Rigonomics: Modern HDD Contractor Tools For Drilling Rock

By Jeff Griffin, Senior Editor | June 2011 Vol. 66 No. 6

One project near Pittsburgh, PA, required drilling 2,200 feet of approximately 18,000-pound psi rock to install 24-inch diameter steel casing for multiple HDPE gas transmission and water lines. An American Augers DD220 was used for the pilot hole and first reaming pass that was equipped with a 6 ¾-inch Adtech mud motor with an 8 1/2-inch sealed bearing tri-cone bit and multiple low-torque Sharewell hole openers of 22 to 36 inches to complete the opening of the hole. An AA DD440 was used for the final reaming pass and pulling in the pipe.

“Most of our projects are more complex and not ordinary in overall scope,” said Hockran. “Recently we completed a project in Pennsylvania in a moderate-hard shale formation that required an innovative approach to fluid management. A frac-out created the need to drill a vertical intersect to our drilled hole and provide a controlled path for the drilling fluids. This was successfully achieved and provided significant advantages for both the drilling process and most importantly, the environmental impact to a nearby stream.”

Laney Directional Drilling
For more the 21 years, Laney Directional Drilling, Humble, TX, has been completing long, difficult horizontal directional drilling installations, many in rock.

About 20 percent of the company’s projects involve rock, estimates Grady Bell, Laney vice president of business development. Many of the company’s rock projects have been notable (see page ?? of this issue for a report about mountain HDD installations through rock that Laney recently completed in Colorado’s Mesa Verde National Park).

Indeed, Laney is equipped to take on any rock projects that come along with 11 Laney-designed and built drill rigs, the smallest with 300,000 pounds of pullback, plus recycling systems, mud motors and all the support equipment necessary.

Alan Snider, P.E., Laney vice president of engineering, said most HDD projects containing rock that are put out for bids typically have rock under 25,000 psi unconfined compressive strength. However, he added, there have been crossings designed and successfully constructed with unconfined compressive strengths in excess of 40,000 psi.

“Planning is critical for drilling through rock,” said Snider. “Accurate geotechnical information is needed to properly plan and prepare for a project.”

Last month, Laney transported equipment, including the company’s 1.7 million-pound pullback drill rig, to West Virginia to start four crossings ranging from 1,500 to 3,300 feet to install segments of a 24-inch steel gas pipeline.