The Louisiana Office of Conservation on Monday ordered Texas Brine Co. LLC to employ an imaging technique to assess sediments under an 8.5-acre sinkhole in northern Assumption Parish that does not require drilling two 6,000-foot-deep wells.
Issued late Monday afternoon, the new order from Louisiana Conservation Commissioner James Welsh prompted an early end to a Texas Brine lawsuit in the 19th Judicial District Court seeking to block the Dec. 7 order calling for the wells.
The wells, which the company opposed as too slow and risky, would have been used to try a different kind of seismic imaging technique.
The state agency and the Houston company were set for a hearing at 9 a.m. Tuesday before state District Judge Wilson Fields in Baton Rouge.
“It has been withdrawn,” Sonny Cranch, Texas Brine spokesman, said of the company’s Dec. 28 lawsuit against the state Office of Conservation, Welsh and the state Department of Natural Resources.
Welsh ordered that Texas Brine can use 3-D seismic imaging instead. The method employs sound waves projected from the surface and bounced off underlying layers to create a detailed, three-dimensional picture of the subsurface.
Texas Brine officials and Welsh said in statements Monday that the shift in techniques could lead to learning what is happening under the sinkhole months sooner than the method using the two wells.
“We look forward to working closely with DNR’s personnel and contractors, together with Assumption Parish officials, as we design and execute these imaging efforts,” Bruce Martin, Texas Brine vice president for operations, said in the company statement.
The new order also requires Texas Brine to drill a new 1,000-foot well west of the sinkhole for seismic monitoring and assessment and to build a permanent seismic array in a separate company salt cavern well to watch for tremors and do stability monitoring, Office of Conservation officials said.
About 150 households in Bayou Corne and Grand Bayou have been evacuated since Aug. 3, the same day the sinkhole was discovered in swampland south of La. 70 South in northern Assumption Parish.
A Texas Brine salt cavern in the Napoleonville Dome has been the suspected cause of the sinkhole and the source of subterranean oil and gas releases in the area, scientists have said.
But the Office of Conservation and its scientists want a seismic picture of the subsurface to better understand what is happening there.
Scientists have said they think a sidewall in the underground cavern, which is near the western edge of the salt dome, caved in thousands of feet underground.
Scientists have said they are trying to determine the stability of the sediments believed to have been shaken up after the failed cavern wall allowed 3.3 million of cubic yards of sediment from outside the salt dome to flow inside the cavern.
More material has continued to gradually fill the remaining cavern space since the initial wall collapse, Texas Brine has reported.
Scientists are looking for voids in the shaken subsurface that not only could present a stability risk but also act as reservoirs for escaping methane believed to be an explosion concern for residences at the surface.
The work is also aimed at determining the source of crude oil and methane that scientists have said they think the failed cavern released from natural rock formations thousands of feet down along the outer face of the salt dome.
In its lawsuit, Texas Brine had argued that the two deep wells would take too long and pose a risk to the community when quicker, safer methods were available.
In a visit to the company’s site Monday in Grand Bayou — before the Office of Conservation announced the revised order — Cranch said the company was preparing to do the 3-D seismic work on its own.
Company contractors had also finished the first part of another kind of seismic testing called a vertical seismic profile and were preparing for the next step.
In the news release Monday, Office of Conservation officials said they originally wanted Texas Brine to do the 3-D work, but the company estimated results would take two years and added it was concerned about land access.
The 3-D technique requires a land-intensive, tightly focused grid laid out across the surface in which sound waves are created and then collected.
Welsh ordered Texas Brine on Dec. 7 to drill the two deep wells so the wells could start gathering seismic data with them by August.
Conservation officials said that since then, Texas Brine has changed its time estimate to do the 3-D seismic survey, saying it could be finished by April.
In Monday’s order, Texas Brine has been given until April 21 to complete the 3-D seismic survey and turn over the data to the Office of Conservation.
Welsh said his office is working to ensure public safety and get residents’ lives back to normal.
“Texas Brine has indicated it can meet this shorter timeline by using 3-D seismic imaging,” Welsh said in the statement, “and we hope this is a sign that the company is finally beginning to respond with the sense of urgency required in responding to this ongoing situation.”
Welsh said Texas Brine will continue to be held accountable for the other directives contained in his Dec. 7 order and further orders may be issued if the 3-D seismic imaging does not provide data in a timely manner.
Interim DNR Secretary Stephen Chustz added in the statement that he is hopeful but also offered a caveat.
“If Texas Brine continues to drag its feet, we continue to suggest that they consider buying out the people who want to leave,” he said.