A global and dedicated engineering department works tirelessly to improve safety, increase productivity, and solve drilling challenges in collaboration with drillers and operations. Both Boart Longyear™ Drilling Services and Boart Longyear Products divisions benefit from the opportunity to collaborate on equipment design and prototype development with a global team of engineers.

For the Large Rotary Drilling Services division, the engineering team makes incredibly powerful and advanced rigs like the LR™500 possible. Recognizing Boart Longyear’s LR™300 had depth and pullback limitations, the engineering team built the significant and incredibly powerful LR500. Completely designed and developed internally, the LR500 was built specifically to meet the increasing needs for deeper dewatering wells for Nevada mining.

While there are deep hole drill rigs in the market, not all can achieve a 60 inch (152 centimeter) diameter hole for dewatering wells for mines. The LR500 can drill hole sizes large enough to accommodate 20 inch (50 centimeter) casing down to 5,000 feet (1,524 meters). While there are rigs in the oil and gas market that are capable of more pullback, these slim hole rigs are not capable of drilling the diameters achievable by the LR500 while also being able to install the casing.

The size and weight of the casing is what sets the LR500 apart from other large rotary drill rigs in the industry. The LR500 can drill deeper with 500,000 lbs (35714 stones) of pull-back. This capability allows the rig to set the casing without having to move the rig off the hole and use a crane to set the casing. This is an all-around savings in time, labor, and equipment mobilization and demobilization costs.

Another significant benefit of the LR500 is that it is electrically powered. It seamlessly connects into the power grid source. This technology provides a considerable benefit for emissions reduction and fuel savings. Decreasing emissions was extremely important to the Nevada mining client that commissioned the LR500.

The LR500 is equipped with sensors and provides the driller with constant real-time feedback about ground conditions being encountered down the hole. The driller sets up drilling parameters and the rig will set off alarms or shut down depending on those set parameters. When drilling conditions change as the hole progresses, for example, if the tri-cone drill bit hits a void, the rig will throw an alarm or shut down and allow the driller to make the proper adjustments.

In addition to the automated drilling features, the LR500 is equipped with a fully hands-free rod handler. A mechanical rod arm picks up a rod from the rod rack and feeds it into the mast, allowing the head to begin threading the rod. This hands-free technology allows making or breaking rods when tripping in or out. This is a substantial safety feature that removes drillers and driller assistants away from the hazards of rod handling, making and breaking rods, and being under a suspended load of a rod.

Drillers are in a climate controlled cab, protected from the elements. Several screens and a camera system allow the driller to monitor important areas of the rig from the cab – like the draw works, the head, rod handling, work deck, mud tank system, etc. The cab is also equipped with an intercom which allows the driller to communicate with the crew deck.

This unique drilling process uses dual wall drill pipe and drilling fluid along with the injection of air in order to drill large diameter holes. In the drill string, perforations allow the air to return up the center, following the path of least resistance. The air traveling back up the inner tube evacuates the fluid inside the drill pipe, which in turn allows the mud fluid on the backside of the drill rod to move down the hole, across the bit face and back up the center to surface bringing the cuttings with it. Using Dual Tube Flooded Reverse (DTFR), fluid returns inside the dual tube pipe and cannot escape into the formation. Instead of maintaining fluids at the surface and circulating throughout the wellbore, DTFR allows drilling to take place with the borehole fluids at their naturally occurring level.

Most other contractors drill a pilot hole at a smaller diameter and then go back in and ream the hole again in the larger diameter. Sometimes this can take several passes. The beauty of DTFR is the capability to drill to the large diameter and depths with a single pass. This shortens the total time the hole is open and decreases risks of collapse and flooding the formation. Not only is DTFR more efficient, but it minimizes development time and maximizes well efficiency.

Boart Longyear uses a self-contained drilling fluids system where, as the drilling fluids return to the surface, they are collected in a tank where the cuttings are stripped from the fluid through shale shaker screens and de-sanding units and the drilling fluid is then reused in the drilling process. Self-contained drilling fluids tanks ensure proper mixture and maintenance of drilling fluids and save money by eliminating the need for a pit. Eliminating a pit for drilling fluids reduces the drill pad size, may require fewer disturbance permits, and eliminates the need to backfill a pit.

The LR500 has outperformed the expectations of the drillers and the engineers. The first hole drilled was a true straight hole and was accomplished in a single pass. It was critical that the first hole the LR500 drilled be exceptionally straight because it was drilling in extremely close proximity to an underground stope. There was a real possibility of intersecting and flooding that stope. But the results from the LR500 impressed both the client and the drillers. The ability to accomplish such straight holes is attributed three major features: the automated drilling features, an electric hoist, and the larger tooling.

The constant real-time feedback during drilling allows the driller to make adjustments while drilling to accommodate changing conditions as they happen down the hole. The electric hoist allows very finite control for immediate adjustments in weight and rotation tuning. The larger the tooling the more rigid it is, so it offers a straighter hole. The stout tooling and bottom hole assembly maximizes potential for plumbness and alignment.

After completion of the first hole, the LR500 was moved infield with the mast and base assembled. This is a time-saver because once you’re onsite, there’s a lot less disassembly of the rig to move hole to hole. The LR500 was moved 1.5 miles in about 3 hours. The rig sits on a modified track hoe and was designed with the support equipment needed for the move.

On the first well, traditional gravel was used. On the second well, the client ordered glass SiLibeads® to set the screen casing, another unique component of the project. The filter pack glass beads were substituted for gravel to minimize biological build-up, maximize well capacity, and conserve energy and backwash water.

Whether you need a mineral exploration drilling contractor, water services, or production drilling, you need a contractor with a rock-solid reputation and a track record for safety and innovative solutions. Boart Longyear operates safely with integrity and drills for results, consistently delivering innovative solutions to the most technical drilling challenges, in some of the most complex operating environments around the world. The LR500 is just another example of how we accomplish it all through our investment in safety, our people, and equipment.