TYPES OF WELLS 



69 



Although no two wells are exactly alike in all particulars, 

 there are, in reality, only a few distinct forms, the others being 

 simply modifications or combinations of these. The kind of well 

 to be sunk at a particular locality depends mainly on the nature 

 of the material to be encountered, one form being particularly 

 adapted to a certain material such as sand, while an entirely 

 different form is demanded if rock is to be penetrated. 



For deep waters entirely different types of wells are used. 

 These include: (i) the California or stove-pipe well sunk in thick 

 unconsolidated deposits by forcing down by jacks a sheet-steel 

 casing; (2) the standard drilled well sunk by the drop of a heavy 

 iron bit; (3) rotary process wells sunk by rotating a hollow bit 

 fitted with cutting shoe and (4) various forms of the so-called 

 hydraulic wells in which water is made to assist in the drilling. 

 Such wells are usually from 2 to 12 inches in diameter and require 

 heavy and often elaborate machinery for their sinking. They are 

 often of considerable depth, it not being uncommon to continue 

 drilling to depths of 1000 and sometimes 2000 feet if water is not 

 found at higher levels. 



The common deep-well methods and a few of their variations 

 are considered in more detail in Chapter XIV and statements 

 given as to the conditions to which they are adapted. 



Types of Curbings and Casings. Just as there are various 

 types of wells, so are there various methods of curbing and casing 

 (or lining) the well, each method being likewise particularly 

 adapted to a special type of well or to a certain definite kind of 

 material. The common types of curbings and the conditions to 

 which they are best adapted are shown in the following table. 



Types af well curbs and casings. 



