Typically, manufacturing sonic drill rods is a three-piece construction process in which the rod ends are friction- or slip-fit and welded onto a mid-body. This allows manufacturers to use lower grades of steel in the mid-body to save on costs.

Boart Longyear utilizes an upset forging process in manufacturing its sonic drill rods. Upset forging refers to the process in which a drill rod begins its life as one single piece of high-grade steel tubing and is internally forged to ½” thickness on the thread ends which transitions to ¼” mid-body wall thickness. This eliminates welding the thread ends onto the mid-body, creating a significantly stronger one-piece-design sonic drill rod. 

At a high-level, the six manufacturing steps for sonic drill rods are:

1. Begin with high-grade steel tubing having 3 ½” outer diameter and ¼” wall thickness
2. Upset forge the rod ends to 9” in length and ½” wall thickness
3. Stress relieve the entire rod (heat and cool slowly)
4. Heat treat the rod pin and box ends (quench and temper) for strength and durability
5. Machine the pin and box tapered threads into the upset forged ends
6. Heat treat the pin thread a second time to a slightly higher hardness (increases life, prevents galling (rods seizing up into each other during drilling) and increases wear resistance)

This process, which draws on our vast experience manufacturing diamond coring rod, creates a 3 ½” outer diameter rod which has a 3” inner diameter mid-body and 2 ½” inner diameter thread ends. The rod ends are ½” wall thickness to 9” in length, while the mid-body is ¼” wall thickness, keeping the rod relatively light but extremely durable.

When you need the best and most efficient sonic tooling, look no further than Boart Longyear. High-quality precision steel plus special heat treatment processes provide unsurpassed stability, straightness, and durability of the sonic drill string assembly. Stringent manufacturing standards and ISO certification make sonic tooling from Boart Longyear the right choice for every sonic drilling project.

Contact your local Boart Longyear representative or distributor today.

Quality Policy:

Boart Longyear is committed to providing quality products, innovative solutions, exceptional service and value to our customers while meeting or exceeding all customers’ safety, environmental and regulatory requirements.

Following the advancement of the inner drill pipe and core barrel, the outer drill casing is advanced to within one foot of the leading edge of the core barrel.

The outer casing serves the same purpose as for conventional dual-line drilling systems by holding the borehole open for well installation, geophysical logging or other down-hole activities. Depending on drilling formations, drilling fluid may be introduced during the advancement of the outer drill casing.

Sonic drilling also greatly reduces the risk of project failure due to unknown or difficult subsurface conditions. It also offers the flexibility of advancing a temporary outer casing as the borehole is drilled, meaning more can be accomplished with a single borehole.

Although adoption of the technology has been slow, sonic drilling is now being seen as the solution for a variety of needs. In Canadian oil fields, for example, where soft rock formations predominate, companies are increasingly coming to recognize sonic’s advantages over both conventional rotary drills and auger drills for many applications.

After the 2014 failure of the Mount Polley tailings dam in British Columbia, the provincial government mandated the installation of monitoring wells and piezometers on tailing piles throughout the province. The difficult accessibility of many sites and the potential instability of the pilings made Boart Longyear’s new LS250 MiniSonic rig an obvious choice for the job.

The reliable, compact sonic rig is proving to be the ideal solution for a wide range of applications, including geotechnical, environmental, water and mining. Its compact size allows it to be easily transported to hard-to-reach sites like the tailing piles or to work in tight spaces.

Such was the case in downtown Calgary, Alberta, where a major sports and entertainment complex is proposed for an underdeveloped riverfront site that now includes auto dealerships and a bus station. Although a creosote plant there closed decades ago, creosote extends several meters below the surface across much of the proposed development area.

A recent environmental investigation required drilling sampling holes at multiple points across the property. Sonic technology and the rig’s maneuverability meant mission accomplished with practically perfect core samples.

Sonic drilling employs the use of high-frequency, resonant energy to advance a core barrel or casing into subsurface formations. During drilling, the resonant energy is transferred down the drill string to the bit face at various sonic frequencies. Simultaneously rotating the drill string evenly distributes the energy and impact at the bit face.

The resonant energy is generated inside the sonic head by four counter-rotating weights. A patented pneumatic isolation system prevents the resonant energy from transmitting to the drill rig and preferentially directs the energy down the drill string.

The driller controls the resonant energy generated by the sonic oscillator to match the formation being encountered to achieve maximum drilling productivity. When the resonant sonic energy coincides with the natural frequency of the drill string, resonance occurs.

This results in the maximum amount of energy being delivered to the face. At the same time, friction of the soil immediately adjacent to the entire drill string is substantially minimized, resulting in very fast penetration rates.

Sonic offers several distinct advantages over conventional technologies. Among them is the superior information provided by the continuous, relatively undisturbed core sample of unparalleled quality and accuracy through any type of soil — clay, till, loose or heaving sand, gravel, boulders or cobbles. When using the iso-flow groundwater profiling system, hydrogeological and geochemical data can be easily obtained.

Sonic drilling also reduces drill spoils and waste by up to 80 percent relative to conventional drilling methods. Unlike drilling with an auger, virtually no cleanup is necessary.

Superior well construction is another advantage. Sonic drilling causes minimal disturbance to the surrounding borehole wall, resulting in more efficient well development and performance. Then there’s the speed. Sonic drilling is up to two to three times faster than conventional overburden drilling methods.

Safety features of the LS250 MiniSonic rig include an interlocked rotation barrier, reduced noise levels, a dump mast and wiggle tail, and a rod presenter. The interlocked rotation barrier automatically slows head rotation when the barrier is open. The rig also provides lower noise levels when equipped with the Tier 4i engine package. 

The articulated mast and wiggle tail enable the mast to shift from left to right and front to back to position the mast precisely over the hole, eliminating time-consuming rig movements. The dump mast allows the crew to work from the ground, enhancing safety by avoiding stairs and safety rails often required when working from a platform.

The innovative rod presenter allows the rod and casing to be loaded horizontally, with an actuator that then presents the rod and casing vertically to the head. The head rotates 28 degrees to the side for sample extraction, while the head slide shift allows for unobstructed winch use down the hole.

The LS250 MiniSonic rig is capable of drilling to depths of up to 250 feet (78 meters) when used with a 4.75-inch (121 millimeter) casing. Its “big brother,” the LS 600 Sonic rig, can go even deeper — up to 600 feet (182 meters), as its name implies. The Boart Longyear lineup also includes high-quality sonic tooling, from bits and casing shoes to sonic rod, core barrel, casing and accessories.

As awareness of sonic drilling’s advantages continues to grow and as more and more geotechnical engineers specify sonic, the market will likely demand continued innovation and sonic drills capable of even deeper, larger-diameter samples. And Boart Longyear, already at the leading edge of sonic drilling, will continue to lead the way.

Waste rock dumps are often placed adjacent to mine pit areas, and as mining expands more room is needed for the waste rock. Certain physical and chemical characteristics of the waste rock dumps are often needed to better understand the geotechnical and geochemical behavior of the large dumps and to evaluate potential mineral value. Sonic drilling enables the collection of highly representative samples and excellent sample recovery. This method of drilling has been used for the re-exploration of dumps, tailings and heap leach pads.

Waste rock dumps consist of mainly unconsolidated material – and it’s often difficult to know how deep they are or what types of material they contain – which can lead to challenges in drilling. Sonic technology provides a solution by being able to produce 100 percent accurate in-situ core samples through varied ground conditions.

Boart Longyear Drilling Services took on the challenge of drilling core samples from the unconsolidated waste rock dump at Kennecott Utah Copper’s Bingham Canyon Mine. The intent of the drilling was to define the contents of the waste rock dump. The waste rock dump consisted of rock blast material ranging in size from 254 to 304.8 millimeters (10 to 12 in) in diameter and was made up mainly of porphyry deposits (granite-like rocks).

With a targeted depth of 213.36 meters (700 ft), the main goal was to provide a detailed continuous sample of the waste rock dump material and confirm bedrock depth. Boart Longyear also needed to install piezometers (water level monitors) and lysimeters (moisture content monitors). Geotechnical samples would also need to be taken every 6.096 meters (20 ft) to confirm stability and moisture content for the first 60.96 meters (200 ft).

Sonic drilling is the perfect method for drilling in unconsolidated material, such as the waste rock dump at the Bingham Canyon Mine, because of its sample recovery rate, straight cased borehole and the flexibility to offer geotechnical sampling via the split spoon sampler.

As drilling commenced, Boart Longyear took on the task one step at a time by tackling the depths in stages. For the first 106.68 meters (350 ft), they drilled a 228.6 millimeter (9 in) borehole while tripping the drill string every 6.096 meters (20 ft) to pull a split spoon geotechnical sample for the first 60.96 meters (200 ft).

For the second stage, the team drilled to 152.4 meters (500 ft) using a 203.2 millimeter (8 in) bit with casing. Moving deeper to 228.6 meters (750 ft), they used a 177.8-millimeter (7 in) bit with casing for the third stage. Surpassing their targeted drill depth of 213.36 meters (700 ft), the drillers still had not reached the bedrock formation.

Needing to find the true depth of the waste rock dump, Boart Longyear felt like the rig still had the capability and pullback to go deeper. Easing forward they drilled to 264.261 meters (867 ft) using a 152.4-millimeter (6 in) bit with casing. The last stage couldn’t be drilled with casing as they needed to move to a 101.6-millimeter (4 in) borehole. Leaving only the bit for the final push to 274.32 meters (900 ft) – and setting a new Boart Longyear record for sonic drilling – they reached a 28 percent greater depth than initially targeted.

It took 16 shifts of 12 hours (192 hours) to accomplish the new record depth for sonic drilling. Boart Longyear lost two of those shifts (24 hours) to rain. Another key accomplishment was the entire depth was reached through dry drilling and achieved 100 percent in-situ core samples at less than 1 percent hole deviation.