Surface Machinery and Methods for Oil-Well Pumping Page: 53

We have had considerable experience with electric motors and gas engines
and as a result of that experience we knew it would be inadvisable to place
either a gas engine, an electric motor, or an oil engine in close proximity to
any of these active wells as danger of fire was too great. In this field it is
necessary to take every precaution to eliminate the fire risk.' Even so, we
have had several disastrous fires. For that reason we use only steam for
The gas engine is widely used to pump oil wells, especially in oil
fields with low gas supply. It has high thermal efficiency, and at
many wells it burns natural gas that would otherwise be wasted.
By the use of the reversible gear the gas engine gives good service
for bailing, pulling, or swabbing. It is more flexible than the oil
engine, is lighter and cheaper, and is more readily started and re-
started, but it is not so adaptable as the steam engine.
Table 4 shows comparative costs of gas engines and electric motors
for oil-field pumping and cleaning for one of the larger oil com-
Another oil company operating in one of the Mid-Continent oil
fields has given the following comparison of gas engine and electric
motor maintenance for a year. There were 367 wells pumped by gas
engine and 241 wells by electric motor, all on the beam and from
about the same depth.
367 wells pumped by gas engine.
Average cost per well
Repairs- per month.
Labor-_- -_____-_______ $5.33
Material_ __ ___________ 18. 81
Total -_--_---_ ____-- -------- _ 24.14
241 wells pumped by electric motor.
Average cost per well
Repairs- per month.
Labor__-__ __ __ _______ $1. 66
Material ....... . ______-__ _____ 2.98
Total-_ -__________ 4. 64
TABLE 4.-Comparative costs of gas engine and electric motor for pumping
and cleaning.
Generating electrical energy__--------------------------- 1.04 cents per kw. h.
Purchasing electrical energy -------------------------- 1.1 cents per kw. h.
Cost of installing 15/30-hp., 6 to 12-pole, 440-volt, 50 to
60-cycle motor------------------------------------ $3,175.00
Cost of installing 35-hp. gas engine, including reverse
gear ------------------------------------- 3,155.00
Yearly cost of operating gas engine-- ...1,255.62
Yearly cost of operating 15 to 30 hp. motor-............ 798.94
Saving by motor over engine operation-- ........ 456.68

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George, H. C. Surface Machinery and Methods for Oil-Well Pumping, report, 1925; Washington D.C.. ( accessed July 22, 2017), University of North Texas Libraries, Digital Library,; crediting UNT Libraries Government Documents Department.