Hydrogen Sulfide Accident at the Aghorn Operating Waterflood Station in Odessa, Texas-Final Report

Industrial Accidents
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May 15, 2021– The US Chemical Safety Board will be soon releasing its report into the Hydrogen Sulfide accident release incident at the Aghorn Operating Waterflood Station in Odessa, Texas. The incident occurred on October 26, 2019 and the investigation report was finally adopted by the CSB on May 4, 2021. Very soon the final report will be made available on the CSB website.

You can download the presentation from the May 4th public board meeting HERE.

What happened during the incident?

The Aghorn Operating waterflood station’s control system activated an oil level alarm on a pump. An Aghorn pumper was notified, drove to the waterflood station, and attempted to isolate the pump from the process by closing two valves. The CSB found, however, that the pumper did not isolate the pump from energy sources before performing the work. Isolating pumps before starting work should be part of any Lockout Tagout process before starting work, but this was not done.

(Note: To know quickly about Lockout Tagout, please see the explanation here.  To take a free Lockout Tagout course, please take a look at the Free LOTO training course here).

At some point while the pumper was in the vicinity of the pump, the pump automatically turned on, and water containing hydrogen sulfide escaped into the pump house. The pumper was overcome and fatally injured by the toxic gas, since H2S is a highly toxic gas, which is also explosive.

What is a Waterflood Station?

A waterflood station is used as part of a process to extract oil from underground pools of oil in West Texas. During the extraction process, oil gets mixed with groundwater. The water is removed from the oil, but it can contain some residual oil and other materials such as hydrogen sulfide (H2S), a toxic gas. Pumps are used to pressurize and inject the water back into the oilfield. The injected water adds pressure to the oil reservoir thus enabling larger amounts of oil to be extracted.

After the incident, the CSB found that a plunger on the pump had shattered, which had allowed the release to occur. Due to the limitations of the available evidence, the CSB was unable to determine whether the pump failure and toxic release happened before the pumper arrived at the facility, or when the pump automatically turned on while the pumper was closing valves.

What is Hydrogen Sulfide?

Hydrogen Sulfide (H2S) is a highly toxic gas which is commonly found in many oilfields. It is also known as “sour gas”. H2S is a poisonous gas which is also explosive and all oilfield workers, who may be working in a area that could have the presence of H2S, should be adequately trained regarding it.

What is a Hydrogen Sulfide accident?

A Hydrogen Sulfide accident happens when a worker or anybody else gets exposed to Hydrogen Sulfide and can get affected adversely.

Unfortunately many people do not take the H2S training and hence may be the victims of a Hydrogen Sulfide accident.

Note: You can take the free Hydrogen Sulfide training course here to learn more about it.

Summary of CSB findings regarding the Hydrogen Sulfide accident

  • Nonuse of Personal Hydrogen Sulfide Detector
  • Nonperformance of Lockout / Tagout (LOTO for short)
  • Confinement of Hydrogen Sulfide Inside Pump House
  • Lack of any Safety Management Program
  • Nonfunctioning Hydrogen Sulfide Gas Detection and Alarm System
  • Deficient Site Security

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