AKK River Niger Crossing: HDD Equipment & Technology behind the crossing.

Completing a major pipeline river crossing requires more than a powerful drilling rig. The equipment, drilling method and supporting systems must be suited to the crossing length, pipeline diameter and geological conditions beneath the ground.

This was particularly important during the Ajaokuta–Kaduna–Kano (AKK) Gas Pipeline River Niger crossing, where a 40-inch gas pipeline had to be installed along a 1,565-metre underground route through mixed sand, gravel and rock formations. The crossing presented significant engineering challenges because of its length, pipeline diameter and changing ground conditions.

PCE Nigeria was contracted to execute the crossing using high-capacity Horizontal Directional Drilling (HDD) equipment, dual-rig intersecting technology, synchronous reaming and a specially developed drilling-fluid formulation. The project provides a practical example of how drilling equipment and coordinated engineering are used during long-distance pipeline installation.

The AKK River Niger crossing presented several construction requirements that influenced equipment selection. At 1,565 metres, the crossing required drilling equipment capable of operating across a substantial underground distance, while the 40-inch pipeline needed a sufficiently large borehole to accommodate the pipe during pullback.

Geological conditions introduced further complexity because the underground drilling route passed through sand, gravel and rock formations. Each material behaves differently during drilling, affecting cutting resistance, borehole stability and the removal of excavated material.

Loose sand and gravel can make borehole conditions difficult to maintain, while rock formations require suitable drilling tools and effective cuttings removal. Equipment selection therefore had to account for more than pipeline diameter and crossing length, including drilling torque, pulling capacity, borehole enlargement, guidance requirements and drilling-fluid circulation.

We addressed these requirements through a coordinated HDD equipment configuration supported by specialist drilling methods and technical systems.

For the AKK River Niger crossing, we deployed high-capacity HDD equipment, including a 1,200-ton-class drilling rig supported by a 350-ton rig. The larger rig provided substantial pulling capability for the crossing, while the supporting rig enabled drilling operations from the opposite side of the river.

This configuration was important because long-distance HDD construction places significant demands on drilling equipment. As crossing length and borehole diameter increase, engineers must account for drilling resistance, equipment loads and the forces involved in pipeline installation.

A high-capacity rig provides the pulling capability needed for demanding drilling and pullback operations, but successful installation also depends on maintaining suitable borehole conditions and controlling the drilling process. The supporting rig enabled coordinated operations from both sides of the crossing.

Rather than relying on one rig to perform every operation independently, we used a dual-rig arrangement for the pilot-hole drilling and reaming activities required for the installation.

One of the key technologies used on the AKK River Niger crossing was dual-rig intersecting technology. In a conventional HDD operation, a pilot hole is generally drilled from one side of the crossing towards the other.

Dual-rig intersecting technology uses a different approach, with drilling operations conducted from opposite sides of the crossing and the pilot-hole paths guided towards an underground intersection.

Once the paths are connected, they establish a continuous underground route for subsequent drilling and pipeline installation activities. For the AKK project, we used this method to construct the pilot hole along the planned 1,565-metre crossing.

The operation required specialist guidance systems, accurate drilling alignment and close coordination between the teams operating from both riverbanks. Maintaining the planned underground route was particularly important because the crossing passed through different geological formations.

Completing the pilot hole was only the first major stage of the underground installation. Before the 40-inch pipeline could be pulled through the crossing, the borehole needed to be enlarged to provide sufficient clearance.

This process is known as reaming, which involves using specialist cutting equipment to enlarge the pilot hole to the required diameter. Depending on the borehole size and ground conditions, enlargement may be completed through multiple stages.

For the AKK River Niger crossing, we used dual-rig synchronous reaming, coordinating operations from both sides of the river during borehole enlargement. The process required careful management of drilling forces, tool performance and cuttings removal.

Different formations created different demands. Sand and gravel required attention to borehole stability, while rock formations introduced greater cutting resistance and the need for suitable reaming tools. Drilling-fluid circulation was also important for transporting excavated material out of the borehole.

The objective was to prepare an underground opening suitable for the large-diameter pipeline while maintaining manageable borehole conditions.

Accurate borehole guidance is essential during long-distance HDD construction. Engineers must monitor the drilling assembly's position and direction to keep the pilot hole within the planned alignment.

This becomes particularly demanding when drilling operations are carried out from opposite sides of a crossing, as the drilling paths must be accurately guided towards their intended underground connection.

We incorporated specialist guidance systems and coordinated field operations into our AKK construction methodology to support the alignment control required for pilot-hole drilling beneath the River Niger.

Accurate guidance also helps establish suitable borehole geometry for subsequent reaming and pipeline pullback. The AKK project illustrates why guidance technology must be considered alongside drilling-rig capacity and other equipment requirements.

Alongside the drilling rigs, reamers and guidance systems, drilling-fluid management played an important role in the AKK crossing. During Horizontal Directional Drilling, drilling fluid helps transport excavated soil and rock towards the surface, support borehole stability, cool and lubricate drilling tools, and reduce friction.

These functions are particularly important when drilling through mixed geological formations over long distances. For the AKK crossing, we developed a specialist drilling-fluid formulation suited to the sand, gravel and rock conditions encountered along the route.

A typical HDD drilling-fluid system requires mixing equipment, circulation pumps and solids-control equipment to prepare, circulate and manage the fluid. Its properties must be monitored as drilling progresses because cuttings, groundwater and changing formations can affect performance.

Inadequate fluid management can contribute to cuttings accumulation, increased drilling resistance and unstable borehole conditions. This is why drilling-fluid engineering must be considered alongside drilling equipment, reaming operations and borehole design.

Bentonite is commonly used as a primary component of HDD drilling fluid, helping develop viscosity and filtration-control properties. At PCE Nigeria, our Brighter Star product range includes BRSBENT SQ activated Bentonite and specialist additives for different drilling conditions.

After the borehole had been enlarged and conditioned, the prepared pipeline could be installed through the underground route. This final installation stage is known as pipeline pullback.

For a large-diameter pipeline, pullback requires careful planning because the pipe must travel through the borehole while remaining within its allowable installation limits. Engineers consider factors including pipeline weight, borehole geometry, friction, bending radius and anticipated pulling forces.

The drilling equipment must provide suitable pulling capacity, while the borehole must remain sufficiently stable and clear for installation. Pipeline preparation is also important, with fabrication, welding, inspection, coating protection and the working space needed to position the pipeline all requiring consideration before pullback.

During installation, drilling-fluid management and controlled pulling operations help manage resistance and reduce the likelihood of pipeline damage. For the AKK crossing, installation of the 40-inch pipeline completed the underground section beneath the River Niger.

The completed crossing connected an important section of the wider AKK Gas Pipeline route. Further project details are available on the AKK River Niger crossing project page.

Our experience on the AKK River Niger crossing offers several practical considerations for engineers and pipeline developers planning complex HDD installations.

1. Equipment Capacity Must Match the Crossing Requirements

Pipeline diameter, crossing length, borehole geometry and anticipated drilling forces all influence equipment selection. High-capacity rigs are important for demanding installations, but equipment capacity must be assessed alongside the overall construction method. A powerful rig alone cannot compensate for unsuitable borehole conditions or an ineffective drilling strategy.

2. Drilling Methods Influence Equipment Configuration

The use of dual-rig intersecting technology requires drilling equipment and personnel to operate from opposite sides of a crossing. This creates additional requirements for guidance, communication and coordination. Equipment must therefore be selected not only for its individual capacity but also for its role within the planned construction methodology.

3. Ground Conditions Determine Tooling Requirements

Sand, gravel and rock formations create different drilling and reaming challenges. Suitable drill bits, reamers and supporting systems must be selected according to the expected geological conditions. Where formations change along the route, drilling teams must be prepared to monitor performance and respond appropriately.

4. Drilling-Fluid Systems Are Essential Supporting Equipment

Drilling-fluid mixing, pumping and circulation systems are an important part of HDD construction. Their capacity and performance must support borehole stability, cuttings transport and the requirements of the drilling operation. The AKK crossing illustrates why drilling-fluid engineering should be considered alongside drilling-rig selection.

5. Equipment and Field Operations Must Work Together

Complex HDD crossings involve several interconnected stages, including pilot-hole drilling, reaming, borehole conditioning and pipeline pullback. Decisions made during one stage can influence the next.

Coordinated engineering and field execution help ensure that equipment, personnel and construction activities support the planned installation. These principles apply to river crossings and other long-distance pipeline installations beneath roads, railway lines and similar obstacles.

We completed the AKK River Niger crossing on 26 July 2025, installing the 40-inch gas pipeline along the 1,565-metre underground route.

The project involved high-capacity HDD equipment, dual-rig intersecting technology, synchronous reaming and a specially developed drilling-fluid system, all selected to meet the requirements of the crossing.

Following the AKK project, PCE Nigeria was subsequently contracted to execute the OB3 River Niger crossing, involving a larger 48-inch pipeline along an approximately 2,000-metre underground route.

The experience from these crossings highlights the importance of selecting equipment and construction methods according to the conditions of each project. Rig capacity, drilling tools, guidance systems and fluid circulation must be considered together because each contributes to the installation process.

What equipment was used for the AKK River Niger crossing?

We deployed high-capacity HDD rigs, supported by specialist drilling guidance, reaming equipment and drilling-fluid systems. The project used a dual-rig configuration for pilot-hole drilling and synchronous reaming.

What is dual-rig intersecting technology?

Dual-rig intersecting technology is an HDD method in which drilling operations take place from opposite sides of a crossing. The drilling paths are guided to intersect underground, establishing a continuous pilot-hole route for subsequent borehole enlargement and pipeline installation.

Why was synchronous reaming used on the AKK project?

Synchronous reaming formed part of our method for enlarging the underground borehole to accommodate the 40-inch gas pipeline. It involved coordinated drilling operations from both sides of the crossing.

Why was drilling fluid important during the AKK crossing?

The crossing passed through sand, gravel and rock formations. Drilling fluid helped transport excavated material, support borehole stability, lubricate drilling equipment and maintain suitable conditions during construction.

How long was the AKK River Niger HDD crossing?

The AKK River Niger crossing extended 1,565 metres and involved installing a 40-inch gas pipeline beneath the waterway.

When did we complete the AKK River Niger crossing?

We completed the HDD installation on 26 July 2025, following the commencement of crossing work on 25 March 2025.

The AKK River Niger crossing shows how equipment selection, drilling methods and field operations influence the delivery of a complex pipeline installation. The drilling rigs provided the required capacity, while guidance, reaming and drilling-fluid systems supported the different stages of construction.

Our work on the crossing brought these elements together to complete the underground installation. At PCE Nigeria, our services also include specialist HDD engineering and construction, pipeline EPC, drilling-fluid solutions, equipment resources and technical support for infrastructure projects across Nigeria.

Planning a major HDD river crossing or complex pipeline installation?

Explore our HDD and pipeline construction capabilities or view the AKK River Niger crossing project for more information.

Project and equipment enquiries: wanyang@pcenigeria.com