Directional Core Drilling for Mineral Exploration
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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 world wide.
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.
Overview: Coring While Steering
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 (DCD) is done with the DeviDrill directional core barrel.
The principle behind the DeviDrill is a drive shaft running through a bushing offset from the center line of the tool. Expanding pads operated by differential pressure keep the DeviDrill in a fixed orientation while drilling in a curve.
The inner assembly carries an inner tube collecting the core, a muleshoe system, and an instrument barrel with the survey tool recording inclination and tool orientation.
Orientation data is stored inside the tool and downloaded to a PDA after each run.
Bit diameter 75.4 mm/2.97” (N-size)
Reamer diameter 75.6 mm/2.98”
Core diameter 31.5 mm/1.24”
Core length 3 m/10 ft