Well to be drilled to study sinkhole
Crews finished driving metal casing into the ground Sunday near a salt cavern in Assumption Parish and plan to begin drilling an observational well into the cavern to see if it caused the large sinkhole near Bayou Corne, a spokesman for the company that owns the cavern said.
Sonny Cranch, a spokesman for Texas Brine Co. LLC of Houston, said workers with Riceland Drilling Co. of Lafayette began installing the 20-inch casing on Friday and finished sometime midday Sunday.
Cranch said crews drove about 400 feet of the casing until it hit the 300-foot-thick caprock overlying the Napoleonville Salt Dome, a 1-by-3-mile solid salt deposit used for brine production and hydrocarbon storage.
“They’re now doing all the prep work to start drilling within that 20-inch diameter casing,” Cranch said.
That prep work includes installing safety equipment for the next phase of drilling, Cranch said.
From here, crews must drill through the caprock, Cranch said. Once the rock has been penetrated, crews will begin directional drilling toward the cavern.
Texas Brine still estimates the process will take about 40 days, Cranch said.
“So far, we’re on schedule,” Cranch said Sunday. “But again, you never can tell.”
The sinkhole emerged Aug. 3 south of La. 70 South in northern Assumption Parish, swallowing up earth and trees and leaving behind a slurry area about 200 feet from an abandoned salt cavern operated by Texas Brine.
Department of Natural Resources scientists believe the cavern may have failed and caused the sinkhole and natural gas bubbles in nearby bayous.
Louisiana Office of Conservation Commissioner Jim Welsh ordered Texas Brine on Aug. 9 to begin drilling a relief well to determine the integrity of the cavern.
The drilling rig was fully assembled Friday after it was moved part by part to the observational well location, about 1,000 feet southwest of the sinkhole, Cranch said.
Crews continue to work on the observational well 24 hours a day, Cranch said.
Cranch said Sunday that sinkhole conditions had remained virtually unchanged since Friday.
However, authorities were unable to fly over the slurry area Sunday because of heavy rain, said John Boudreaux, director of the Assumption Parish Office of Homeland Security and Emergency Preparedness.
Gov. Bobby Jindal ordered evacuations of about 150 residences in the Bayou Corne community shortly after the sinkhole was discovered.
Texas Brine has established a fund to assist people who have evacuated as part of an agreement in the company’s original permit for the cavern, the Governor’s Office of Homeland Security and Emergency Preparedness has said.
Crosstex has said it will begin Tuesday shifting liquid butane from one underground storage cavern to another in the Napoleonville Salt Dome about 1,000 feet farther away from the sinkhole.
Crosstex spokeswoman Jill McMillan has said the company is moving the butane to alleviate community concerns despite the company’s belief that the butane poses no public threat.
The Crosstex, Texas Brine and other caverns have been carved out of the Napoleonville Dome.
The large underground salt formation was pushed up vertically from ancient seabeds and, for decades, industry has used the dome for brine production. The perimeter has also been the focus of intensive oil and gas exploration.
Hollowed from the solid salt formation, caverns left by brine production are often used later for storage of natural gas, butane and other hydrocarbons. Brine is used for several industrial processes.