Sonic drilling technology is often desirable-sometimes even specifically requested in government contracts-because of the necessity of a nonintrusive drilling option for sensitive projects, such as dam remediation, nuclear site investigations and hazardous waste-site reclamation.
Vibrations from sonic drilling are not transmitted very far beyond the drill, allowing for drilling in vulnerable areas, including critical eco-systems, unstable terrain or situations where traditional drilling would be harmful or impossible. Here is a small sampling of the many projects where drillers found this technology to be beneficial.
Upgrading the New York Subway System
Closing off two of five lanes on 11th Avenue in bustling downtown Manhattan to drill more than 200 freeze-holes as part of a subway system upgrade wasn’t the biggest problem facing Keith Myers and Joe Sopko of Layne Christensen.
Even the material being drilled-a bedrock valley below overburden-wasn’t an issue. The real problem was avoiding the myriad gas, water, telephone, sewer, fiber optics and other service lines in the top 10-15 feet of the two-block area.
Sopko, director of engineering from Layne Christensen’s operation at Fort Washington, Wis., says drilling double and compound angles was troublesome considering the large number of utilities in the top 15 feet.
For this project, Layne Christensen workers retrofitted the sonic drill heads onto a couple older rigs the company had, providing the delicate touch needed to thread carefully through the service lines.
Sopko says such a job would have been impossible without the sonic drill heads.
Unlocking the Arctic’s Best-Kept Secret
Decades ago, huge natural gas deposits were discovered in the Mackenzie Delta area, northwest of Inuvik in Canada’s beautiful frozen western Arctic. As it turned out, proving out the estimated 1.8 trillion cubic feet of recoverable natural gas reserves underneath Parson’s Lake was no easy feat of logistics and endurance as temperatures dipped to minus 40 and winds howled across the lake’s frozen surface.
To ensure the protection of the lake, ConocoPhillips, the company tasked with the difficult job of proving the reserve, chose a sonic drill-the only drill type able to bore quickly through wet clay without using drilling mud and without disrupting the sensitive lake environment.
Positioned on ice more than 6.5 feet thick and huddled inside a protective rig cover, the crews of Sonic Drilling worked 24 hours a day, carefully drilling through ice, water and lake bottom before continuing through a mixture of sand, wet clay, silt and gravel to depths of 150-240 feet.
The results were successful. Crews were able to gather important data, core samples and proof of the gas reserves while, just as importantly, meeting all environmental regulations and sparing the unique arctic aquatic world around the drillers from any human-caused damage.
Dam Remediation Takes Gentle Approach
Miller Drilling has been using sonic drill heads manufactured by the Sonic Drill Corporation since the late 1990s. Today, Miller Drilling remains in high demand because of sonic drilling advantages.
Shane Hughes, sales director for Miller Drilling, says his company has sonic rigs throughout the country, and while many people are concerned about hydro-fracturing or getting high-pressure air into the formation, they are impressed by the sonic drills’ ability to drill dry, causing little intrusion, particularly in dam remediation.
Miller Drilling has worked on two of the largest dam remediation sites in the United States using sonic rigs. With four sonic drill rigs constantly in use, Hughes says it all comes down to geology.
A sonic rig, he says, is capable by itself of getting through things that would require several conventional methods to get through.
The Mississippi area, home to some of the rarest, coarsest silica sand in the world, presents its share of challenges to drillers.
“The sonic gives the ability to drill all types of soils in the same hole without a lot of trouble,” says Daryl Karasch, a sonic drilling foreman for Traut Wells and a seasoned Mississippi driller.
Karasch says Traut Wells has had a 100 percent recovery rate even when encountering sands, clays, shale, sandstones and limestone all in the same hole. The quality of core samples is what makes sonic drilling so successful, and Karasch says his sonic drill rig has often outperformed other rigs by a three-to-one margin on the sites he’s worked.
On one Mississippi site where a sonic drill was finally called in, seven other companies had already tried and failed to produce the needed results. The area’s famous silica sand was no match for a sonic, however, Karasch says.
Glacier Secrets Revealed
Motivated by a desire to teach and learn, Dan Kelleher and Ken Borrell of the Midwest Geosciences group drove 20 hours from their home city of Waverly, Minn., to the University of Calgary in Calgary, Alberta, to experience their first sonic borehole in Canada.
Midwest Geo was offering one of its workshops on glacial successions for more than 50 geologists from Canada and the United States. The course teaches the principles of sedimentary depositions, the effects of sedimentary weathering and the methods to describe those elements on boring logs.
“The sonic drill was awesome,” says Kelleher, a hydrogeologist and project manager with Midwest Geo and co-founder of the company. “It’s the answer this industry needs so badly. The word really needs to get out about what these rigs can do.” ND