HORIZONTAL

RAISE BORING

Topics

Overview of methods and technology

Common aplications

Project-specific experiences

Hitting the target

Raiseboring concept

The pilot hole is (normally) drilled down to a lower level, diameter 250 – 310mm

A reamer with a larger diameter than the pilot hole is attached to the drill string

The pilot hole is then reamed to the final diameter

Raiseboring equipment

Drillsite

Tri-cone pilot bit and drill pipe (drill string)

Stabilizers

Bit Reamer Stabilizer

Six-Rib Stabilizer

Reamer, cutter and cutter

housing (saddle)

Technology and methods

The raiseboring machine provides thrust and rotation for crushing the rock

During pilot hole drilling, the materials (cuttings) are removed by flushing water through the hollow core (4 ¾”) of the drill string, forcing them out the annular space between the drill string and the rock wall

During reaming, the materials fall by gravity, or are flushed out with water on horizontal/low angle holes or mecanical scraper

The raiseboring method is only for use in rock, hard or soft

Equipment Capacities

Our company’s machines can drill up to 600 meters (+)

We have reamer sizes from 440 mm to 3100 mm

Machines can be set up to drill in any angle, from vertical to horizontal

Our machines can be dissassembled and transported by helicopter

Equipment is heavy: drill string weighs 200 kg/meter, machine from 9 - 13 tonnes,

”Blind hole” drilled for nuclear storage facility

Nuclear power station, Aspo

Oscarshamn, Sweden.Horizontal tunnel for deposit of

nuclear waste.

Inclination: 1,8 grader

Diameter: 1,8 meter

Length: 95 meter and 15 meter

The drifts are situated 220 m

below the surface.

Project site without road accessSauda Hydro Power Project, Istjønna.L=410m Ø=1060mm Inclination=2%

Drilling river intakes for small hydro power projects

Directional guidance to hit the target

Advanced survey instruments are used to track the position of the pilot hole

By using special drill pipes (stabilizers), regulating thrust and rotation, and amount of bailing water, the vertical direction of the pilot hole can be controlled to minimize deviation from the target

Horizontal deviation cannot be controlled when using traditional raise boring equipment. Deviations of 0-2% of the length can be experienced.

Combination of drilled tunnel and D&B tunnel:

Pilot hole is completed before D&B tunnel, pilot hole location is surveyed, and D&B tunnel direction is adjusted to meet the pilot hole

Directional drilling…?

If the target requirements are very stringent, the pilot hole can be drilled with a directional drilling system

Different methods

Directional core drilling, that is in turn reamed to larger diameter

Use of mud motor with bent sub (North-Sea drilling)

Advanced stabilizers

Stringent target requirements adds significant costs and completion times to the project:

Pilot hole is drilled in several steps

More than one drill rig

Success of any directional drilling method is dependent on rock type, hardness, stratification, weak zones, etc.

More economical to have less stringent target requirements

Landfall, Faroe Island

Pilot hole drilling

Shore Aproach/Landfall Faroe Island

Reaming Process

Removal of cuttings/muck disposal methods

Water flushing with high pressure pump

Flow: 2000-5000 l/min, system pressure: 20bar.

Scraper system.

Auger system

Drilled Landfall from a rock tunnel into the North Sea, Norway

Location: Karstø area at the coast of Norway

Project: Oil pipeline from Åsgard oil field in the North Sea, to Kårstø Refinery

Client: Statoil

Drilling contractor: Entreprenørservice AS, Norway

Drilling equipment: Indau R90H, raise boring machine

Reaming head: Sandvik ø 1600 mm

The drilling operation: Time consumtion: 6 weeks.

Drilled Landfall from a rock tunnel into the North Sea, Norway

Drilled Landfall from a rock tunnel into the North Sea, Norway

Drilled Landfall from a rock tunnel into the North Sea, Norway

Horizontal, Drilling, Skien, NorwayØ2,44m, L= 42m

Flesland Airport and Hammerfest water supply

Flesland Airport

Runway Runway

L= 480m

Ø1800mm

Hammerfest, Water supply Water reservoar

L=390m

Ø660mm

Why use raiseboring for small tunnel projects?

Environmentaly Friendly

Little or no visible impact during and after drilling operations

”Tailored” cross-sectional area of tunnels, no over-break

Smooth tunnel walls; low surface roughness (<5 mm)

Rock support (anchor bolts, concrete lining) inside tunnel is rarely needed, circular tunnels are inherently stable

Road access to drill site not necessary

Safe and clean working environment for the operators (no fumes, dust)

Clean water only is used for removal of cuttings. Water can be recycled by using on-site settlement basins/containers

Very little noise from the equipment (electrically/hydraulically driven)

Environmentaly friendly…

Summary

The raise boring method is well suited for drilling water tunnels for small power projects

”Tailored” cross-sectional area, little or no need for rock support

Low surface roughness

Environmentaly friendly, very little visible impact, little noise and dust during construction

Customized equipment and experienced crew can drill tunnels in most conditions

Equipment can be transported to sites with no road access