VMOS: What the Río Negro crossing involves, the technique used by Techint-SACDE, and what comes next for the project

The strategic crossing beneath the Río Negro marks one of the most technically demanding milestones in the construction of the Vaca Muerta Oil Sur (VMOS) pipeline, the most significant privately developed piece of energy infrastructure in Argentina in recent decades.

With the project surpassing 51% overall completion by mid-January 2026, this operation — launched in the first weeks of the year — represents the decisive step toward seamlessly linking shale oil production from the Neuquén Basin with the export terminal at Punta Colorada, on Argentina’s Atlantic coast.

The method being used is horizontal directional drilling (HDD), a high-precision trenchless technique that allows pipelines to be installed underground across major obstacles — such as rivers, highways or canals — without open-cut excavation or visible surface disturbance. In the case of VMOS, the crossing is carried out at an approximate depth of 30 meters (about 98 feet) below the riverbed, minimizing any impact on water flow, water quality and productive activities tied to the Río Negro, one of northern Patagonia’s key water resources.

The HDD technique is executed in three main stages:

1. Pilot drilling: From an entry point on the north or south bank, depending on the design, an initial small-diameter bore (typically 15 to 30 centimeters) is drilled using a directional drilling head. The head incorporates sensors and navigation systems — such as magnetic probes or gyroscopic tools — allowing operators to adjust the trajectory in real time, following a pre-calculated curved profile that descends beneath the river and rises on the opposite bank. Drilling fluid, a mixture of bentonite and water, is used to lubricate and cool the tool, stabilize the borehole walls and carry excavated cuttings to the surface.
2. Reaming: Once the pilot bore emerges on the opposite side, the drilling head is replaced with a reamer of progressively larger diameter. The reamer is pulled back through the pilot hole, enlarging the tunnel to the diameter required to accommodate the 30-inch (76.2-centimeter) pipeline. In long crossings such as this one, multiple reaming passes may be required to reach the final diameter without compromising ground stability.
3. Pipe insertion, or pull-back: Finally, the preassembled and welded pipe section — in this case, already hydraulically tested on the south bank — is connected to the reamer and pulled through the enlarged tunnel from the exit side toward the entry side. Drilling fluid continues to reduce friction and prevent collapse. Once in place, the pipe is stabilized, tied into the rest of the line and subjected to final integrity tests.

At VMOS, the Techint-SACDE joint venture is applying international standards for this crossing — one of 22 special crossings planned along the route, of which 76 have already been completed in total — to ensure long-term structural integrity and operational safety. The operation is carried out from both banks: preparatory work and pilot drilling advance on the north side, while the pipe section on the south side stands ready for insertion.

This milestone is critical for the project schedule. With the mainline installation along the 437-kilometer (271-mile) route already completed — including the final automatic weld in November 2025 — attention is now focused on segmented hydrostatic testing, installation of the four planned pumping stations, 28 block valves, and construction of the marine terminal at Punta Colorada.

Pumping stations are critical elements of the system, as they compensate for pressure losses from friction and elevation changes along the pipeline, ensuring a steady and safe flow of crude oil. The design includes:

• Allen Head Station (origin point, in Neuquén/Río Negro): Acts as the link between Vaca Muerta production and existing pipeline networks, such as Oleoductos del Valle. It includes storage tanks — several with capacities of 50,000 to 55,000 cubic meters each — and has already posted significant progress in civil works, welding, electrical foundations, piping and auxiliary systems, including fire protection, drainage and operational offices. Some reports show progress exceeding 20%, consolidating its role as a strategic hub.
• Pumping Station 1 (PS1) in Chelforó, in the Middle Valley of Río Negro province: Progress includes civil works, a transformer station, precast foundations, cable trays, electrical gantries and technical building foundations.
• Pumping Station 2: Located in or near Santa Rosa, with construction scheduled to begin in the first quarter of 2026.
• Pumping Station 3: Planned for the Somuncurá Plateau area, around kilometer 349 of the pipeline, also slated to start in the first quarter of 2026.

These facilities will initially support throughput of 180,000 to 390,000 barrels per day, depending on the phase, with full pressure and flow monitoring. The design is scalable: future expansions, potentially including additional stations, could raise capacity to 550,000 to 690,000 barrels per day, and up to about 700,000 bpd.

Start-up of the first phase — with an initial capacity of 180,000 bpd — remains scheduled for late 2026, with ramp-up to 390,000 to 550,000 bpd in 2027 and a technical ceiling of up to 720,000 bpd.

Strategically, successfully completing the Río Negro crossing strengthens VMOS as the logistics corridor that will eliminate current bottlenecks and position Argentina as a relevant net exporter of light, unconventional crude.

With pipe-laying finished, work continues on completing hydrostatic tests, finishing crossings, installing valves and pumping stations, and accelerating the buildout of storage tanks and infrastructure at the Punta Colorada terminal. The goal is for the first exports from the San Matías Gulf to begin in early 2027.