Many of our previous blogs are about the importance of choosing the right core bit and the right core bit configuration. Recently I started discussing some of the reasons that core bits underperform, even if you have chosen the right ones. Some of the reasons involve changes in ground conditions or not using the best drilling parameters for the drilling project. One of the best ways to determine what is off is to examine the wear profile of your bit crown and change drilling parameters if necessary. An earlier blog looked at the problem of over exposed diamonds and this time we will look at core bits that are polished.
We’ve talked a lot in previous blogs about the importance of choosing the right core bit and the right core bit configuration, so I think it is time we talk about getting the most out of your core bit. 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 lack of experience. One of the best ways to determine what is off is to examine the wear profile of your bit crown and change drilling parameters if necessary.
Unless you hear from another driller who has already drilled in your zone, there is no way to tell if you will encounter a problem with water circulation. Some areas are notorious for having voids, fractured ground or underground rivers. These include Nevada and the western USA, as well as a large part of South America. Large geological faults that run through these areas are often to blame for the ground conditions.
No matter how carefully you planned and drilled, bore holes are rarely straight. Many things can have an effect on the direction of the hole, such as weight on bit, poorly set up drill rig, fractures or voids in the ground formation, bedding planes, or ground that goes from hard to soft. Too often, the path of the bore hole needs to be corrected in order to reach a desired target and that is when you should consider using a wedge.
A surefire way to stall operations and lower productivity is to break a drill rod in a bore hole – a too common occurrence in diamond drilling.
A rod string can break, either from too much pressure or by being dropped, or the bit can melt and fuse to the rock. Certain ground conditions can lead to your equipment being jammed. Clay can swell enormously when water is introduced and this swelling can trap the rod and drill bit. Coming across sand can also be harmful as the sand can collapse around the drilling equipment.
Getting the longest life possible for your core bit is key if you want to run a productive and profitable drilling operation. Changing a drill bit takes time especially the farther down the hole it is, and the time spent replacing a bit is not useful.
Different soil conditions present different challenges for diamond drilling. As we have said often, choosing the right core bit for the type of ground in which you are drilling is an important decision. Non-stable and abrasive ground such as sand, gravel, or ground with pebbles and cobbles can be found in mineral exploration as well as in geotechnical drilling operations.
Making sure your drill rods are in good condition is a good way to keep drilling operations productive. Drillers need to get in the habit of checking drill rods before using them. There are 5 common problems that can affect drill rods so let’s look at what causes these problems and how to fix them.
Topics: Tips on common drilling issues
Sharpening a bit is also known as stripping. There is no easy, one-size-fits-all solution to sharpening a bit. It takes experience and knowledge. It is also something that technicians are often asked about, so in this blog I provide a few suggestions and basic guidelines.
In diamond drilling, vibration in the bore hole is sometimes unavoidable since rotating tools and equipment are being used, but drillers want to keep vibration to a minimum. In-hole vibration can cause premature damage to the bit, the core barrel, the drill rod and other machine components. Excessive vibration can have a detrimental effect on core recovery. All of these will increase your operational costs. A variety of things can cause excessive vibration in your bore hole.
Topics: Tips on common drilling issues