BABBITT- Surrounded by northern Minnesota forest, the drill rig at a site near here would be more at home in West Texas or another of the nation’s oil patches than in the North Country. But a potentially significant helium deposit prompted Pulsar Helium to bring the rig to the area.
It’s now operating off the Dunka River Rd. in hopes of better assessing the magnitude of the deposit of the inert gas detected there more than a decade ago. The gas has been in high demand in recent years for applications such as medical magnetic resonance imagery (MRI) and scientific nuclear magnetic resonance spectroscopy.
Exploratory boring
The appraisal well is being constructed for the American subsidiary of Vancouver, B.C.-based Pulsar Helium. The rig has an initial target depth of 2,250 ft. which may be extended to 2,500 ft if conditions are favorable. On paper, the rig is drilling an “exploratory boring,” which is how this hole in the ground is permitted.
“No one has done this before in Minnesota,” said Pulsar CEO Thomas Abraham-James during a tour of the rig site on Feb. 5. “There aren’t any regulations for drilling for helium. We are on new ground.”
Michael Sturdy, the General Manager of Operations for Pulsar explained that the Minnesota Dept. of Health issues the permits for exploratory borings. “As an exploratory boring,” Sturdy said, “the hole must be abandoned within ten years, including removing any casing installed and then sealing the hole with impervious grout to protect groundwater.”
Pulsar’s hole in the ground is not your usual exploratory boring for Minnesota. Here, such borings are usually drilled with a diamond drilling rig, which uses a small-diameter hollow coring tool encrusted with industrial diamond fragments to cut a solid rock core. Diamond drill rock cores are typically less than three inches in diameter, and usually smaller. These rigs operate in the Iron Range all the time, looking for iron, copper, and nickel mineralization.
Gassy holes
Why is Pulsar using an oil and gas rig to do its exploratory drilling? Because of the danger of high-pressure gas. Only an oil and gas rig has the equipment to handle high-pressure gas safely.
“When we discovered the helium,” said Pulsar’s Phil Larson, “gas coming out of the ground through the drill steel sounded like a jet engine.” At the time, Larson was working for Duluth Metals on a diamond drill rig, supervising the exploratory drilling for nickel-copper-platinum mineralization for which Duluth Complex rocks are known for.
The hole was the sixth in the exploration program for the mining firm back in 2011. Because there are small pockets of methane in some Duluth Complex rocks, every rig has a gas meter to detect combustible gas. The rig hit a high-pressure pocket, the gas alarm went off, and the crew vacated the rig for safety.
“Usually, the gas will vent within minutes to hours, and then the crew will go back to work,” Larson related. On this hole southeast of Babbitt, however, the gas was still flowing as extremely high velocity for over five days. Because the situation was novel for the area, no one had gas sampling equipment. Larson created his own using what he could find at Merhar’s Hardware in Ely.
Helium in the ground
“When the lab results for the gas came back, I saw that there was just two percent methane, which is below an explosive concentration. So, the crew went back to work and sealed the hole. It wasn’t until the next day that we really took a look at the rest of the results and it surprised us.”
Most of the gas was carbon dioxide, some nitrogen, and an astounding 10.5 percent helium.
“This is a unique occurrence for the Canadian Shield,” Larson remarked. There is no other helium occurrence like this within the core of the continent.
In the middle of every continental plate is a core of old rocks. For the North American continent, the core – or craton – is a mass of Precambrian rocks known to geologists as the Canadian “shield.” The Canadian Shield rocks are some of the oldest on the planet, one billion to almost 4 billion years old. Most of the shield’s rock is located in Canada, although northeastern Minnesota has the largest amount in the U.S.
The ancient rocks that Pulsar is exploring are around 1.1 billion years old, and that massive span of time is why the helium is there. The decay of natural radioisotopes that occur in all igneous rocks created the helium and it accumulated over this extremely long time period to create the high-pressure pockets that Pulsar is looking for.
Exploration
Pulsar’s exploratory boring is named Jetstream No. 1, in honor of the jet engine noise the Duluth Metals diamond drill hole made back in 2011. The appraisal hole is just 20 meters from that original Duluth Metals boring, which is now cemented to the surface. Pulsar has a good idea that gas is down there, having completed extensive geophysical surveys over the last year using gravity, magnetic and seismic tomography methods.
“The gas was discovered at 1,778 feet,” said Abraham-James. “We hope to intersect the original gas discovery, and then drill deeper to explore what we believe is down there based on our other results.” The firm did the other studies first since surface surveys are less expensive than mobilizing an oil and gas rig from its home base at Capstar Drilling in Wyoming.
The drilling started in January with a smaller rig, which set what is known as a conductor casing. This casing is to keep the wide top of the hole from collapsing, to remove unconsolidated material from the path of the big drill rig, and to protect the hole from groundwater, and to protect the local groundwater from the drilling operations.
The Capstar rig circulates drilling mud through the drill steel and back up the hole. The mud is a closed circuit between the rig and the borehole. This sort of drilling does not collect cores. The mud loggers, geologists who specialize in this sort of work, collect the rock fragments created by the drill bit which then flow upward in the mud. They categorize the fragments using microscopes and a portable x-ray fluorescence spectrometer, which at the drill site was the size of a coffee maker. The gas in the well is analyzed by the mud loggers with a portable mass spectrometer.
An integral part of the drill rig is the backflow preventer, which is huge piece of equipment designed to contain a sudden high-pressure flow of gas in the well. Only oil and gas rigs use these devices as standard equipment.
Once the drilling is completed and the casing in the exploratory boring is cemented into place, a “wireline” crew will come and log the hole using downhole geophysical instruments. If the helium find is viable, then Pulsar wants to build a production facility that will take up around an acre of grounds to pump and containerize the helium. The firm also plans to trap and sell the carbon dioxide from the discovery. Minnesota has a greater demand for industrial carbon dioxide than the current supply.
“Helium isn’t as big a production as mining,” Abraham-James said. “If we do build a helium plant here, we will create around 20 (direct) jobs.” Abraham-James did indicate that if Pulsar is successful, it will have a cascading economic effect as other firms looking for helium will want to do their own exploration in Minnesota.
Environmental
footprint
“We are really proud of our environmental footprint,” Larson said on the Feb. 5 site tour. The exploratory boring is on private land leased to Pulsar approximately 15 miles down Forest Service Rd. 112, along the southern border of Stony River Township.
“The land we’re on was logged and we only had to remove one tree,” Larson added. “We were able to use a pre-existing logging road and only had to remove eight trees to prepare it to bring in the rig … that’s a total of just nine trees.” Pulsar had to obtain a special use permit from the U.S. Forest Service to do the road work since the roads into the site are in the Superior National Forest.
The “drilling pad,” or area used up for drilling operations, is only 1.1 acres and was sited to use the area that was previously logged, so the impact on the surrounding forest was minimized. If the plant is built, it will be sited on top of the drill pad area.
“Our aim is to maximize our potential profit while minimizing our environmental impact,” Abraham-James said. “These are clean gasses coming out of the ground and we want to keep this a clean operation.”