Drilling inexpensive, small diameter "microholes"
using easily transportable coiled tubing equipped with
miniaturized seismic and other geophysical instruments could
lead to much cheaper oil and gas exploration.
In exploring for oil and gas in the 21st century,
smaller may be better.
The Department of Energy's Los
Alamos National Laboratory is announcing this week that recent
field experiments have enhanced prospects for "microdrilling"
technology - a concept that could offer a revolutionary, lower cost
approach to oil and gas exploration.
According to the Laboratory, the new technology currently allows
for drilling holes up to 500 feet deep with all the equipment
carried on a tandem-wheel trailer pulled by a standard pickup truck.
When developed for deep drilling, the technology will replace
traditional methods that use massive amounts of equipment, material
and manpower, all of which are extremely expensive.
The concept could be a significant step toward futuristic
"rig-less" drilling that could reduce the visual impact
that has contributed to public objections to drilling in some areas.
Last month, four microholes with diameters two to five times
smaller than conventional holes were drilled to depths of 300 to 500
feet in alluvium and lake sediments by staff from the Laboratory's
GeoEngineering group. The work was supported by a major energy
company in concert with DOE's Natural Gas and Oil Technology
Microdrilling technology was highlighted as a likely
"success story" emerging from the Energy Department's oil
and natural gas research program. According to DOE's Oil and Gas
RD&D Programs, released in February 1999, future
microdrilling systems could occupy a space roughly 1/20th that of a
typical rig and cost about 90 percent less.
Companies using microdrilling would also realize additional
savings because the technology could ultimately require only about a
barrel of fluid per 1,000 feet of drilling to lubricate the bit and
motor and remove dirt, whereas conventional drilling requires about
40 barrels of fluid per 1,000 feet.
The Los Alamos experimental fieldwork showed that drilling
small-diameter microholes is both feasible and ideally suited for
data collection using miniature sensors. For example, in this
experiment Los Alamos scientists used for the first time a
microelectromechanical system accelerometer to collect subsurface
"Future microholes will be drilled so inexpensively that
companies can use them to do things they've never done before,"
said Earl Whitney, a project leader in the Laboratory's Earth and
Environmental Systems Division. "By using the microholes to
deploy newly-miniaturized seismic and other geophysical instruments,
the industry can study vast areas of potential production at an
enormous reduction in cost."
The microdrilling technology is based on the miniaturization of
conventional coil tubing techniques that deploy a drill motor and
bit on the end of tubing coiled around a spool. The recent test
drilled 2 3/8-inch diameter microholes lined with 1 1/4-inch flush
joint PVC tubing. Drilling fluids are run through the tubing to turn
the motor and drill bit.
In place of the usual large mud tanks needed to capture what's
dug out of the ground, much smaller tanks suffice.
"Cleanup is expensive for conventional drilling
methods," Whitney said. "By greatly reducing the size of
the drilling site, we not only reduce the overall drilling costs but
the environmental impact, which can be even more expensive."
The team is developing an even smaller motor and bit system that
could allow drilling to 10,000 feet, deep enough to explore most of
the world's potential oil and gas reserves. Concurrently, plans
include broadening the project's focus to include miniaturization of
standard borehole tools used today in drilling operations to study
oil and gas reservoirs.
The project is being co-funded by the Federal Energy Technology
Center (FETC), a field facility of DOE's Office of Fossil Energy.
FETC, colocated in Morgantown, WV, and Pittsburgh, PA, is one of the
Federal participants in the Natural Gas and Oil Technology
Partnership. The 10-year-old Partnership was formed at Los Alamos
and Sandia National Laboratories to offer their scientific
capabilities to the oil and gas industry. Under this arrangement,
the DOE pays for the scientists' time and the industrial partners
share other costs of research and testing.