Laney Innovates Shore Approach for Direct Pipe
In its most basic description, the Valley Crossing Pipeline Project helped to provide natural gas to millions of customers in Mexico via a link-up in the Gulf of Mexico. When describing how and what this project actually accomplished, is a different story.
The project established new levels of innovation and records for a relatively new trenchless installation method — Direct Pipe — in a small segment of 168-mile project to transport natural gas from Texas to a state-owned utility in Mexico. Direct Pipe made its North American debut in 2010.
Let’s take stock of what resulted from this $14.2 million project.
The Valley Crossing Pipeline Project (VCP) became the first successful shore approach in North America using the Direct Pipe installation method; Installed by Laney Directional Drilling, this incredible project also set a new world record for the total length of a Direct Pipe project at 4,900 ft. This installation outdistanced Laney’s previous Direct Pipe record in North America, which was 3,505 ft, as well as the world record in Lochem, Netherlands at a length of 4,590 ft.
Additionally, this project was the first use of Laney Directional Drilling’s new, one-of-a-kind Derrick Direct Pipe Cleaning System with a 300-bbl mixing tank and centrifuge — designed for the outfall execution offering full fluids circulation and lower pressure for minimal environmental risk in the soft soil conditions beneath the Texas shoreline.
This project necessitated tremendous planning, preparation and confidence as project crews dealt with a variety of challenging factors, including the project’s remoteness, as well as a healthy hurricane season and a prolonged period of working in a confined space.
VCP, owned by Enbridge and Valley Crossing Pipeline LLC, was constructed to transport reliable supplies of clean burning natural gas to the CFE — Mexico’s state-owned utility, serving approximately 37 million customers — to provide natural gas transportation services to meet Mexico’s growing electric generation needs, as well as to other shippers at delivery points in South Texas. This additional access to vital supplies of clean burning natural gas will promote economic development along the project route and in the region.
A portion of this project necessitated an installation solution to interface the onshore segment at the Texas border to the offshore segment in the Gulf of Mexico. Originally designed as a horizontal directional drilling (HDD) project, the decision by the project owners was made to, instead, use the Direct Pipe method. Using Direct Pipe, Laney crews tunneled 4,900 ft from Clark Island in Cameron County, Texas, and then thrust an additional 1, 350 ft of pipe offshore so that the 42-in. steel pipe could be picked up in the Gulf and connected to the Mexico project link.
The product pipe for the project consisted of 42-in. OD, with 1,25-in. wall thickness and API-5L x70 steel pipe with fusion-bonded epoxy and an abrasion-resistant overlay. Extensive matting was required for the entry setup and for the pipe to be strung out over the marshlands of south Texas.
“With this distance and pipe size, it had never been done before,” says Laney vice president of operations Rob Hotz. “We were learning as we were going. It was definitely an interesting one.”
The Clark Island location is just a few miles north of the Mexico border and the jobsite was remote and extremely difficult to access. “There was no infrastructure in the area and we were right next to Boca Chica State Park and South Bayl,” says Hotz. “Everything had to be accessed each day through barges — all the equipment, materials and personnel — and transported over water to docks constructed on [Clark Island] where we worked from.”
With any installation that pushes the limits of what has previously been accomplished, there are numerous challenges throughout design, project planning and construction. The decision to go with Direct Pipe vs. HDD was made early. With HDD, were concerns with the geometry of the preliminary drill and the location of the breakthrough of the pipeline into the Gulf of Mexico. The option of using the Direct Pipe method alleviated those concerns, as well provided a much more cost-efficient construction method for project owners. Using Direct Pipe also lowers annular pressure acting on the surrounding subsurface formation, thereby reducing the risk of inadvertent returns.
Direct Pipe combines two proven trenchless methods: microtunneling and HDD. Unlike HDD, Direct Pipe uses a microtunneling boring machine (MTBM) and instead of being a multi-step install process, it’s a single step. The benefits over microtunneling is that there are no deep shafts for launching and installing a pipe section. The pipe is welded prior to installation.
For this particular project, using Direct Pipe was the right solution. “Direct Pipe benefited this project due to the minimum frac-out risk vs. HDD in these environmentally sensitive conditions,” says Gerhard Lang, business development manager at Herrenknecht AG – Utility Tunneling Division. “The Direct Pipe technology is primarily considered when HDD is not applicable or the geological and hydrological conditions indicate too-high-of-a-risk for HDD.”
Hotz further explains that the marine support used on the project would have been significantly more challenging, costly and time-consuming using HDD. Laney worked extensively with Herrenknecht to implement an execution plan with the correct equipment design. Laney utilized a custom-built Herrenknecht HK750PT thruster and clamp with a Herrenknecht AVN 1000TBM, along its custom-built Derrick Direct Pipe Cleaning System that allowed crews to achieve proper returns throughout the project. Finally, the umbilical system was modified to a longer length, along with the internal confined entry setup.
Project mobilization started in mid-September 2017, delayed for a period after Hurricane Harvey made landfall the week that the project was initially scheduled to mobilize. Crews, working 24/7 for the entirety of the project, began tunneling in early November 2017, with the MTBM surfacing in the Gulf of Mexico on Dec. 2. Laney crews thrust the additional 1,350 ft of pipe through the tunnel to enable the offshore barge to pick up and layaway through the Gulf. After demobilization, crews were off location in early January 2018.
The project was completed on time and within budget.
This was the first project that Laney utilized its custom-built cleaning system. Hotz notes that one of the biggest challenges on a tunneling project is removal of spoils, which are then recycled and reused. “We have to get the spoils out of the fluid and recycle it, sending back downhole to keep [the project]going,” he says. “Otherwise, if we can’t keep up with our fluids and we have to stop forward progress, we are no longer making production. This system, allows us to maintain penetration and hole cleaning abilities so we can maintain production and forward progress.”
Hotz explains that the cleaning system is a closed loop system that is injected at the cutting head. “We’re sucking it back in at the same location after it’s mixed with the materials and we’ve pumped it through internal hoses back into the pipe and back to the surface to recycle it. We then send it back down for reuse.”
Jobsite safety was challenging at various stages of project construction. One area in particular dealt with the extended periods crewmembers spent in the pipe and the confined space entry safety measures put into place to protect them. Crews are sent into the pipeline using an electric cart and rail systems when required to perform verification surveys of the steering components in the head.
“There were nine confined entries for this project,” Hotz says. “And depending on far in the ground we are in the tunnel, they can be every 500 to 1,000 ft, depending on the situation. Once we start tunneling and got the MTBM in the ground, we worked 24/7 in two shifts.”
The Laney team planned extensively for entry during the initial connection of the MTBM and at the end during the machine’s removal from the pipeline. Laney also anticipated unplanned scenarios, from common repairs to mechanical and electrical fails. “Of the nine confined entries, the furthest entry was at a length of nearly 4,000 ft into the pipeline,” Hotz says. “All entries were made safely without negative results or safety breakdowns.”
Working on a remote location on a water crossing is also tricky. Hotz notes that on any given day, depending on which the wind was blowing and the high tides, the work areas would be inundated with water and unusable, forcing crews to regroup and use the other dock.
This project marked Laney’s 11th Direct Pipe installation since it added this trenchless method to its toolbox of installation methods. This project gives Laney the record for total pipeline installed via Direct Pipe in North America with 23,000 ft.
“We’re absolutely so excited about having this project selected as the Project of the Year,” Hotz says. “It was a great achievement for us and for Direct Pipe. We’ve had a lot of success with Direct Pipe where HDD just wasn’t the right answer. We know it ‘s not going to be a replacement for HDD. But where it makes sense, we’re excited that we have this tool at our disposal to meet clients’ needs.”
Project Owner: Enbridge and Valley Crossing Pipeline LLC
Engineer: Laney Directional Drilling
Contractor: Strike LLC (general), Laney Directional Drilling (sub)
Mfg./Suppliers: Herrenknecht, Derrick Corp.
Value of Trenchless Project (US$): $14.2 million
Sharon M. Bueno is managing editor of Trenchless Technology and a contributing editor to North American Oil & Gas Pipelines.