Underground Construction - September 2019 - 34

Directional Drilling

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
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SEPTEMBER 2019 | UConOnline.com

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

http://www.deltadirectional.com http://www.americanaugers.com http://www.strikeusa.com http://www.volvoce.com http://www.UConOnline.com

Underground Construction - September 2019

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