HDD Rig

HDD Rigs in operation

With horizontal directional drilling rigs from Herrenknecht, pipelines and protective pipes can be installed under rivers and infrastructures quickly, cost-effectively and with minimal impact on the environment. Examples of pipeline applications include oil and gas, hydrogen and CO2, water and sewage, district heating, high-voltage power lines, cable bundles and much more.

HDD Rig types by pulling force

When selecting the size of an HDD rig, the required pulling force is decisive, which depends largely on the project parameters such as the length and diameter of the borehole to be created. Herrenknecht HDD rigs offer pulling forces between 45 and 500 tonnes and have power packs with outputs ranging from 285 to over 1,000 kilowatts (382 to over 1,340 hp).

Simple but functional

With HDD (Horizontal Directional Drilling), pipelines are installed in three steps. First, the HDD rig bores a pilot hole from the launch point toward the reception point. The rotating drill rods are precisely guided along the planned alignment by a surveying system directly behind the drill bit. During drilling, mud pumps convey a bentonite suspension directly to the nozzles attached un the drill bit. In soft geologies, the soil is excavated hydraulically at high pressure. In rock drilling, excavation is carried out mechanically using a mud motor. The bentonite mixes with the excavated material and flows back to the starting point through the annular gap between the drill rods and the borehole wall. A separation plant separates liquid and solid components from each other and returns the treated suspension to the bentonite circuit.

The pilot bore is followed in a second step by reaming. After exiting at the reception point, the pilot drill gear including the surveying system is removed and replaced by a reamer. With cutting tools and bentonite nozzles, the soil is removed both hydraulically and mechanically when the drill string is pulled back. The water-bentonite mixture supports the enlarged borehole, removes the soil and simultaneously cools all components. Reaming is usually performed in several passes until the final borehole diameter is achieved. This is about 30 to 50 percent larger than the pipeline diameter. In a third step, the pipeline is inserted. The prefabricated pipeline is connected to the drill string. Lifting the front end creates a so-called overbend and the entry angle of the pipeline is adjusted to the exit angle of the borehole. At the same time, falling below the minimum bending radius is prevented. Behind a reamer and a swivel joint, the pipeline is pulled back to the entry point by the HDD Rig to its final position. During this process, bentonite minimizes friction between the pipe casing and the soil.

Frame-Rig: Their low dead weight and ease of transport make Frame Rigs a reliable and cost-effective solution. Without its own transport system, the Frame Rig reaches the jobsite on a regular semi-trailer. A standard crane is sufficient for loading, unloading and alignment on the jobsite.

Trailer Rig: The HDD rig in trailer design with a 2-axle chassis is suitable for simple transportation as a semi-trailer. It can be coupled and uncoupled quickly and without additional auxiliary equipment. No crane is required for rig up and rig down. This flexibility makes trailer rigs particularly suitable for projects with multiple boreholes thanks to short transport and mobilization times.

Crawler Rig: Crawler Rigs offer significant advantages on jobsites in rough terrain not accessible for trucks or cranes. The robust and flexibly maneuverable caterpillar tracks allow full autonomous mobility and maneuverability in difficult terrain.

Modular Rig: To simplify transport to remote regions, modular rigs can be disassembled into two or three modules and transported in standardized containers. The modules are connected together on site using simple screw connections.

Compact Rig: Compact and maneuverable rig for smaller projects and inner-city applications. For shorter drill rods (range 1-6m/20ft), optionally equipped with an onboard cabin and a high-pressure mud pump, the rig can be used flexibly, especially in confined spaces.