Devico Directional Drilling

Directional Core 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.


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

Directional Core Drilling for Mineral Exploration

Save Time, Money and Metres

Directional Core Drilling allows controlled deviation of the borehole path and/or multiple branches from a parent hole, saving the cost, effort and uncertainty involved in multiple single holes. If your project needs multiple planned drill holes or accurate planned trajectories then DCD may be a cost effective and efficient solution. DEVICO offers a DCD rental package to clients using highly skilled and experienced technicians worldwide.


There are many benefits using DCD in your exploration project. A few of them are listed here.

    Compared to standard wireline drilling (re-drilling from surface)
  • Reduced drilling length
  • Less wear on drilling equipment
  • Fewer drill sites
  • Less environmental impact
  • Full control over natural deviation
  • Improved borehole accuracy

    Compared to other directional drilling techniques
  • Core in directional sections
  • Low water consumption
  • All necessary equipment in small start package
  • Fits directly on N-size drill string
  • High penetration rate in hard rocks
  • Easily adjustable dogleg
  • Higher dogleg used due to smoother curve
  • Drill string rotation also during steering
  • Directional surveys performed at hole bottom (through DeviDrill bit)
  • Full size N-size borehole and no additional reaming required.
    The Devico Directional Core Drilling (DCD) service includes:
  • Free borehole planning.
  • Free savings analysis.
  • DCD to branch boreholes and control natural deviation.
  • Reporting and plotting borehole progress.
  • Reaching targets within 1 % error.
  • Field technicians controlling the DCD, ensuring high quality results.
  • Strong on-site collaboration leading to efficient operation.
  • Assistance in monitoring core orientation and surveying boreholes.


Core drilling for minerals normally consists of drilling long sections in bedrock before reaching the ore horizon, making the process more time consuming and expensive than necessary. In addition, natural deviation can change the drill path and reduce the value of the information gained from the borehole. With Devico technology, you can complete a drilling program quicker, and with higher accuracy than with traditional core drilling methods. The Devico technology makes it possible to control borehole deviation and steer the hole accurately towards the target, while also collecting core samples during the steering process. When the first hole is finalized, it can be sidetracked and used again to steer towards a second target. Sidetracking means a new hole is started from within the old, often several hundred meters below surface. With this approach, there is no need to move the drill rig to a new site and re-drill the top section-collecting core from rock formations of no value. The sidetracking is quickly performed by cutting straight in a curved section of the first hole. By using this method, no wedges or cement plugs are necessary. Making several branch holes will significantly reduce the length of a drilling program, which can lead to remarkable savings in both time and money. As less drill sites are required, the environmental impact of the drilling program is also reduced.


Directional core drilling is delivered as a service where Devico supply the DeviDrill directional core barrel, borehole survey tools and field technicians that controls the directional drilling operation. To provide top qualified DCD services to the drilling industry Devico and its subsidiaries have established an international group of expert field technicians that work on directional projects around the globe. Our technicians are highly educated and have been through an extensive training period of one year or more to earn their title. On DCD projects, they work together with the drilling contractor to secure that the operation runs smoothly and efficiently. The technicians also work with the project geologists to prepare and optimize drilling plans. They will recommend the depth where directional drilling should be started, and calculate the length of steering necessary to aim the hole towards the target.

Directional Core Drilling for
Tunneling & Geotechnical Investigation

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.


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.