Ever wonder how K+S Potash Canada (KSPC) selects the best spots to mine potash? After all, the precious pink material is situated a mile beneath the Earth’s surface, and potash seams can vary in depth and quality or be located beneath geological features or underground conduits that pose hazards in solution mining.
Drilling for core samples is certainly part of the process. However, drilling is costly and provides limited information about the surrounding area, so KSPC uses 3D seismic exploration to “see’’ what lies below. 3D seismic exploration employs a series of controlled explosions to generate shockwaves that travel down into the Earth. The waves bounce off various types of rocks and return to the surface where data are recorded and later manipulated to produce images.
“We’re essentially painting a picture of what’s in the ground,’’ says Megan Frederick, Manager, Geology at KSPC.
Seismic crew laying equipment.
Frederick says her team sets out the explosive charges and surface receivers in a grid running east-west and north-south. This pattern allows the team to collect a 3D image showing the height, depth and width of rock formations. “Tighter grids produce more detailed images,” she says, adding that her team used a tight grid pattern comprised of 60 metres square boxes. “You’re better able to interpret the data when you have data points this close together,’’ she says, adding that specially trained technicians handle all the explosives work.
Frederick and her team mapped 65 sq. km of KSPC’s 100,000 acre lease during the first quarter of 2015. Together with the 98.4 sq. km mapped by Potash One, the previous owner, more than a third of the lease has been mapped using 3D seismic, which will be sufficient for 50+ years of mining.
While 3D seismic is effective and efficient, it can’t provide all information required to determine where future wellpads should be located.
“We’ve picked areas from the seismic where we’d like to drill,’’ says Frederick. “Once we have core samples, we’ll have a better understanding of the ore and its location. That’s why seismic is only half the story.’’
Frederick says the 3D seismic program was a “great success.’’ It met all objectives and came in ahead of time and under budget. “That’s always good from a project standpoint,’’ she said.
The KSPC Geology department leads the seismic project.
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