken down and set up on a new site. The samson-post, which supports the walking beam, and the jack-posts, are dove-tailed and keyed into the sills. The samson-post is placed flush with one side of the main sill, the band-wheel jack-post being flush with the other side, so that the walking-beam, which imparts motion to the string of tools, works parallel with the main sill.
The boiler generally used is of the locomotive type and is usually stationary though sometimes a portable form is preferred. It is either set in the first instance at some distance from the engine and well or is subsequently removed sufficiently far away before the drill enters the oil-bearing formation, and until the oil and gas are under control, in order to minimize the risk of fire. A large boiler frequently supplies the engines of several wells. The engine, which is provided with reversing gear, is of 12 or 15 horse-power and motion is communicated through a belt to the band-wheel, which operates the walking-beam by means of a crank. The throttle-valve is opened or closed by turning a grooved vertical pulley by means of an endless cord, called the telegraph, passing round another pulley fixed upon the “headache-post,” and is thus under the control of the driller working in the derrick. The headache-post is a vertical wooden beam placed on the main sill directly below the walking-beam, to receive the weight of the latter in case of breakage of connexions. The position of the reversing link is altered by means of a cord, passing over two pulleys, fixed respectively in the engine-house and on the derrick. At one end of the band-wheel shaft is the bull-rope pulley, and upon the other end is a crank having six holes to receive a movable wrist-pin, the length of stroke of the walking-beam being thus adjusted. The revolution of the bull-wheels is checked by the use of a powerful hand-brake.
The band-wheel communicates motion to the walking-beam, while drilling is in progress, through the crank and a connecting-rod known as the pitman; to the bull-wheels, while the tools are being raised by the bull-rope; and to the sand-pump reel, by a friction pulley, while the sand-pump is being used. It is therefore necessary that the machinery should be so arranged that the connexions may be rapidly made and broken. The sand-pump reel is set in motion by pressing a lever, the reel being then brought into contact with the face of the band-wheel. The sand-pump descends by gravitation and its fall is checked by pressing back the lever so as to throw the reel against a post which serves as a brake.
The drilling tools are suspended by an untarred manila rope 2 in. in diameter, passing from the bull-wheel shaft over a grooved wheel known as the crown-pulley, at the summit of the derrick. The string of drilling tools consists of two parts separated by an appliance known as the jars. This piece of apparatus was introduced by William Morris in 1831,Drilling Tools. and consists of a long double link with closely-fitting jaws which, however, slide freely up and down. It may be compared to a couple of elongated and flattened links of chain. The links are about 30 in. long and are interposed between the heavy iron auger-stem carrying the bit and the upper rod, known as the sinker-bar. Their principal use is to give a sharp jar to the drill on the upstroke so that the bit is dislodged if it has become jammed in the rock. In addition to the appliances mentioned the tools comprise reamers to enlarge the bore of the well, the winged-substitute which is fitted above the bit to prevent it from glancing off, and above the round reamer to keep it in place, a temper-screw with clamps and wrenches. Sand-pumps and bailers are also required to remove detritus, water and oil from the bore-hole.
The action of the jars and temper-screw has been described by John F. Carll as follows: “Suppose the tools to have been just run to the bottom of the well, the jars closed and the cable slack. The men now take hold of the bull-wheels and draw up the slack until the sinker-bar rises, the ‘play’ of the jars allowing it to come up 13 in. without disturbing the auger-stem. When the jars come together they slack back about 4 in., and the cable is in position to be clamped in the temper-screw. If now the vertical movement of the walking-beam be 24 in., when it starts on the up-stroke the sinker-bar rises 4 in., and the cross-heads come together with a smart blow, then the auger-stem is picked up and lifted 20 in. On the down-stroke, the auger-stem falls 20 in., while the sinker-bar goes down 24 in. to telescope the jars for the next blow coming up. A skilful driller never allows his jars to strike on the down-stroke, they are only used to jar down when the tools stick on some obstruction in the well before reaching the bottom, and in fishing operations. An unskilful workman sometimes ‘loses the jar’ and works for hours without accomplishing anything. The tools may be standing at the bottom while he is playing with the slack of the cable or they may be swinging all the time several feet from the bottom. As the jar works off, or grows more feeble, by reason of the downward advance of the drill, it is ‘tempered’ to the proper strength by letting down the temper-screw to give the jars more play. The temper-screw forms the connecting link between the walking-beam and cable, and it is ‘let out’ gradually to regulate the play of the jars as fast as the drill penetrates. When its whole length is run down, the rope clamps play very near the well-mouth. The tools are then withdrawn, the well is sand-pumped, and preparations are made for the next ‘run.’ ”
The ordinary sand-pump or bailer, consists of a plain cylinder of light galvanized iron with a bail at the top and a stem-valve at the bottom. It is usually about 6 ft. in length but is sometimes as much as 15 or 20 ft., and as its valve-stem projects downwards beyond the bottom, it empties itself when rested upon the bottom of the waste-trough.
The operation of drilling is frequently interrupted by the occurrence of an accident, which necessitates the use of fishing tools. If the fishing operation is unsuccessful the well has to be abandoned, often after months of labour, unless it is found possible to drill past the tools which have been lost. In readiness for a fracture of the drilling tools or of the cable, special appliances known as fishing tools are provided. These are so numerous and varied in form that a description would be impossible within the scope of this article. The fishing tools are generally attached to the cable, and are used with portions of the ordinary string of tools, but some are fitted to pump-rods or tubing, and others to special rods.
The drilling of a well is commonly carried out under contract, the producer erecting the derrick and providing the engine and boiler while the drilling contractor finds the tools, and is responsible for accidents or failure to complete the well. The drilling “crew” consists of two drillers and two tool-dressers, working in pairs in two “tours” (noon toDrilling the Well. midnight and midnight to noon).
The earlier wells in Pennsylvania consisted of three sections, the first formed of surface clays and gravels, the second of stratified rocks containing water, and the third of stratified rocks, including the oil-sands, usually free from water. The conductor, which was a wooden casing of somewhat greater internal diameter than the maximum bore of the well, passed through the first of these divisions, and casing was used in the second to prevent percolation of water into the oil-bearing portion. In later wells the conductor has been replaced with an 8-in. wrought-iron drive-pipe, terminating in a steel shoe, which is driven to the bed-rock, and a 778-in. hole is drilled below it to the base of the lowest water-bearing stratum. The bore is then reduced to 558 in., and a bevelled shoulder being made in the rock, a 558 in. casing, having a collar to fit water-tight on the bevel shoulder, is inserted The well is then completed with a 512 in. bit. As the water is shut off before the portion of the well below the water-bearing strata is bored the remainder of the drilling is conducted with only sufficient water in the well to
