3D study points to stability of salt dome in Bayou Corne
Bayou Corne, La — Preliminary imaging results from the recently completed 3D survey of a 2.28 square mile area, stretching from the Texas Brine site to beyond the Bayou Corne community, indicate that the western edge of the Napoleonville Dome has remained stable.
The imaging was done after the formation of a sinkhole just west of Brine Cavern 3 on August 3, 2012 and is in the same location as it was prior to the sinkhole. Imagery also indicates that there are no subterranean voids or evidence of additional hydrocarbon pockets that could pose future problems in the area.
The 3D study produced high-resolution images, compiled using data recorded from over 2,500 energy source points, painting a picture of the geology from the surface to a depth of 7,000 feet.
“We now have a clearer understanding of what occurred and how the sinkhole formation and western face of the Napoleonville salt dome beneath the sinkhole are related,” said Bruce Martin, Texas Brine’s vice president for operations. “This information provides a valuable analytical tool for the Blue Ribbon Panel, formed at the direction of Governor Jindal and tasked to define a path forward based on facts in the interest of public safety.”
The imaging indicates that –
• There are no subterranean void spaces that could lead to the development of another sinkhole.
• There are no natural gas pockets that could continue to feed the gas that is now being vented and flared from the shallow aquifer.
• There is no evidence of multiple hydrocarbon zones to supply the sinkhole or MRAA.
• Other than the collapse zone immediately surrounding the sinkhole, the western flank of the dome is a stable formation.
• The collapse zone around Brine Cavern 3 is limited to a very localized area at a depth of approximately 800 feet and includes a small vertical riser along the outside of the salt face.
• The area of the subsurface, which was disturbed by the sinkhole, is contained within the berm, and remains far south of Highway 70.
• Hydrocarbons remaining in a portion of the “Big Hum” appear to have been liberated and have dissipated through the surrounding sediment.
“We have achieved initial containment of the sinkhole with the construction of the berm,” Martin said. “This 3D data tells us that there are no natural gas pockets that could continue to feed what is currently being vented and flared, and that the western flank of the dome appears be stable.”
Additional data processing is underway to better determine the location of any remaining gas in the aquifer. Experts are working to integrate existing engineering, geologic and recent seismic data to determine how to best mitigate any remaining shallow gas.