Louisiana sinkhole – Crude oil in cavern and sinkhole being removed, evacuation order remains

Texas Brine Co. of Houston began removing crude oil trapped in a failed company salt cavern inside the Napoleonville Dome in northern Assumption Parish, company and government officials said on Wednesday, October 17, 2012. The state Office of Conservation approved the removal plan on Tuesday. The plan to remove crude oil from the cavern follows the Louisiana Office of Conservation Commissioner Jim Welsh’s order last week saying that the cavern caused the sinkhole.

The sinkhole is located between Bayou Corne and Grand Bayou and was found on the morning of August 3, 2012 leading to a mandatory evacuation of 150 homes. The evacuation order remains in place.

Texas Brine workers began pumping brine through an observational well that had been drilled recently to find the cause of a 4.2-acre sinkhole nearby. The observational well provides access to the salt cavern the company had been using.

“Every barrel (of crude) taken out is a barrel (of brine) going in,” said John Boudreaux, director of the Assumption Parish Office of Homeland Security and Emergency Preparedness.

Patrick Courreges, Louisiana Department of Natural Resources spokesman, said the replacement brine will be used to maintain stable pressure in the cavern.

State, parish and company officials said no solid estimates are available on how much oil is in the cavern.

Salt dome vent well and sinkhole profile map

Assumption Parish - Operational situation summary

(as of October 15, 2012 – full report here)

Emergency management:

– Parish Emergency Declared – 19 June 2012
• Extended 30 days on 19 July 2012
• Extended 30 days on 17 August 2012
• Extended 30 days on 14 September 2012
• Extended 30 days on 12 October 2012
– State Emergency Declared – 3 August 2012
– LA Hwy 70 Open for traffic
– Mandatory Evacuation still in effect
– Security plans in place to secure slurry area
– Parish continues blog to inform residents
– Texas Brine issuingg financial assistance for residents – St. Joseph the Worker Church Hall in Pierre Part – HOTLINE 1-877-281-7311
– Facilitating the [email protected] for questions
– Public Briefing to be discussed and scheduled
– Isaac Isaac Recovery in progress Recovery in progress

Assumption Parish - Scientific situation summary

(as of October 15, 2012 – full report here)

   USGS:

– Source of seismic activity estimated between 200 and 600 meters deep
– Continuing to monitor seismic activity at the six seismograph locations
– USGS reported limited seismic activity—average of one tremor a day—direction NW of sinkhole and other side of the pipeline right-of-way—Dr. Horton stated the science behind the recent events does not suggest a heightened level of risk at this time.
– USGS confirms no seismic activity in the area of the butane caverns
– Representative of the science group discussed dome mechanics and surveys for investigatory well with representative of USGS and Sandia National Lab
– In response to Texas Brine’s assertion that region seismic activity caused their cavern cavern to be compromised USGS stated (on 25 Sept. 2012) that it is their belief to be compromised, USGS stated (on 25 Sept. 2012) that it is their belief that the seismicity is a consequence of the collapse of the cavern, and not the cause of the collapse of the cavern and the formation of the sinkhole

  Scientific Workgroup theories of cause:

• Salt Dome moving – natural migration of gas
• Failed cement casing in OXY #3 well
• Cavity Cavity Failure Failure
• Salt / Caprock falling from top of the cavern
– Natural
– Man-made made (including penetration into sediments by cavern) (including penetration into sediments by cavern)
• Gas storage cavern connections, communications by fractures
• Low permeability seepage of gas into OXY #3 (source unknown)
• Regional Regional Tectonic activity (movement on growth faults) Tectonic activity (movement on growth faults)
• A combination of above events

Sources: theadvocate.com, edsuite.com

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Louisiana sinkhole – Crude oil in cavern and sinkhole being removed, evacuation order remains