The general type of motor is rated at 75 hp., 3-phase, 60-cycle, 440-volt type motor. A recent motor in California is rated at 100 hp. Over 200 motors are in use for drilling.
The improved motors are so controlled that they have 80 speed variations. The cost of installing a motor is no greater than that of drilling engines and boilers, and the economy is evident. For all places where it is available, the use of elec tricity is advised.
Costs of costs in new untested areas are not easy to determine in advance. If all goes well, the costs may be low. Accidents and natural occurrences such as floods, fires and storms, may tie up drilling wells for weeks or even months in cases where new supplies must be ordered. The accessibility of the region is a big factor. If easily reached, the cost of haul age may be small, say or $5 per ton, but in some areas $30 to ..? 0 per ton may be charged.
Drilling costs fall under the headings Labor, Material, Fuel, Water, Teaming, and Overhead.
Labor includes " rigging up." Drilling material includes rig and casing.
It may be necessary to include the cost of a pipe line, pump, and use of water, under the heading Water.
Teaming is always an item of expense. Teaming may be by horse, by ox teams, or by truck.
Overhead includes superintendence and camp supplies.
Drilling costs vary greatly. To purchase a complete new outfit and drill a hole 3500 ft. deep in California will cost not less than $100,000. In Wyoming a hole of the same depth can be drilled for $80,000.
In Oklahoma a test 3500 ft. deep can be drilled for $80,000.
In Texas a 3500-ft. test will cost $80,000.
In Ohio a 3500-ft. test will cost under ordinary conditions $35,000.
It must be understood that a "dry" hole or failure will not cost as much by any means.
The tools, casing and rig can be salvaged. In some deep holes the value of tools, casing, and rig amounts roughly to 50 per cent of the value of the hole.
If the holes were drilled by a contractor who furnishes tools and everything except casing, the costs would be about as given below.
Shallow wells drilled with portables 250 to 500 ft. may be completed at a cost of $1000 to
$1500. Wells 900 to 1000 ft. cost $3500 to $5000. Wells of 2000 to 2500 ft. cost in Cali fornia $50,000 to $60,000. In Wyoming such wells cost $25,000 to $35,000. In Oklahoma $15,000 to $20,000. In Texas $15,000 to 25,000.
The first hole is generally the most expensive. Once a field has been discovered later drilling costs are much lower.
Casing Lines.—The casing line extends from the calf wheel and over the derrick. One end of the casing line is attached to the pulley block or may be attached to a bar on top of the derrick, depending on the number of lines used.
The deeper the hole and the heavier the casing, the more lines are used. A single pulley block for 3 lines may be used at first, but as many as 11 lines may be necessary for deep holes.
The casing lines are strung over the casing sheaves so that the pulley block and hook center directly over the drill hole. This is essential to avoid binding. The number of lines required depends of course upon the weight of the casing to be handled. A sketch of the way casing lines are strung is shown in Fig. 27, p. 77.
The calf wheel is driven either by rope drive from a wheel on the end of the band wheel or by a sprocket-chain drive from a drive wheel on the end of the band-wheel shaft.
It is important here to speak of the cordage used in oil-field operations.
Cordage.—Two kinds of cordage are used in the oil fields.
Sisal hemp { Ordinary purposes (A) Rope Manila hemp f Drilling cables Bull ropes f Drilling lines Drilling j Casing lines Casing (B) Wire See Table 6 ) Sand lines Bailing Guy wires Support derrick Manila drilling cables (see Fig. 28) were used exclusively for many years, but the steeI-drilling cables (see Fig. 28, page 78) are preferable to manila cables. In a few places manila cables are used to drill shallow wells, or are used for "spudding" operations. Steel lines, however, can be used for all such purposes and are now cheaper.
Manila-drilling rope is sold by weight. It has diameters of 13 to 2% in. and weighs from % to 23 lb. per foot.