THE IRRIGATION AGE. 



395 



30-inch wells near Plain View, Texas, for about one 

 year. In a recent letter the well driller said they were 

 drilling wells an average of 250 feet deep and they 

 were at that time sinking a well on an average of 

 eight days, including time of erecting and taking 

 down derrick; the average drilling time being from 

 three to three and one-half days. In this territory no 

 rock is encountered and 'conditions are therefore most 

 favorable for rapid work. 



Figure 1 is a general view of the equipment show- 

 ing only the lower part of the derrick. Figure 2 is 

 a view of the entire derrick. Figure 3 

 illustrates a part of the equipment and 

 shows in the foreground a special type 

 of drill sometimes used. Figure 4 shows 

 the type of drill 

 generally used in 

 earth work. Fig- 

 ure 5 illustrates the 

 type of drill used 

 in reaming out an 

 earth drill hole. 



The derrick of 

 this equipment is 

 45 feet high and 20 

 feet square at the 

 base. It is illus- 

 trated equipped 

 only with a rotary 

 machine for drill- 

 ing large wells, but 

 the same outfit can 

 be arranged as a 

 combination ma- 

 chine to operate 

 either by the ro- 

 tary or churn drill 

 methods by the ad- 

 dition of a walking beam to connect with a solid line of 

 well tools. This machine has a powerful hoisting drum 

 placed in the front of the derrick frame which is used 

 in connection with heavy pulley blocks and wire cable 

 to lift and lower the rotary tools, or well casing, as may 

 be required. The rotary machine is driven by chain 

 belt from the machine shafting. The rotary is pro- 

 vided with powerful grippers so designed that they 

 firmly hold either the drill rods, or well casing, when 

 being rotated down into the well and at the same 

 time permit the drill rods, or casing, to be raised or 

 lowered as required. 



The drill rod is usually 4 or 6 inch heavy wrought 

 iron pipe coupled together with strong taper thread 

 couplings. These rods are connected to the pulley 

 block by a roller bearing rotary swivel and this swivel 

 also has a connection for a water hose. On the outer 

 end of the truck, carrying the engine, is a pressure 

 pump, which may be either steam driven from any 

 source of steam supply or chain belt driven from the 

 machine shafting. The pump is connected to the 

 rotary by piping carried up into the derrick and 

 having two hose connections controlled by a three- 

 way cock. 



The hose connection not in use is connected to 

 another swivel, which is joined to a length of piping 

 and hoisted into the derrick during the time of opera- 

 tion. When it is desired to add another length of 

 pipe it is only necessary to unscrew the swivel from the 



FIGURE 4 (at left) Type of drill used 

 generally in earth work in drilling 30-inch 

 wells. 



FIGURE 5 (at right) Type of drill used 

 in reaming out an earth hole. 



pipe in the drill hole, screw on the other length of 

 pipe, turn the valve cock to connect with this pipe and 

 continue the drilling operation. The connection is 

 usually made without stopping the pump. The two 

 hose connections are illustrated in Figure 1. 



The drill bit for drilling large wells in earth 

 formation has been developed after many experiments. 

 The drill bit most extensively used at the present time 

 is illustrated in Figure 4 and consists of a fish tail 

 bit having two water orifices, one on each side of the 

 shank. Immediately above this bit is a 5-blade bit 

 for enlarging the drill hole to the required diameter. 

 If a test drill hole has been first made and it is 

 desired to ream it out to larger diameter, the bit 

 shown in figure 5 is used for this purpose. With this 

 bit the end of the pipe extending down into the smaller 

 drill hole forms a guide to produce a straight drill 

 hole. 



When a test drill hole is first made this should 

 not be less than 8 inches in diameter, since ex- 

 perience has proven that a drill hole this size can be 

 made at as small cost as one of smaller size and the 

 larger drill hole affords better opportunities for test- 

 ing and also forms a better guide for enlarging the 

 hole. A drill like the one illustrated in Figure 3, con- 

 sisting of a fish tail bit with two 5-prong bits immedi- 

 ately above it, the upper one being the full size of the 

 drill hole and the lower one of an intermediate size, is 

 sometimes used but drillers generally prefer the bit 

 shown in Figure 4. 



In operation the drill tools are suspended from 

 the top of the derrick and extend through the rotary 

 machine, which is shown on the derrick floor. The 

 suction pipe of the pressure pump is led into a shal- 

 low basin excavated in the ground close to the derrick 

 and a trench is cut leading by a circuitous route from 

 the center of the derrick, where the well is located, to 

 this basin. The object is to have the circulating water 

 travel a considerable distance before reaching the 

 settling basin, thus permitting the sand to settle in the 

 trench from which it may be shoveled. The nature of 

 the formation can be ascertained at any time by 

 examining the sand in this trench. The basin is filled 

 with water from any convenient source. 



When the drill rods are connected with drill and 

 suspended in derrick, work is commenced by turning 

 on the water which flows down the inside of the 

 piping and out through the two orifices in the upper 

 part of the fish tail bit. The pipe is then gripped in 

 the rotary and turned at a speed of 40 to 100 revolu- 

 tions per minute, according to the nature of the work. 

 By means of a powerful friction brake the drill rods 

 are lowered as fast as the bit will cut away the ground 

 and the water circulation carry the excavated material 

 to the surface. New lengths of pipe are added as re- 

 quired. The circulating water is usually allowed to 

 become puddled with the clay carried in suspension. 

 This clay is necessary to the success of the work. If 

 clear water were pumped into a sand formation it 

 would be rapidly absorbed by the sand the circulation 

 soon stopped. This is especially true when the sand 

 is coarse and water bearing. The clay will not flow 

 through sand to great extent and soon forms a water 

 seal which not only prevents waste of water but 

 prevents caving of the sand. This process is known 

 as mud walling a hole and is so effective that holes 

 (Continued on Page 415) 



