Seismic testing underway for carbon dioxide sequestration project

Seismic testing is underway at the site of the proposed carbon capture and storage project in development at the Great Plains Synfuels Plant. The testing is part of the ongoing baseline monitoring operations for a project that will permanently store carbon dioxide from the plant underground. 

Seismic surveys are a tool geologists and geophysicists use to understand subsurface geology by looking at rock layers miles under the ground.

During the testing of the area, 11 pounds of dynamite will be placed in 120-foot-deep holes every 100 feet. According to Brad MacKinnon, project manager of Echo Seismic, the company conducting the seismic testing at Dakota Gas, both dynamite and vibroseis (which vibrates the ground at high frequency) will be used in the testing. “While dynamite typically has more accurate data, it does come with a higher cost and longer preparation time, so both methods will be used for a direct comparison of the same location. This will help with future monitoring of the injection well,” MacKinnon said.

After the dynamite is placed in the holes, it is detonated one at a time and nearly 500 geophones attached to a computer record the energy that comes back after the blasts. “The energy from the blast goes down into the ground and we record the amount of energy and the time it takes for it to come back,” MacKinnon said. “That tells us the density of what is down there.”

The data from the testing will give a baseline reading of the geology and formations of the area where carbon dioxide (CO2) from the plant will be injected. Once the CO2 is injected, upcoming seismic surveys will track its movement.

“The CO2 will be injected in the Broom Creek (rock) Formation 6,000 feet underground,” said Kevin Solie, Basin Electric senior environmental compliance administrator. “Directly above and below the injection site are nearly impervious 130-foot-thick sealing rocks that will keep the CO2 in place. And above that, there is nearly a mile of rock between injection zone and the nearest fresh water zone, so once the CO2 is in the ground, we believe it’s there to stay.”

Basin Electric, Dakota Gas, the Energy and Environmental Research Center, and Carbon Vault (the company that will construct and operate the injection wells) are currently in the process of preparing a permit application to the North Dakota Industrial Commission, the agency that regulates the underground storage of CO2. The seismic testing is part of that permitting process.


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