GRAND FORKS, N.D. (AP) — A few hours’ drive from the Bakken oil fields lies a treasure trove for geologists: rock from nearly every oil well ever drilled in North Dakota, under one roof.
The rock is tucked neatly into cardboard boxes stacked on numerous warehouse storage shelves in the Wilson M. Laird Core and Sample Library on the University of North Dakota campus in Grand Forks.
“We’ve got about enough core to lay out from here to Fargo, 85 miles or so,” director Jeff Bader said.
The library is part of the North Dakota Geological Survey and houses two forms of rock: core and drill cuttings. Core refers to cylinders of rock that oil companies pull out of the ground by attaching special bits to the end of their drills that make clean cuts as they preserve large chunks. Coring often is done when companies explore new places to establish wells.
Cuttings are smaller pieces of rock chopped up by a different type of bit. They are brought to the earth’s surface in a muddy mixture, then washed off and analyzed to determine which rock formations the company is drilling through. That ensures an oil well is placed exactly where it’s intended to go.
By state law, oil companies typically have six months to keep their core and cutting samples before they must send them to the library, The Bismarck Tribune reported.
The library has grown with the state’s petroleum industry, giving decades of geologists the opportunity to use its rocks to pinpoint where their companies should drill next. That work isn’t likely to stop anytime soon, and lately the library has found additional purpose as the energy industry eyes new ways to make use of rock buried thousands of feet below the North Dakota prairie.
The library spans 52,000 square feet and includes three labs with lengthy tables where geologists can lay out numerous boxes for their research.
“It was crazy busy when the Bakken boomed,” Bader said.
The facility grew cramped after shale fracking took off more than a decade ago. Oil companies began using horizontal drilling and hydraulic fracturing to access new layers of rock in the western North Dakota oil fields, and they shipped enormous amounts of that rock back to Grand Forks for storage. Company geologists visited the library often and still do, using the rocks already there to figure out the next big play.
The state in 2016 spent $13.6 million to expand the facility. Bader estimates it won’t run out of room again for another 65 years.
The earliest cuttings on its shelves stem from the work of Des Lacs Western Oil. The Minot-based company drilled for oil a century ago but came up dry.
Wilson Laird, who became state geologist in 1941, championed a host of laws and rules anticipating someone would strike oil one day. Among them was a requirement that companies preserve their drill cuttings and make them available to the Geological Survey. The rules have evolved over time and now require the rock to be sent to the core library.
The lucky break came in 1951 for Amerada Petroleum Corp., which struck oil near Tioga. The company’s discovery launched North Dakota’s first oil boom.
Rock from that well is packed into cardboard boxes just like all the other samples, and it’s something of a mecca for oil enthusiasts who visit the library and make it a point to stop by its shelf.
On a recent tour of the library, Bader and subsurface geologist Timothy Nesheim pulled down one of the boxes from that well. It contains rock from a depth of over 11,000 feet.
The rock is a light gray color but every so often shows a bit of brown, which Nesheim said is an oil stain.
Even he still gets excited by that rock, and he’s worked with the Geological Survey for years.
“Oh man,” he exclaimed as he looked at it earlier this spring. “You can actually see some of the pore space. You can actually see openings in the rock. You can’t always see that.”
Before the library was established in 1980, the Geological Survey kept its cores and samples in a Quonset hut behind the UND football field. Longtime State Geologist Ed Murphy recalled that it lacked heating, an inconvenience for geologists from Houston who would sometimes visit the chilly facility in winter and attempt to wet the rock to see it better.
“They were always complaining that it would freeze up on them,” he said.
Today’s geologists can run a number of tests on rocks from the library. One room is equipped with black lights to detect oil fluorescence, a yellowish glow that indicates the presence of oil within a rock.
Nesheim and Bader like to tell the story of how, in the days before the black light lab, Whiting Petroleum packed a number of geologists into one of the library’s windowless bathrooms. They closed the door for complete darkness before shining a black light on some core.
Their work paid off, as it led the company to discover the potential for oil development in the Pronghorn formation near Dickinson.
Activity at the library has slowed over the past year amid the coronavirus pandemic, which halted travel, causing demand for oil to plummet and sending prices crashing.
The downturn gave library staff time to catch up photographing all the rock that overwhelmed the facility during the boom days of the Bakken rush. They took 30,000 photos last year to upload online, accessible to other geologists via a subscription service.
“If somebody is in Texas or Denver, they can look at that core before they come up here and have an idea” of which boxes to pull from the shelves, Bader said. “Their time is valuable.”
Lately North Dakota’s other major fossil fuel industry -- coal -- is taking notice of the rocks at the library. So too is the state’s ethanol industry as both develop projects to capture their plants’ carbon emissions and store them in rock layers underground.
Carbon capture technology is in its infancy, and federal tax credits are helping fuel the projects. Supporters of the technology view it as a way to meet the public’s growing demand to address climate change.
Research into the subject has grown over the past two decades, and three operators of coal and ethanol plants in North Dakota have projects underway to see if they can make the technology work.
“Certainly there’s been an increase in interest in the last five years,” Murphy said.
Minnkota Power Cooperative is gearing up to apply for state permits to build and operate an injection site next to the Milton R. Young Station, a coal-fired power plant near Center northwest of Bismarck.
The effort, known as Project Tundra, has been in the works for several years. Minnkota has relied on research from the Energy & Environmental Research Center a few blocks away from the core library to test whether its plans are feasible.
“When we started the project, we needed to have some scope and sense of what the potential was,” said Shannon Mikula, special projects counsel and geologic storage lead for Minnkota, which serves eastern North Dakota and northwestern Minnesota. “The core library really was instrumental in helping us establish a target.”
Researchers examined rock already at the library from the Broom Creek formation to see if it had the right characteristics for carbon storage. Broom Creek is one of the layers of rock about 4,900 feet deep where Minnkota is looking to store carbon dioxide once it’s separated from the rest of the exhaust gas at the power plant.
“Over the years, the oil industry has flown over that formation because it’s not oil-bearing, but it’s got really good sand properties for CO2 storage,” Mikula said. “That core helped us identify that valuable formation.”
Minnkota has drilled two test wells, pulling out 3,000 feet of core from the Broom Creek and other formations for analysis. That rock is now housed in the core library.
Carbon storage projects in North Dakota also are focusing on the Inyan Kara formation. Some of that rock is out on display in one of the library’s labs. Bader has done extensive research on it for another purpose: to identify where the oil industry ought to inject saltwater, a byproduct of oil drilling.
His research also has pieced together its geologic history, showing how the formation was deposited when a massive inland sea once covered parts of North America over 100 million years ago.
“This is going to be your best for CO2 because it’s coarser,” he said, picking up a piece that feels like sandpaper to the touch. “When they decide to put their well in and their CO2 is going to be injected, they want to end up here.”
Carbon storage also requires significant impermeable rock that seals in carbon dioxide so the plume doesn’t migrate back up to the earth’s surface and enter the atmosphere. That too is something researchers examine closely as they develop carbon storage projects.
The library houses rock from other industries as well, some of which have been more successful than others over the years. Murphy described it as a “hodgepodge” of industries -- everything from uranium exploration in the 1970s during the nuclear power boom to a more recent search for diamonds in the northeastern part of the state.
“We’re all about preserving that core,” Murphy said. “Who knows why 50 years from now they’ll want to be looking at those rocks.”