CSB adopts report on lethal release of hydrogen sulfide (H2S)
On May 4, the United States Chemical Safety and Hazard Investigation Board (CSB) adopted a final report on a release of hydrogen sulfide (H2S) on October 26, 2019 at the Aghorn Operating flood station in Odessa , in Texas. The release of poisonous gas fatally injured an Aghorn employee who worked in the establishment, as well as his wife, who attempted to locate him in the establishment after he did not return home.
The CSB made several recommendations to the employer, but also recommended that the Occupational Safety and Health Administration (OSHA) issue a safety alert or safety bulletin addressing the requirements for the control of hazardous energy. (lockout / tagout) to protect workers from hazardous air contaminants such as H2S.
Water injection, or “waterflooding”, is used to increase the volume of oil extracted from an oil tank. At the Aghorn site, pumps from a building called a “pumping station” are used to pressurize and inject water into the oilfield, adding pressure to the reservoir. Water is removed from the extracted oil, but the water can contain contaminants such as toxic H2S gas, as well as residual oil.
“Water injection stations are common throughout Texas,” CSB president Katherine Lemos said in a board statement. “The CSB report determined that additional protective measures are needed to ensure that a similar event is avoided.”
CSB investigators Lauren Grim and William Hougland identified several safety issues at the Aghorn facility, including the failure to use a personal H2S detector; lack of lockout / tagout policies or procedures; lack of adequate ventilation in the pumping station, confining toxic H2S inside the building; the absence of a formal corporate safety management program; a non-functioning H2S detection and alarm system; and poor site security.
Investigators found that on the night of the incident, the flood station control system had activated an oil level alarm on a pump. An Aghorn pumper has been notified. He then went to the water injection station and attempted to isolate the pump from the process by closing two valves.
The CSB found that the pump had not performed a lockout procedure to isolate the pump from energy sources prior to performing the work. While the pump was near the pump, it automatically turned on and water containing H2S escaped into the pumping station. The pump was overturned and fatally injured by the poison gas.
However, board investigators could not determine whether the pump failure and toxic release occurred before the pump arrived at the facility or when the pump automatically turned on while the pump was in operation. pump closed the valves.
When the pumper did not return home, his wife went with their two children to the station to watch him. She located it on the floor of the pumping station and was also defeated and fatally injured by the poisonous H2S gas. The children remained in the car and were not injured.
The CSB has several recommendations to Aghorn Operating, Inc .:
- Make the use of personal H2S detection devices compulsory.
- Develop a site-specific, formalized and comprehensive locking / tagging program for each installation.
- Order a complete, independent scan of each facility to examine ventilation and mitigation systems.
- Develop and demonstrate the use of a safety management program that emphasizes the protection of workers and non-employees from H2S.
- Ensure that H2S detection and alarm systems are properly maintained and configured, and develop site specific detection and alarm programs and procedures.
- Ensure that H2S detection and alarm systems use multiple layers of alerts unique to H2S.
- Develop and implement a formal, written, site-specific security program to prevent the unknown and unplanned entry of non-employees.
The CSB also recommended that the Railroad Commission of Texas develop and send a notice to all oil and gas operators under its jurisdiction outlining the safety issues identified in the CSB report.
The text of the final report will be released in a few weeks, but the presentation for the board is available on the board’s website.