Geoprobe® 7822DT Installs Geothermal Loops

During the last 23 years, Tony Poulter, vice president and co-owner of RAZEK in Louisburg, Kansas, has operated a Geoprobe^® machine. And it seemed to him the second question he was asked every day was, “How deep can that thing go?” And the answer has always been, “until we hit rock or run out of rods!” Poulter said. “Of course the first question was, 'Y’all drillin’ for oil?'."

The answer to both questions has now become more complicated for Poulter and the company. 

Poulter attempted to drill a 6-inch boring to 150 feet for the installation of geothermal loops at their headquarters in Kansas. They spent time researching whether they could even attempt rock drilling with their 7822DT, and many experts told them they were foolish to even try. According to Poulter, “they said rock drilling must be done with a larger rig with more weight, more torque, and higher rotation speed.” But, as Poulter found out, the 7822DT outperformed all of the ‘experts’ and created a very lucrative niche market for their firm.

Direct push refusal at the property is around 8 feet, and at 12 feet they encountered clay overburden with intermittent layers of weathered limestone and some shale. During the first 30 minutes of air rotary drilling with the 7822DT, they passed 50 feet and felt “very confident,” Poulter said. Limestone bedrock was encountered around 80 feet, and the drilling rate slowed. As they advanced deeper into the boring, and the rock became tougher to penetrate, the 7822DT never slowed down. 

“We passed 100 feet at the 90-minute mark and ended up at 162-feet below ground surface, just 3.5 hours after beginning (give or take a few breaks along the way), ” Poulter said. “We could have kept drilling deeper but, as history has proven, we could only go until we ran out of rods!”

They drilled 6-inch diameter borings to install 15 geothermal loops at their facility to upgrade the company’s furnace and air conditioning systems for ground source geothermal heating and cooling.

Tripping out in 5-foot increments was no small task, but the hydraulic break-out system worked flawlessly on every joint.