WELL-SINKING (A". well, icl, well, spring, 01-IG. ?crib', Ger. II!, wave, billow, trout AS. weallan, t cruNun Ger. imIlcoo, to well, boil op; connected with I.ttIi. rdais, ()Church Slay. rl finu. wave, billow, Lat. voircre, Ilk. cilycin. to turn. Skt. nriai, wave). The digging, boring. or drilling of holes in the earth for the development of supplies of water, petrolemn. natural gas, or salt. The process is generally accompanied or immediately followed by the curbing or easing of the well to prevent it being choked by the material penetrated, or to shut out all liquids except the yield of the stratum which the well is designed to tap. Besides the development of subterranean liquids. wells or their equivalent in construction are also used in prospecting for solid utinaa•nls and in determin ing the charaeter of soil and rock, foundations, and other engineering structures. Wells vary in diameter from 1 inch to 100 feet and in depth front 5 feet to 0000 feet. The methods of sink ing employed depend upon the character and depth of the material penetrated, rather than the object for which they are sunk. Wells are classified according to the methods of sinking, as dug, drilled, bored, driven. and jet; by the lining employed, as curl; tube, and case; as open, in the case of relatively large, shallow wells; as shallow or deep; and as artesian, flow ing, n01'1-flowing, or pumping, as the case may be.
Wells from a few feet to a hundred or so in diameter and depth are generally sunk by means of picks and shovels, or by digging. The sides frequently require to be supported while the sinking is under way, particularly if quicksand or large quantities of water are encountered. Sheet-piling or planks driven into the ground at the outer edge of the excavation may he em ployed, with proper crosi;hracing where neces sary, or a woolen or metal crib or caisson pro vided with a shoe or cutting edge may be used. The latter generally sinks of its own weight if the material within the well is removed. The
sinking process may lie and generally is aided by building the curb or lining wall directly on the shoe. the increasing weight gradually forcing the shoe and curl) downward. Nore or less water is likely to be encountered. It may be re moved by a centrifugal pump, a pulsometer, or a direct-acting steam pump. Small wells of no great depth, provided with a metal tithing or casing. are often driven by hammer blows, whence the name driven or tubular The tubes thus driven may have solid, pointed ends Or drive points, or their lower ends may lie open. In any case the lower sections must be perfo rated. Both round holes and slotted holes are employed. and where very fine material is en countered gauze wire strainers may be necessary. If the well-casing is open at the bottom the Ma terial pierced must be removed by sand pumps or buckets, or by a hydraulic or steam jet. Arte sian \yells and most other deep wells penetrate more or less rock. Some shallow wells also go through or into rock, particularly in prospecting for coal and the like, or in exploring for founda tions. In all such cases resort is had to drill ing. For relatively small and shallow holes ordi nary hand drills and diamond drills may he used. (See Thum—) But in most operations for water, gas, rind oil wells. a regular drilling rig is necessary after rock is struck. So long as the sinking is through sand or other easily worked material, wrought-iron or steel tubing may be driven down with mauls, either by hand, horse, or steam power: by means of a or by the sand pump or bucket method, combined with rotation of the tube or easing. 'I he hydraulic jet is simply a stream of water under pressure introduced at the bottom of the well through a supply pipe, or through a hollow drill. The force of the water aids in loosening the material and also brings it to the surface. The sand pump or bucket is a simple form of pump, low ered into the well hole, filled, raised, and emptied.