Devico Directional Drilling

The DeviDrill is a steerable wireline core barrel. The design of the N-size tool was introduced in 2001. Today it is successfully applied in various projects all over the world, from geotechnical investigations to the mining industry. The DeviDrill reduces the cost of exploration drilling programs by hitting targets quicker and more accurately than with traditional core drilling methods. By making multiple branches from a mother-hole, it dramatically reduces both the time spent and the cost, and, in addition, you get the geological information from wherever you want. No time is lost on moving the drill rig, drilling through the overburden, and drilling further down to where you almost were with your previous hole.

Total weight	87 kg / 192 lbs
Total length	5.4 m / 17.7 ft
Length front section	3.2 m / 10.5 ft
Weight front section	47 kg / 104 lbs
Length rear section	Length rear section
Weight rear section	23 kg / 51 lbs
Bit diameter	NWL
Reamer diameter	NWL
Reamer diameter	72.0 mm / 2.83”
Core diameter	31.5 mm / 1.24”
Core length	3 m / 9.8 ft
Length inner assembly	5.4 m / 17.7 ft
Weight inner assembly	17 kg / 37 lbs
Instrument barrel length	1.6 m / 5.2 ft
Instrument barrel diameter	51 mm / 2.01”
Pumping/latching unit	Longyear NQ™
Landing ring	Longyear NQ™
Landing indication	Yes
Core block indication	Yes
Pull out by-pass valve	Yes
Use of additives	Optional
Dogleg severity (DLS)	0-20º/30 m / 0-20º/100 ft
Operating pressure	20 bar + circulation pressure
Feeding force (max)	4500 kg / 9900 lbs
RPM	300-1200

Recommended parameters

Dogleg severity, NQ™ rods	9º pr. 30 m / 9º pr. 100 ft (180 m / 590 ft radius)
RPM	300 – 800
Feeding force (Bit weight + sliding force)	1500 – 2500 kg
Typical penetration rate	3 m/h / 10 ft/h
Typical production rate	9 – 27 m/12 h / 30 – 90 ft/12 h (50% – 75% of conventional wireline drilling)

Clients have reported time and cost savings of up to 80 percent in projects where the DeviDrill was used. A satisfied geologist stated: “Devico forced the hole down in inclination, and the 1000 meter deep hole switched from total failure to great success.” The DeviDrill uses a normal drill string and is fully compatible with the N-size wireline system. There is no need for additional water pumps, drill strings, or survey instruments. Devico’s survey tools are a fully integrated part of the tool, as they stay on board and measure while drilling. Coring during steering provides a complete record of the geology. It leaves nothing in the hole – except a bend. The curvature or dogleg can be adjusted from completely straight to more than 20 deg/30 meters. However, the recommended curvature from the drill rod manufacturer is 9 deg/30 meters, as any greater deviations will result in extensive wear on the drill rods.

How it works

The principle behind the tool is a drive shaft running through a bushing offset from the centre line of the tool. Expanding pads operated by a differential pressure is keeping the DeviDrill in a fixed toolface while drilling in a curve. The inner assembly carries an inner tube collecting the core, a muleshole system, and an instrument barrel with the survey tool recording inclination and tool orientation. Data is stored inside the tool and downloaded wirelessly to a PDA after each run. There is no need to trip drill rods in and out of the hole during directional coring, surveying and orientation, as this is all wireline operated. The DeviDrill has been proved to work well in both igneous and sedimentary rocks. Over time, Devico has gained much experience in how the DeviDrill behaves under different conditions, and possesses valuable information about directional planning and drilling. To ensure rapid and trouble-free implementation into your drilling program, directional ore drilling with the DeviDrill is offered as a service to our clients by highly trained and experienced Devico staff or selected qualified license users throughout the world.

FAQ

Do you get core samples in the directional core drilling sections? YES: A major difference between Devico’s DeviDrill directional core barrel and other directional drilling technologies is the ability to collect continuous core samples as the hole is being steered. The DeviDrill is an actual wireline core barrel, and in resemblance and use is more similar to a normal wireline core barrel than other directional drilling systems. The core sample means there is no risk of missing an ore zone, and directional drilling can be performed near, or even within, an ore body without the risk of missing information.FOR FURTHER INFORMATION: Click Here

When planning the construction of tunnels, rock caverns and shafts, an extensive investigation of the rock formation in the area is required. The investigation is used to identify problematic ground and secure an efficient and low-risk construction. Directional core drilling is an investigation method that allows core sampling along any defined trajectory, providing extremely accurate and relevant information about the rock formation near the planned underground construction.

• Continuous core sample and geological information from the planned tunnel trajectory.
• Data on the extent and orientation of problematic rock formations.
• Information about the mechanical properties of the rock formations.
• Basis to estimate groundwater inflow.
• Basis to estimate stabilization measures.
• Basis to estimate construction costs and duration.

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Where traditional core drilling (DHH-1 & 2) gives limited information, directional core drilling (DCD-1) penetrates the geological formations parallel to the planned tunnel.

By utilizing directional core drilling it is possible to steer the borehole along a predefined trajectory, no matter if it is curved or straight. With high accuracy the borehole will follow the specified path, for instance parallel to a planned tunnel, while at the same time collect a core sample over its full length. With this approach fault zones and fractures are drilled through in the same direction as the planned construction will hit them, giving relevant information about size, properties, material, leakage etc.

The borehole may be started at an available location near the planned underground construction and then steered as required to reach the direction and area of interest. When the borehole is in position the directional core barrel (DeviDrill) is pulled out of the hole and replaced with a standard wireline core barrel. This allows a full size core sample to be collected through the most interesting zones. Should the hole deviate, or if there is a turn in the planned trajectory, the standard core barrel will again be replaced with the DeviDrill, and the hole steered back to the desired path. The planned trajectory can be anything from straight to curve with a radius of as little as 200 m.

Before starting the borehole a tolerance corridor is defined, specifying the maximum distance the borehole should be from the planned trajectory at any time. The tolerances depend on the project requirements, but are of often set to approximately 1% of the borehole length. This means, for a 1000 m long hole, the core sample is from a location never more than 10 m away from the planned tunnel.

The core sample, both from the directional and standard drilling process, can be tested in a lab to reveal the mechanical properties of the rock. Further geophysical and hydrological tests can be performed in the completed borehole. Combined these tests will significantly improve the geological mapping and reduce the risk of surprises during construction. The benefits of directional core drilling is well documented, and since the start in 1988, Devico has participated in multiple international tunneling and underground construction projects. Several thousand meters have been drilled in countries like Norway, Sweden, USA, Australia, Hong Kong SAR, South Korea, and more.