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from
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New electric drilling techniques can
overcome many of the stumbling blocks encountered by traditional
boring methods. Researchers at the Los Alamos National Laboratory
(Los Alamos, NM) are using electricity for a new type of soil
penetration -- rock melting. This technology, called Subterrene,
works especially well for environmental drilling in poorly
consolidated soils in which conventional rotary equipment has
difficulty. It also has excellent insulation capabilities for
cables, wires, and pipes and can be used to anchor structures.
The Subterrene makes vertical or horizontal holes in rocks and soils
by using an electrical resistance heater operating at about 2800
degrees Fahrenheit. The melted rock is chilled into glass to form a
dense, strong, firmly attached hole-lining which can be used to
contain contaminants, to stabilize structures, or to insulate pipes,
cables or wires. The device requires no lubricants or casings, nor
does it use chemicals, detergents, plastics or metals. Moreover, it
minimizes the remobilization of in situ waste.
Other advantages:
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All in one. The three major facets
of excavation -- rock fracturing, debris removal, and wall
stabilization -- are all accomplished in a single integrated
process.
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Precision. The Subterrene can make
lined holes of precise diameter, useful for anchoring structures
such as bridges, TV towers, and transmission line towers. This
also means that holes for anchoring pipeline supports can be
made quickly in difficult terrain, such as Alaska permafrost.
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Coring capabilities. Geophysical
prospectors like to extract undisturbed core samples to identify
rock layers. A coring subterrene penetrator can extract a sample
which remains thermally unaltered at the center.
"The technology is ideal for
environmental drilling, for sensor placement, and for remediation,"
says Jim Blacic, technical support at Los Alamos. The process can be
used where you want to prevent spread of contaminants or as
insulation for conduits for telecommunications. The Subterrene is
also great for making holes in hot rocks. Because the action of the
device depends on melting, the rocks high initial temperature
reduces the power needed to form the hole. This enhances the
penetration rate, making the Subterrene a super idea.
Not Yet
Off the Ground
Blacic believes his new technology, still in research and
development, holds great promise for a number of sectors, including
the electric utility industry. Transmission lines for electric power
are currently laid in trenches. Maintenance work cannot be done
without disrupting the environment. The Subterrene would drive
horizontal holes for utility emplantments with minimal disturbance
to ground surface. This would mean efficient, high-capacity
underground transmission lines that allow easier, cleaner and faster
maintenance. Oil service companies are also looking at the
Subterrene's potential as a stabilizer for weak zones during oil and
gas drilling.
Where does the technology go from here? Blacic says it depends on
the level of support. Some applications are closer than others. For
shallow drilling of poorly consolidated soil, commercialization will
probably occur within a few years, he says.
Electric
Drilling, Soviet-Style
One method, developed by the former Soviet Union, simply uses
electricity as a fuel source for drilling. According to a report by
Russian scientists, translated and published in Oil & Gas Journal,
electro drilling has three inherent advantages over turbo, rotary,
and positive displacement motor systems. These advantages are
applicable to electricity in the broad sense:
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Inexpensive. Electricity is
relatively cheap and convenient for long-distance
transmission.
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Adaptable. Electricity can be
easily and efficiently transformed into other kinds of
energy, permitting the use of automated technologies and
remote control.
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Constant. It can maintain a
constant high power by compensating for transmission power
losses through voltage increases.
Though electro-drilling has not caught
on in the U.S., the Soviets have been using it for years as an
alternative to rotary, turbo, and positive displacement motor
systems. The first electric downhole motor was developed in the
Soviet Union in the late 1930s. Research was disrupted during World
War II, then resumed in 1947. Despite many incidences of improved
drilling performance, users found some disadvantages and
inconsistencies, including lengthy down time, poor longevity,
pressure loss, and limitations regarding size of the drill (large)
and direction (down only).
Improvements in the past 30 years
remedied these problems and considerably increased the reliability
and flexibility of electro drilling. Russian scientists believe the
technique will find wide applications in the coal industry, mining,
underground railway construction, trenchless pipe laying and other
areas.
For more information on rock melting, contact Jim Blacic at
Los Alamos at 505/667-4318 or visit
www-emtd.lanl.gov
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