Energy-water consortium: Water use in horizontal drilling more efficient
than in vertical
By Eric Brown
Sunday, February 19, 2012
Extensive water use has been a source of concern as oil and gas companies
have gravitated toward horizontal drilling, but drillers can produce much
more energy per gallon of water through that technique than with vertical
drilling, civil engineers and water experts have discovered so far through
studies conducted in Weld County.
Kenneth Carlson, a civil and environmental engineering professor at
Colorado State University who serves as a co-director of the Colorado
Energy-Water Consortium, said this month that studies conducted by the
consortium have also discovered the average amount of water used per
completed horizontal well is about 2.8 million gallons — not 5 million
gallons of water, which is a commonly used figure.
And though about 400,000 gallons of water is used per vertical well,
studies have shown so far the energy returns are much better with
“Horizontal drilling requires a lot of water, no doubt … and I think
that has caused concerns for a lot of people in this area,” Carlson said.
“But if we in fact feel it’s necessary to pull this energy out from the
ground beneath us, it looks like horizontal drilling is a more
water-efficient way of doing it.”
In its research, the consortium concluded the water use for horizontal
wells was about 2.9 gallons of water per million BTUs of energy produced,
while vertical wells used 5.4 gallons of water per million BTUs of energy
A million BTUs of energy is the equivalent of about 8.5 gallons of gas,
All of the 445 wells examined in the study — the majority of which were
vertical, as horizontal drilling is still a relatively new technique —
used the hydraulic fracturing method. Hydraulic fracturing, or “fracking,”
involves blasting water, sand and chemicals into rock formations to free
oil and natural gas.
Carlson was in Evans this month talking about the consortium’s ongoing
studies, detailing those efforts to attendees of the West Greeley
Conservation District’s annual meeting.
Carlson explained at that meeting and in an interview last week that the
Center for Energy and Water Sustainability is a public-private partnership between
CSU and the oil and gas industry formed about a year ago. It is working to
solve issues related to water and the production of oil and gas in
The consortium spent the past six months examining 445 of Noble Energy’s
wells — all of which are in Weld County, and about 50 of which are
horizontal wells. The rest are vertical.
As Carlson explained, the shale formation from which oil is extracted is
about 7,000 feet deep underground, but the shale formation itself is
relatively shallow — only a few hundred feet deep.
The more commonly used vertical oil wells only go straight down and into
the underground shale formation to extract oil, but the technology used in
horizontal drilling allows those wells, once they reach the shale
formation, to drill horizontally through the shallow shale formation.
Because each individual horizontal well covers more area in the shale
formation, the ratio of water used per BTU of energy produced is much less
than vertical wells.
Carlson said water-use results may vary, depending on the region where the
drilling is taking place, and the companies doing the drilling.
During the meeting in Evans, Carlson also made note of the Colorado Oil
and Gas Conservation Commission’s recently published report projecting
that from 2010 to 2015 hydraulic fracturing will account for 0.1 percent
of the water diverted for beneficial use.
Although the recent water-use studies performed by the Colorado
Energy-Water Consortium and the Colorado Oil and Gas Conservation
Commission may lay to rest some concerns regarding water use in horizontal
drilling, experts spearheading the consortium, including Carlson,
acknowledge that horizontal drilling and fracking are not perfect
processes, and there is still plenty of research to be done and
improvements to be made.
Carlson said there are about 20,000 oil and gas wells in Weld County.
Because horizontal drilling looks to be used more often in Weld County and
because there are many questions surround the drilling technique, Carlson
said he and other water and engineering experts with the consortium will
continue with more in-depth research and hope to learn more about the
long-term effects of horizontal drilling, as well as fracking techniques.
For instance, he and others with the consortium agree there is potential
for better recycling of water in drilling operations, so less water would
have to be trucked in.
He also said at the meeting that if oil and gas companies are complying
with Colorado Oil and Gas Association rules — regulations that require
both a steel pipe and cement casing to serve as barriers between the wells
and the surrounding ground and groundwater — the risk of contamination
from fracking fluids is low. At the same time, he said, these requirements
are self-regulated by the oil and gas companies, and this, too, could be
an area of change down the road.
Carlson said he and others also want to further examine the foundation
effects of horizontal drilling and fracking.
“I can tell you, many oil and gas companies want to do the right things,”
Carlson said. “It just takes research and time to know how this can be
done in the most responsible manner.
“Can oil and gas industry do better than it is now? Absolutely. And that’s
what we’re working on.”