September 2019 Vol. 74 No. 8

Features

Though Challenging, HDD Intersect Project is Effective Solution

Jeff Griffin | Senior Editor

 

Directionally drilled intersects – two drill units drilling pilot holes from opposite ends of a planned bore path that intersect – are not unusual today, but hardly could be described as routine. The complexities of an intersect and consequences of failure deter most horizontal directional drilling (HDD) contractors from entering this highly specialized market.

Mississippi contractor Delta Directional recently completed a 5,826-foot intersect in McMullen County, Texas, south of San Antonio and northwest of Corpus Christi. Many intersects cross rivers and other bodies of water, and this one did, too, but most of the bore path was under wetlands that could not support heavy equipment used for open-cut construction.

Delta made the HDD installation for Strike, a pipeline, facilities and energy infrastructure provider. Strike is Delta’s parent company. The HDD segment of 42-inch steel pipe is part of a pipeline that will transport natural gas.

“We did cross the Nueces River and Old Nueces River channel,” said Billy “Blue” Cleveland, Delta Directional president. “That comprised about 500 feet of the job with the remaining on right-of-way through two large cattle ranches that were designated wetland areas. The drill locations for both rigs were over three miles from public roads, so access was critical for the HDD equipment and personnel.”

Intersect conditions

Because of soil conditions, it was determined that an intersect was the best way to proceed, rather than a single bore. Bore paths were in difficult conditions that included hard shale, sticky clay and gravel. Depth was approximately 120 feet under the river bottom.

Two drill rigs were used: an American Augers pullback DD-1100RS with 1.1 million pounds of pullback and 108,000 foot-pounds of torque, and an American Augers DD-440 trailer- mounted drill rig with 440,000 pounds of pullback and 60,000 foot-pounds of torque.

The bore was launched by the larger machine set up on a 300- by 300-foot matted wood pad. The pilot bore was drilled with an HT 8-inch mud motor, 12¼ mill tooth bit and utilized a DataTraX Azimuth while rotating the tool. Support equipment included two MCD1000 cleaning systems, Lynx centrifuge, American Augers P750 pump and a Weatherford T425 tri-plex pump.

The second drill rig was set up at the exit end of the projected bore, also on a 300- by 300-foot pad and using the same components while rotating, as the first drill. Support equipment included one MCD1000 cleaning system, Lynx centrifuge, Weatherford T425 tri-plex pump, and F500 tri-plex pump.

“The intersect point was projected to be 2,800 feet from the exit-side rig and 3,026 feet from the entry-side rig,” said Cleveland. “The large machine started boring first, and the exit-side machine began drilling while the other bore was underway.”

The two pilot bores were completed in 23 days, single shifting.

“The intersect was completed on the first try,” he said. “Once it had been made, the larger machine pushed through the pilot hole to the exit side for the pullback. While drilling was under way, the 42-inch pipe was laid out on right-of-way through open ranch land and welded into a single 5,826-foot string weighing 1.8 million pounds on the rollers.

“The pilot hole was enlarged with Delta designed and engineered 36- and 60-inch hard-formation wing cutters. Pullback was completed in just 42 hours.”

Project challenges

Cleveland said challenges specific to this project were preventing inadvertent returns to the surface and turning large cutters in the sticky formations and gravel layers. “To complete,” he added, “we used environmentally safe additives to control the torque and water loss.”

Twenty-eight Delta employees worked 24 hours a day to complete the project.

“Planning, incredible teamwork, and assist from our parent company, Strike, contributed to the success of this project,” he said.

Cleveland also credited the performance of the two American Augers drill rigs and assistance of American Augers personnel. He again emphasized the critical importance of planning to achieve a successful HDD intersect.

A relatively small number of drilling contractors are making intersect installations. Cleveland estimates there are fewer than
20 actively involved in the market today.

“The common belief is an intersect is done because of the long distance of an installation,” he explained. “But there are many reasons that it can be the best option. A good example is a bore route that requires a lot of curves or high-degree curves. An intersect can eliminate some of the potential problems that occur under these conditions.”

Delta has been making intersects since 2001, and Cleveland tells an interesting story about the first one the company made.

Based in Newton, Miss., Delta Directional is a leader in the HDD industry, specializing in difficult projects and working in environmentally sensitive areas and hard rock. Delta has completed crossing with pipe sizes from 2 to 48 inches and in rock formations exceeding 57,000 psi.

Delta also is active in telecommunications construction and fiber installations, placing 4 to 5 million feet of cable in the ground each year.

Delta Directional’s HDD fleet contains 37 machines, 11 with more than 100,000 pounds of pullback, and the company has
276 employees working on HDD projects.


FOR MORE INFORMATION:

Delta Directional, (601) 683-0879, deltadirectional.com

American Augers, (800) 324-4930, americanaugers.com

Strike, (888) 353-1444, strikeusa.com

Volvo, (717) 532-9181, volvoce.com

Related Articles

From Archive

Comments

{{ error }}
{{ comment.comment.Name }} • {{ comment.timeAgo }}
{{ comment.comment.Text }}