In our last blog, we looked at the expression “pushing a block”, what it meant and why drillers should never try to advance in a hole when the core is blocked. However, in many parts of the world, especially where dry hole drilling is common, or when the hole is very deep, different advice and procedures should be followed. We are going to look at these different situations and the recommended procedures.
Bore hole deviation is one of those things that occur despite all the preventative measures and precautions that diamond drillers may take. Deviations may occur due to equipment that is lost and stuck in the bore hole or it may be intentional because the geologist has requested a new trajectory. A deflection wedge is one of the oldest and simplest ways to steer the bore hole. There are other choices for directional drilling and you can read about them in this blog.
Our technical team in Northern Ontario had an interesting request a while ago during an onsite visit. The mining company they were visiting was a longtime customer with multiple mines. The mine was one of the largest in the world and a large player in the area. With a lot business already done, and an excellent relationship developed over 25 years, the customer would often consult with us when it came to anything to do with coring challenges. During this particular visit, they asked if we could come up with a procedure and the necessary tooling to be able to get core using unconventional drill rigs such as a jumbo drill or a bolter.
It has been a while since we did a blog on matrix troubleshooting where we examine the different wear patterns on a bit crown. By looking at the wear profile, you can get clues as to why your core bit may be underperforming. There are many variables that can cause a really good core bit to underperform. It can be a change in ground conditions, drilling parameter or simply a lack of experience.
Drilling parameters are really important when it comes to drillers achieving great drilling performance and long bit life. They help guide a driller avoid burning bits or damaging other drilling equipment. Diamond drillers have learned that there is a relationship between the drilling parameters and all others factors in drilling, such as the diameter of the equipment of you’re using, rock hardness or ground variability.
In a previous blog, we discussed some of the issues you encounter when drilling in soft rock. This time, we’ll look at the opposite end of the spectrum: hard rock. Hard rock is defined as being over 6 on the Mohs scale of hardness. Common types of hard rock included kimberlite, granite, chert, quartz and silicified rock.
Drilling in soft rock is not always a walk in the park. Oftentimes, we associate hard rock as the type of ground that is most difficult to drill in. This is true, and we will address those issues in an upcoming blog. However, soft rock as its own set of challenges. Let’s look at soft rock and how you can avoid problems and be more productive.
It’s kind of inevitable that, like death and taxes, you will have to deal with borehole deviation at some point in your drilling career. Bore holes are rarely straight and the further down you go, the more likely the chance of your hole going off the chosen trajectory. This can be quite a problem if the geologist needs to hit a particular ore body. And the fact of the matter is that many of the ore deposits near the surface have already been depleted so you need to drill deeper.
Let’s face it, core recovery is what it’s all about in diamond drilling – it’s the reason we are out there on a drill site. The more core that you are putting in the box, the happier your boss or the mining company will be. Not surprisingly, this is a topic that our field technicians get asked about a lot and that our subscribers say is a challenge. Read more about improving core recovery here.
At least up here in the Northern hemisphere, winter has arrived in full force. In many regions, the coldest temperatures over consecutive days were recorded, breaking many previous records. The experts say that extreme temperatures are likely to continue.