By David J. Mitchell
River Parishes bureau
September 24, 2012
A mechanical breakdown halted the final push Friday to finish a well that will be used to peer into an abandoned salt cavern suspected as the cause of a sinkhole in Assumption Parish, but drillers were poised to resume their drive Saturday morning to discover what the mysterious cavern might reveal.
Parish officials had said they hoped drillers would be able to break through the top of Texas Brine Co.’s salt cavern by Friday afternoon, a step that would clear the way for a variety of high-tech tests on the cavern’s condition.
Drilling has been under way for more than a month, despite delays from Hurricane Isaac and drilling equipment replacement for the final push down.
“The resumption of drilling is not expected to occur until early Saturday morning,” Texas Brine officials said in a statement Friday.
The mechanical failure was reported about 9:45 a.m. Friday by parish officials in a blog post.
The sinkhole was found Aug. 3 in Texas Brine swampland property between the Bayou Corne and Grand Bayou communities south of La. 70 South, prompting the evacuation of residents from about 150 homes in the vicinity. The sinkhole appeared after two months of natural gas releases in area waterways and earth tremors, both of which have continued.
The sinkhole, which has grown larger as dirt and trees on its rim have sloughed off and fallen into the water since it emerged, including this week, is now about 475 feet across and an estimated 4 acres in size, according to new parish dimensions.
The Louisiana Department of Natural Resources ordered the well be drilled after scientists suspected a nearby company salt cavern in the Napoleonville Dome failed, released its brine contents and caused the sinkhole.
John Boudreaux, director of the parish Office of Homeland Security and Emergency Preparedness, said Friday’s mechanical failure involved a mud pump near the bit at the tip of the drill pipe.
He said the failure forced the entire drill pipe to be removed Friday so the bit and pump could be replaced and reinserted in the drill hole, which has reached 3,180 feet in depth. The bit had reached a point about 300 feet above the cavern roof, Texas Brine officials said.
Boudreaux said the mud pump is used to circulate drilling mud, which is used to lubricate the drilling process and bring excavated material to the surface.
Barring other delays, Texas Brine spokesman Sonny Cranch said, drillers, once work begins Saturday, might be able to reach the cavern roof in about 10 to 12 hours.
Boudreaux said that once the drillers break through the cavern roof, they will have to take time to clean out the well bore before they start putting scientific probes into the cavern.
He said the first planned operation will be a seismic test on the cavern. But he also said entry into the cavern itself could provide early indications about cavern conditions.
For instance, if the drilling mud stops returning the surface and falls downward in the cavern, this could indicate the salt cavern has lost its brine, Boudreaux said.
The abandoned cavern had been filled with brine and diesel by operators. Similar materials have been found inside the sinkhole.
Should a gas pocket be hit, Boudreaux said, drilling mud might not fall away, but natural gas could spurt up the well bore and have be vented off before any tests could be done.
During the weeks-long drilling process, other developments have emerged, state and parish officials said:
- DNR officials said Friday that data from natural gas sampling in Bayou Corne have been posted on the agency’s website at http://dnr.louisiana.gov/index.cfm?md=pagebuilder&tmp=home&pid=961. However, the chemical simplicity of natural gas compounds requires greater expertise and time than the analysis of other, more complex hydrocarbons.
- More of the sinkhole’s bank caved in for a second time in three days Thursday morning as a 25-foot-long section fell into the water after 200-foot-long section had sloughed off Tuesday evening.
During a Thursday community meeting in Pierre Part, where state officials were not present, questions were raised about state agency transparency and the status of “fingerprint” tests on natural gas being released from area bayous and found in an underlying aquifer.
One man claimed the testing could be done in hours by industry, although the current testing has been going on for weeks.
Officials have been trying to see what could be source of the natural gas in the Bayou Corne area. The bubbles could be related to natural gas exploration and production activities in the area, for example.
Office of Conservation Commissioner Jim Welsh said Friday most forms of natural gas are “extremely simple compounds with minute differentiations” and they offer less criteria for analysis and comparison.
“Our top focus is identifying this natural gas so we can make the results available to the public and hold any contributing party accountable,” Welsh said in the statement.
“Because there are several different ways to read natural gas, these samples require specialized interpretation and, often, additional samples for expert analysis.”
While Illinois-based Isotech Laboratories was hired to analyze samples and is continuing the work, Welsh’s office has asked Shaw Group to hire an expert who has asked for additional data and analysis, the office news release said.
Results will be made available as soon as they are obtained, the news release said.
The sinkhole’s banks have occasionally collapsed as Texas Brine and DNR officials have predicted.
The latest collapse, or slough, happened Thursday on the east side of the sinkhole. Several trees were lost in the collapse that went out about 40 feet from the edge and took under about 1,000 square feet of earth, parish officials said in blog posts this week.
The prior collapse on Tuesday happened on the southwest corner of the sinkhole near a pipeline corridor and pulled down 4,000 square feet of dirt and trees, parish officials said.