A new report from the US Bureau of Safety and Environmental Enforcement (BSEE) blamed the crew working Walter Oil & Gas’ South Timbalier Block 220 Well A-3, 55mi off Louisiana, for a well control incident that caused a blowout and fire onboard Hercules Offshore’s jackup MODU Hercules 265 in July 2013.
At the time of the incident, completions operations were underway on a sidetrack well in preparation for production when natural gas flowing form the well ignited and spread to the rig. Forty-four workers onboard at the time had to be evacuated.
The BSEE report states that the panel, which investigated the 2013 incident, found that Walter and Hercules personnel did not calculate the density of the zinc bromide completion fluid used to maintain a pressure balance within the well. The panel concluded that the crew encountered temperatures higher than expected, which affected the density of the completion fluid. As a result, the completion fluid did not effectively maintain the pressure balance in the well, which resulted in the flow of hydrocarbons into the well.
Additionally, BSEE’s report said the crew missed signs of a kick in its early stages. “Crew on the rig floor only became aware that the kick occurred when completion fluid began to shoot out from the open end of the annulus and drill pipe. With the zinc bromide fluid raining down on them, the crew began to have difficulty working as the fluid caused a burning sensation to their eyes and skin. This exposure accounted for the minor injuries reported by the crew. The panel concluded that the procedures in place for responding to a loss of well control were inadequate because they did not consider the potential caustic effects of the completion fluid on the crew.”
BSEE’s report further stated that the force of the fluid moving out of the well was strong enough to push the drill pipe upward and into the top drive. The crew could not manipulate the drill pipe, which prevented them from installing the drill pipe safety valve and further limited their options of reestablishing control of the well.
The panel found the actions to close the rams came too late; by the time the attempt to close was made, the well was already flowing at a pressure exceeding the BOP’s capabilities. The flow of gas up through the well also carried sand from within the formation. This mixture of gas and sand travelling at high velocity quickly eroded the surfaces within the BOP, which would have prevented any chance of maintaining a proper seal. When the BOP stack was recovered from the rig, the panel was able to document evidence of this sand cutting on the BOP.
Gas flowed from the well for over 13 hours, before igniting and burning for another two days. BSEE’s report said the prolonged burning led to bending of the steel beams that supported the drill floor and derrick, which was directly over the well. The derrick and significant portions of the drill floor collapsed into the water, with the remainder of the Hercules 265 sustaining heat and smoke damage. The flow of gas eventually stopped as a result of the natural accumulation of sediment inside the well. A relief well was ultimately drilled to relieve pressure and gain control of the A-3 well using the Rowan EXL-3 jackup rig. The relief well was spud on 3 August 2013.
BSEE Director Brian Salerno said in response to the panel report that this incident bares similiarities to other blowouts on the Outer Continental Shelf. "Given these equipment and human failures noted in the report, this incident could have easily resulted in a more tragic outcome, and must be viewed as very serious," he warned.
In 2013, after a series of incidents in shallow water from 2012-2013, representatives from BSEE, US Bureau of Land and Mineral Management, and the Department of the Interior met to discuss the need for improved safety concerns. Former BSEE Director James A. Watson made a point about shallow water drilling that remains particularly important.
"While many consider shallow water operations to be less technically challenging than those occurring in deepwater, they are not without risk,” Watson said. “Offshore workers need to be empowered to take actions to save lives when they see a leading indicator that something is wrong.”
The full BSEE investigation report on the South Timbalier 220 incident can be viewed here.
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