Directional drilling enables the drilling of curved boreholes, which make it possible to hit a specific target with high precision, but also to intercept multiple targets by branching out from the same mother hole. In mining, directional drilling is thus proven to be a cost-effective and often less environmentally harmful method of drilling. This guide provides an overview of the basics of this drilling practice in different industries, while also discussing the benefits of directional drilling in mining.
What is directional drilling?
Though reservoirs are accessible vertically, directional drilling offers an alternative when there are certain objects in the way to reach the target. By drilling at an angle, the operator can access the target and is able to explore more parts of it since reservoirs tend to form horizontally, not vertically.
Directional drilling techniques have been in use since the 1920s. It offered a new solution to challenges accessing the material beneath the surface. Conventional drilling for oil and gas, mining, and infrastructure goes down in a straight line, meaning that all components of the drilling process, including the drill bit and drill string, go vertically into the ground. With emerging technology, the necessary angles and controlled trajectories were made possible by directional drilling. These technologies have made their way from the oil and gas sector into the mining sector and have undergone considerable improvements in recent years. For that reason, directional drilling is more precise and customizable than ever before.
Understanding when directional drilling is useful
Directional drilling offers a solution for when a direct vertical approach is not feasible. Directional drilling makes it possible to steer the drill underground and control the path away from the structures. When steering the path of the drill, operators can ensure that it goes down, curves, goes sideways, and drills horizontally for a long distance.
It is utilized in various industries, such as:
Mining sector
Oil and gas
Infrastructure
Mining sector
Mining companies use directional drilling when they want to reduce the total number of drilled meters for a multi-target drilling program. As a technique, directional drilling is highly efficient and precise when one is tasked with drilling huge areas. It is also extensively used in geotechnical drilling, which requires an even greater degree of accuracy. In the drilling, one follows specific paths, for which directional drilling bores enable.
Oil and gas industry
Directional drilling is a technique used by oil-extraction companies that want to access oil in underground reservoirs. Most traditional, vertical oil wells are positioned above the targeted reservoir, but there are many oil and gas projects where it is not possible to drill vertically into the ground. There might be structures blocking the way or environmentally sensitive rock formations that one does not want to intrude upon. This puts limitations on how one can and should drill for the natural resources that are of interest.
Infrastructure
For installing infrastructure like pipelines and cables, directional drilling is a valuable construction method. If there are roads, rivers, or any obstacles underground, directional drilling makes it possible to escape, cross, and avoid them with precision and efficiency.
Why to use directional drilling in mining projects
If there is a tight budget
If the budget is tight or one simply wants to ensure high levels of profitability in the project, directional drilling offers a solution. By drilling directionally, the number of drilled metres will be reduced. This can save costs on exploration budgets by reducing time spent on actual drilling. Thus, it increases the likelihood of carrying out a financially lucrative project.
For precise targeting
Directional drilling is highly precise, and thanks to the emergence of new technology, it has become possible to target boreholes more efficiently than before. In mining, the use of downhole or mud motors have been made obsolete thanks to technologies like the Azidrill, which enables one to reduce the number of drill holes. In effect, this reduces the total drilling distance and the time and financial resources required to carry out the operation.
To get an increased exposure to the ore body
It is quite common to work around irregular ore bodies when mining. More times than not, minerals are not settled in a single deposit, but accessible in separate pockets that are not joined together. For example, ore bodies that are located close to environmentally sensitive areas will impact the accessibility of the target. To work around this, the drill is positioned from an angle and steered towards one pocket at a time. Directional drilling increases the exposed section length through the body by drilling through it at an angle.
What does the process of directional drilling look like?
When drilling directionally, the drill bit is guided along a non-vertical path, while the bit itself is rotating. The key to today’s advanced borehole steering technology is the trajectory control. Trajectory control relies on coordination between surface and downhole equipment. Surface equipment provides power to rotate the entire drill string, while specialized downhole equipment executes the steering.
Benefits of directional drilling
It limits the environmental impact of drilling: Compared to conventional drilling, there is a reduced soil disturbance and ecological impact on sensitive habitats surrounding the reservoir. By limiting the construction footprint, it ensures that wetlands and forests are not unnecessarily impacted. Mineral exploration can also be done with less disruptions to residents in the area.
It is cost effective: Directional drilling allows companies to explore smaller areas (one location), but still explore multiple underground targets. Reducing the number of drilling locations can have an impact on the costs. Unlike vertical drilling, which requires several rigs, directional drilling can access a considerably large area from a single rig.
It is time-efficient: When working from one rig, the time it takes to drill is minimized since one reservoir or multiple zones can be targeted by a single directional wellbore. Additionally, a single drilling pad can host several directional wells while targeting different reservoirs.
The emergence of new technology
Historically, directional drilling and horizontal drilling have been slower than vertical drilling. The need to stop regularly and take time-consuming surveys prolonged the work. In oil and gas exploitation and mining exploration, downhole motors have historically been used in both directional drilling and horizontal drilling. Today, directional drillers rely primarily on steerable mud motors with bent housings and subs when drilling in oil and gas projects. This progress has made the drilling process for oil and gas much more efficient and reliable.
Directional core drilling replaces downhole motors in mining
As for the mining sector, emerging technologies are competing with the downhole motors and are in effect making them obsolete when exploring minerals. Directional core drilling is a technology that competes with the downhole motors. It makes the steering tools more feasible to use in combination with mining equipment. For instance, the Azidrill technology replaces the dependence on downhole motors in the mining industry.
Directional drilling summarized
Directional drilling is a drilling technique that is used to drill well along non-vertical paths. It has been practised since the 1920s, but in recent years, there has been much technological progress in the field. These modern advancements have made it possible to drill precisely in a large variety of different projects. This requires specialized equipment and meticulous planning, which is accomplished with advanced geological models and softwares.