The project was delayed by COVID-19 but work to plug out-of-service brine wells in Gratiot, Isabella, and Midland counties got started this summer in a collaboration between Dow Chemical Company and the Michigan Department of Environment, Great Lakes, and Energy (EGLE). Brine is a naturally occurring liquid that contains high concentrations of mixed chlorides and other salts.
EGLE approached Dow in January 2018 about plugging the wells using today's specifications, said Jim Armbruster, of EGLE's Oil, Gas, and Minerals division.
Located mainly on private property, the wells are some of the first-ever drilled by Dow, having used common practices at the time. The oldest brine wells there were drilled in 1892.
The abundance of brine in the Midland area was the basis for the founding of The Dow Chemical Company. Natural brines were extracted from wells installed in deep bedrock formations, in this case the Marshall Formation.
To locate the wells, Dow used historical records and aerial photography. Participation by property owners is voluntary.
"EGLE oversees all aspects of the plugging program, including interacting with the affected property owners and ensuring the well areas are scanned for residual naturally occurring radioactive materials," said Armbruster. "EGLE staff review and approve the plugging plans, site preparation activities, and site restoration following remedial plugging operations."
Plugging the wells involves removing previous plugging material and debris and filling the well with cement. After the cement sets up after several hours, the surface casing is cut at a minimum of 4 feet below surface grade and a steel plate is welded onto the casing with the permit number permanently affixed to the plate, noted Armbruster.
The project — consisting of approximately 150 wells — is expected to take several years to complete. It is the second largest project of its kind in Michigan. Chevron has a larger, on-going similar project.