Sonic is something a lot of drillers talk about, particularly in environmental and geotechnical. To find out more about the technology and practical applications in those areas of drilling and beyond, National Driller recently spoke with Fred Hafner, U.S. operations manager for sonic at Boart Longyear. Our interview here is edited for space and clarity.
Q. What are the advantages of sonic, versus other methods of drilling?
A. The number one advantage for utilizing sonic is a continuous sample, which is anywhere from 3 inches in diameter to 9 inches in diameter. It provides a continuous core of what you are drilling in, so you see everything that is sitting below grade.
Q. What are its limitations?
A. The limitations are depth. Sonic technology is going to do about 700 to 900 feet. It’s limited to the material you can drill. Although it is capable of drilling into bedrock, the machine was designed to drill in overburden material. So, if you have a lot of bedrock drilling, there are other methods that are better.
Q. Boart Longyear just released a new sonic rig, the LS250 MiniSonic. What was the decision process for developing this particular rig?
A. Boart Longyear has been making a mini sonic drill for probably close to 10 years. This LS250 MiniSonic is 10 years of research and development, trial and error out in the field, and this drill is designed to go out in the marketplace.
Q. What are some of the key features of this new rig?
A. Number one: If a customer is interested in sonic drilling, they’re looking for the sample. It’s a relatively undisturbed core sample. It’s highly accurate for everything you penetrate. You see the stories of previous drilling with other applications, the stories … about how they missed a fine change in material. … For sonic, again, it’s highly accurate with an undisturbed core that picks that up. You get to see how the lithology is laid out underground almost perfectly once you bring the sample up to surface. It’s a method that provides straight holes with minimum deviation.
A lot of methods, where you’re focusing on bit pressure, a lot of times the hole will walk off, as they say. With sonic, with its casing set up, it has minimal deviation. Sonic drilling has an inner core barrel and an outer casing. The only waste you have, for the most part, is what you bring up out of the core barrel, which is the sample. You’re not using a mud. You’re not using any water. So you have less waste. The only waste you’re dealing with is the sample, which is really the key reason why you’ve used sonic in the first place. Other methods like auger drilling, you have cuttings to dispose of. With rotary, you have cuttings and fluid and drill mud to dispose of. Compared to other overburden drilling methods, like rotary and auger, it’s much faster and much cleaner.
Q. If I work for a drilling services company and make buying decisions, why would I choose an LS250 over another sonic rig?
A. Over the last 20 years, sonic technology has really taken off. The key driver for anyone owning a drilling company that does environmental, geotechnical, shallow mine services, they’re going to be asked by the customer for a sonic drill. If they’re not being asked now, it’s coming, because the demand has grown 1,000 percent over the last 20 years. You either have this machine, or you’re going to be out of the market.
Boart is the industry leader with sonic drilling. Over the years, they’ve operated more sonic drills than anyone globally. This rig, this 250 — and I am a fan of the MiniSonic drill — is the result of 10 years of real-life field trial and error. We put these drills out doing projects for customers, paying contracts, and over the 10 years they’ve worked out the little bugs … that you’ll have with just about any drill. So this rig coming out on the market, it is user-friendly and it’s built around the driller and it’s built around the customer. You have all the safety mechanisms in place. People want a compact drill, and as far as the power goes and the size of this drill, you really can’t find anything else out there. It has a rod handler, which keeps the rod handling by a human being to a minimum. It’s a hydraulic rod handler that adds the rods to the drill head, so it’s less wear and tear on the body, and it’s a lot safer.
Q. Boart Longyear worked with the LS250 for several years before deciding to release it publicly. Did the rig evolve over that time working in-house? In what ways?
A. Over those 10 years, the little things that drive you crazy about a drill, they’ve been taken care of. A real obvious one was, when this drill first came out they didn’t have a rotation barrier on them. That was something the customer had asked for. So these rotation barriers were built with field mechanics and our engineering staff, and trial and error with the size of the rotation barrier and how to make that work, not only while you’re drilling but also while you’re transporting it. That was something that was directly driven from the drilling business. ... I know my operators down here fielded a lot of calls from the engineering team, and met in person anytime we were changing something within the head. It was a group effort to try to design something that was going to work.
I think it’s important to mention that it wasn’t 10 years of one drill out in the field. It was 10 years of 25, 40 of these drills out there — different designs, different styles, different operators, different geological conditions. We ran these worldwide. That’s a whole lot of feedback and real field testing to put this model out there. Boart Longyear was patient with getting this out there. They didn’t rush something into the market. In fact, if anything, they were probably a little cautious about it. They definitely wanted to put a product out there that they can stand behind. You’ve got a certain amount of responsibility when you put something out there that has the name Boart Longyear.
Q. Let’s talk about the jobsite. Tell me about a project or two where, for Boart Longyear crews, the LS250 was the solution to a jobsite problem.
A. They are numerous. So the drill is small, light and compact. We put these drills on barges, and we drilled over the water on shallow waters on smaller barges. That’s the big plus of this drill, is its size. A larger drill, and its ancillary equipment, creates the need for a larger drill path. This compact drill and the way it’s designed with its rod handler, the client, the customer doesn’t have to spend as much money preparing a drill path. It’s much smaller. It’s got a very low ground pressure — it’s 4 psi. So it can get into fragile and sensitive areas. … It’s just small, compact, quick and easy to set up. It’s very, very efficient. We’ve put it on sensitive environmental areas where you don’t really want a large drill. We’ve had it inside buildings where you don’t have the room to get a large piece of equipment in. We’ve had it on active leach pads. And again, a big drill is going to have issues getting into and out of the area because of its weight. There’s going to be a lot of disturbance. With this drill, there’s relatively less ground disturbance.
Q. Sonic drilling is often written off as expensive. How does the LS250 address that from a contractor perspective?
A. This is what I can tell you: This has become a customer requirement. I have seen this in requests for proposals’ scope of works, where sonic technology is specifically being asked for. If you don’t have this rig, you’re not in that market. This is an entry-level drill, and I’m sure the price is much lower than the full size drill. If you want to start to get into it, this is a good way to start off.
The head on this drill is pretty compact. ... The last head that we replaced on a MiniSonic rig lasted three years — 36 months, almost to the day. So it is a durable rig. My suggestion for someone wanting to get into it, is to work with Boart Longyear. I know that they offer some training if it’s something that you’re willing to put the time into. (Ed. note: At the time of this interview, Boart Longyear was working on developing training to complement sales and leases of the LS250.) All of our operators, at one point, were driller assistants that had no drilling experience. But with time and patience, teaching them, not biting off more than you can chew, doing the right projects, it’s something that anybody can pick up.
Q. Who is the ideal customer for the LS250?
A. Anybody that plays in the environmental market. Anywhere where there is shallow groundwater concerned. This drill, I think, is rated for 250 feet. I’m not positive about that depth, but that is the depth that we’ve had our MiniSonic rigs to. Again, because of its size, being a compact rig, and being able to go to those kinds of depths — to be able to drill through boulders and cobbles, rough drilling conditions that are difficult to go through with auger rigs, and if you want to eliminate a drilling fluid because you are trying to minimize the waste that you dispose of on an environmental site — this is that drill. If you’re in that market — environmental and geotechnical — this is the drill. This will replace your auger rig, this will replace your units such as that where waste is a concern. Setting a good, clean monitoring well — this is your wheelhouse.