LSU Civil, Environmental Engineering Professor Assesses Impact of Sulphur Mines Salt Dome Cavern Collapse on Well Water
November 18, 2024
BATON ROUGE, LA – The Gulf Coast is home to more than 500 salt domes, and at least 200 of those are located in Louisiana. While salt domes and their caverns can be beneficial, such as being used to hold petroleum reserves, they can also be a possible hazard should the caverns collapse. The Louisiana Department of Energy and Natural Resources (LDENR) currently has its eye on two caverns in Sulphur, La., and have awarded a $156,602 grant to LSU Civil and Environmental Engineering Professor Frank Tsai to assess the impact a collapse would have on well water in the area.
Tsai, who is also the director of LSU’s Louisiana Water Resources Research Institute (LWRRI), was asked to design a groundwater model for the LDENR Office of Conservation that shows how long it would take brine and sulfide from a collapsed Sulphur Mines Salt Dome cavern to reach public supply wells, tapping into the Chicot Aquifer.
“In Sulphur and Lake Charles, there are two major aquifers for drinking water and industry,” Tsai said. “One is 500 feet below the surface, and the other is 700 feet below the surface. I’m working on predicting how long it will take brine and sulfide to travel to the water supply wells.”
The two aquifers Tsai is referring to are within the Chicot Aquifer. According to LWRRI, the Chicot Aquifer is one of the most important aquifers in Louisiana and a major water resource in the southwest part of the state that supplies water for agriculture, aquaculture, industry, and public section. It provides approximately 660 million gallons per day that is mostly used for irrigating rice and soybean fields, as well as raising crawfish. Brine or hydrogen sulfide from a collapsed salt dome cavern could be catastrophic to this water supply.
Concern of the leak into the Chicot Aquifer was so great that, in 2023, former Louisiana Governor John Bel Edwards issued an emergency regarding the situation.
The two caverns in the Sulphur Mines Salt Dome that are being carefully observed by the LDENR Office of Conservation due to their structural and mechanical integrity are Caverns 6 and 7. Combined, they can both hold nearly 20 million barrels of oil. Should one collapse, it could leak a substantial amount of brine and sulfide into the Chicot Aquifer, as well as create a giant sinkhole similar to the one in Bayou Corn in 2013.
“The cavern will leak once it starts to lose pressure, and once it collapses, it will likely create a sinkhole in the land surface,” Tsai said.
Caverns 6 and 7 were originally drilled as brine mining wells to supply salt water for petrochemical processes in the mid-1950s until the U.S. Department of Energy took them to use as a petroleum reserve until the mid-1990s, when they were transferred back to a private company, PPG Industries, now known as Westlake Chemical. Both caverns have remained inactive since 2014 and have been monitored since. In 2021, it was discovered that both caverns, particularly Cavern 7, had pressure issues that led to oil seepage around the dome along with seismic activity. To prevent collapse, Westlake Chemical has been pumping saltwater into Cavern 7 to prevent a rapid decline in pressure.
Though the clock is ticking, Tsai hopes that his research will help Calcasieu Parish prepare for what’s to come.
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