A failure of two preventive barriers in place to stop a blowout were the main causes of a blowout and rig fire that killed five workers at the Pryor Trust gas well in Pittsburg County, OK, in January 2018, and while nothing will be able to bring back the victims, a new training video just released may help others from suffering a similar fate.
The Chemical Safety Board (CSB) just released a training video for the onshore drilling industry detailing lessons learned from the January 22, 2018, blowout and fire at the Pryor Trust gas well that fatally injured five workers.
On January 22, 2018, a blowout and rig fire occurred at Pryor Trust 0718 gas well number 1H-9, located in Pittsburg County, Oklahoma.
The fire killed five workers, who were inside the driller’s cabin on the rig floor, according to the CSB report. They died from thermal burn injuries and smoke and soot inhalation. The blowout occurred about three-and-a-half hours after removing drill pipe (“tripping”) out of the well.
Red Mountain Energy, LLC was the lease holder, Red Mountain Operating, LLC (RMO) was the operator of the well, and Patterson-UTI Drilling Company, LLC (Patterson) was the drilling contractor hired by RMO.
The cause of the blowout and rig fire was the failure of both the primary barrier — hydrostatic pressure produced by drilling mud — and the secondary barrier — human detection of influx and activation of the blowout preventer — which were intended to be in place to prevent a blowout.
Contributing to the loss of barriers were other factors including:
• Underbalanced drilling was performed without needed planning, equipment, skills, or procedures, thus nullifying the planned primary barrier to prevent gas influx.
• Tripping was performed out of the underbalanced well, which allowed a large amount of gas to enter the well.
• The driller was not effectively trained in using a new electronic trip sheet, which is used to help monitor for gas influx.
• Equipment was aligned differently than normal during the tripping operation, leading to confusion in interpreting the well data which caused rig workers to miss indications of the gas influx.
• Surface pressure was not identified two separate times before opening the BOP during operations before the blowout, when there was evidently pressure at the surface of the well. This non-identification of surface pressure contributed to the gas influx not being identified.
• A weighted pill intended to overbalance the well was apparently miscalculated. After pill placement, the well was still underbalanced.
• Both the day and night driller chose to turn off the entire alarm system, contributing to both drillers missing critical indications of the gas influx and imminent blowout. The alarm system also was not effectively designed to alert personnel to hazardous conditions during different operating states (e.g., drilling, tripping, circulating, and surface operations) and would have sounded excessive non-critical alarms during the 14 hours leading to the blowout, which likely led to the drillers choosing to turn off the alarm system.
• Key flow checks to determine if the well was flowing were not performed before the incident. Drilling rig workers performed very few of the company-required flow checks during the drilling of well 1H-9 and the previous well. The drilling contractor did not effectively monitor the implementation rate of its flow check policy.
• The drilling contractor did not test its drillers’ abilities in detecting indications of gas influx through, for example, simulated pit gains. The absence of testing drillers’ influx detection skills — a safety-critical aspect of well control — might have contributed to both drillers not detecting the significant gas influx leading to the blowout.
• The operating company did not specify the barriers required during operations, or how to respond if a barrier was lost. This contributed to the performance of underbalanced operations the drilling rig and its crew were not equipped or trained to perform.
• The safety management system in place was not effective for managing safe rig operations. There is also no drilling-specific regulatory standard governing onshore drilling safety.