Deep Rock Drilling Achieved to Aid Geothermal Studies

When it comes to deep rock drilling jobs with tough geologies, Tony Warren with Hawkston LLC opts for his Geoprobe^® 3230DT with 6-speed head.

“We do air hammering and do it all with the Geoprobe^® 3230DT 6-speed head,” Warren said. “I prefer it when doing deep holes.”

So when Duke University needed deep rock drilling completed as part of their class project conducting geothermal studies, he knew the 3230DT was up for the challenge.

“The first time we drilled 360-370 feet. The second time we went to 670 feet,” Warren said. “We’re going back to do six to eight holes, 1200-feet each.”

To achieve the 670 feet, they augured to 30 feet, then cored through using mud rotary for the next 30 to 60 feet and set casing. They then set up an independent Moyno using an auxiliary hydraulic pump to core through volcanic granite and metamorphic rock from 60 to 670 feet.

“The colors are just beautiful,” Warren said. “Lots of people don’t core volcanic granite ever. I’ve been doing this 36 years and it’s the first time I ever have.”

He admits many doubted whether the 3230DT could complete the 670 feet.

“The 6-speed head on the 3230DT has more power and cores smoothly. You have more control over the down speed and water pressure,” Warren said. “The rig is just incredible, makes it so nice to work when coring rock.”

To Warren, the pressure adjustment is key when deep rock drilling.

“The ability to adjust the water pressure, head feed, RPMs. Most guys won’t go past 100 feet, but you can easily,” Warren said. “The friction was the only thing that stopped us from going deeper, so we’re going to eliminate the friction when we do the 1200-foot holes.”

Since this was for a geothermal studies class project, they would shut down drilling for an hour or two each day to review with the students what they were doing.

“It was great being involved with that kind of job where they’re doing geothermal studies to run a whole campus the size of Duke on geothermal energy,” Warren said. “It’s awesome.”