June 2020 Vol. 75 No. 6


Unique Intersect Bore Features Surface Tie-In

By Jeff Griffin, Senior Editor

Drilling two pilot holes that meet and connect between the two starting points always makes an interesting horizontal directional drilling (HDD) story. 

Often, intersect installations are made to cross a body of water, and the connection is made underground, then the product pipe is pulled through from one end of the bore hole.

A recent project in Texas took a different approach: the intersect connection to install a 30-inch steel pipe was made on the surface of the water in Nueces Bay, an extension of Corpus Christi Bay. The project owner was Nustar Energy.

“The span across the bay was about 16,000 feet,” said Cory Baker, general manager of Hard Rock Directional Drilling. “We used two rigs, each drilling 7,500 feet. Both rigs punched out in the bay. We left about 1,000 feet in the middle for the two punch outs to be tied in.”

While drilling was underway, a trench line was dredged out of the bottom of the bay. Crew members working from barges pulled each section of pipe into the water, which floated because of the pipe’s buoyancy. Ends of pipe that would be placed in the dredged trench were coated with concrete and required floats to prevent them from sinking. Connections were made while pipes floated in the water.

“Once pipes were connected,” said Baker, “we pulled back on each end to lower the connected pipe into the dredged ditch line, which then was backfilled. This is a short, simple description of what was a very complex installation.”

Hard Rock worked with Nustar from the conception of this project to its completion. Marine support was provided by Orion Marine Group.

Unique procedure

Making an intersect on the surface is unusual. This was, perhaps, one of the first instances the procedure was utilized.

“In the beginning,” Baker said, “we looked at doing the project with a single drill. Running all the calculations, we found that pulling in 15,000 feet of 30-inch pipe would be pushing the limits of pulling capabilities and would require support of additional equipment. In addition, it was not possible to lay out the entire 15,000 feet of pipe for a pull-in.

“We considered many options and concluded the safest and most constructible was to do two drills into the bay and pull both back in, allowing the connection to be made above the water. Once the tie-in was made, we pulled back on both ends of the pipe to lower the line into the dredged ditch in the bottom of the channel, which was then backfilled.”

Tennessee Pipeline performed the above-water welds, and Orion backfilled the dredged trench.

A Vermeer D1000x900 drilling unit with 1 million pounds of pullback, and maximum torque of 102,500 foot-pounds was used on each side of the bay. Each used an 8-inch NOV mud motor with a 12¾-inch bit and Brownlee Gyro tracking system. Support equipment was the same for each drill rig and included a Vermeer R9 fluid reclaimer and Tulsa Rig Iron 660 mud pump.

Baker said both pilot bores were challenging with unusual ground conditions.

“Geotech exploration gave us a good idea of what we would encounter under the bay,” Baker explained, “but we found a larger amount of petrified wood than expected. This was very odd and a challenge, but we got through it. I’ve kept several pieces of the wood to use as paper weights in my office.”

The presence of the petrified wood also caused concern about the coating on the pipe, so for added protection, a Scar-Guard wrap was applied to the pipe before installation.

To open the pilot holes, three ream passes were made with 24-, 36-, and 48-inch reamers. A final pass was made with a 36-inch swab.


To prepare for product installation, pipe strings were laid out and welded on land, then pulled into the bay and staged in the water using multiple barges.

“When it came time to pull the pipe into the drilled hole,” Baker continued, “there was not room in the bay for it to lay straight. For the pipe to be in one section, it had to have a large horizontal curve in it. It was a challenge to hold the pipe in place while pullback operations were in progress. Personnel on barges kept the pipe in place and from straightening out.”

WHC Energy Services provided rig support on the north side and Tennessee Pipeline did the same on south.

Looking back, Baker said scheduling played an important part in successfully completing the project.

“We had both drills going at the same time,” Baker said, “so this meant two marine support operations going at the same time in close proximity to each other. We had to keep safety and communication at the forefront.

“There was no way to pull both drills at the same time, so we had to stagger the start dates for each drill to insure we did not have a conflict. We also did not want a large amount of time between pulls because we knew we had to pull on both ends of the product to lower it into the trench after the tie-in. This is why timing and scheduling was very important.”

An additional complication was Hurricane Barry being in the Gulf at the time operations were underway.

“The storm was pulling water out of the bay, making it difficult to float the product pipe in the shallow water,” he said.

The project was completed in 90 days.

“We are pleased to have been a part of this project,” Baker concluded. “Its success can be credited to the teamwork of all involved: Nustar Energy, Hard Rock, WHC, Tennessee Pipeline, and Orion.”

Baker praised the efforts of the entire Hard Rock team that included Chris Jones, vice president of business development; Tom Forconi, maxi rig division manager; Leo Aguirre, assistant division manager; Rig 1 Crew Leader Mario Diaz; Rig 2 Crew Leader Rafa Gamez; and their crew members.

Based in San Antonio, Texas, Hard Rock is experienced in all types of directional drilling and specializes in long, difficult water crossings and intersects of large-diameter pipes. •


Hard Rock

Tennessee Pipeline

WHC Energy Services




Tulsa Rig Iron


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