Page 59 - 4637

outboard. The fully enclosed oil bath rotaries came into general
use in the 1930s.
Until the late 1960s the largest rotary machine in general use
weighed about 10,000 lb and had a round opening of 27 in.,
whereas the rotary used to drill the Lucas well weighed about 2000
lb and had a round opening of perhaps 14 in. In the 1970s, to meet
the needs of offshore operations, 37,5 in. rotaries weighing
approximately 13,000 lb were developed to pass 36-in. conductor
pipe. More recently larger machines with 49%-in. round openings
and weighing approximately 25,000 lb have been placed on the
market and are proving popular.
Drill pipe tool joints replaced ordinary pipe couplings about
1910 or 1912, and seamless drill pipe replaced the lapweld or
"merchant's pipe" in the early 1920s. The first seamless drill pipe
had only a very light internal upset but a few years later the
internal upset was increased sufficiently to satisfy requirements for
the next 10 to 15 years.
Improvements in metallurgy, however, were required as
drilling depths increased. There is a continuing battle going on
between greater well depth and the development of drill strings
strong and durable. Alloy steels now are used extensively in drill
string components. During the steam rig era the philosophy
seemed to be "the bigger the better". The rotary rig used on the
Lucas well (1901) had only one boiler, such as used on cable tool
rigs, with a normal rating of perhaps 35 or 40 boiler horsepower
and a working pressure of 75 psi. The single cylinder steam engine
is reported to have been 9-in. bore by 12-in. stroke. The hoisting
equipment and rotary were likewise designed for light duty.
About 1915-16, heavy duty combination steam rigs were
developed for California operations. Such rigs used two 40-hp
boilers, one 14-in. x 14-in. single cylinder slide valve steam
engine, a double brake 2-speed drawworks and a 12-in. x 6 3/4-
in. x 14-in. duplex slush pump. The 23-in. rotary table was chain
drive with jaw-clutch on the pinion shall and open bevel gears.

58