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. 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.

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.

KEY ISSUES:
• POOR BARRIER MANAGEMENT
• UNDERBALANCED OPERATIONS PERFORMED WITHOUT PROPER PLANNING, PROCEDURES, OR NEEDED EQUIPMENT
• SIGNS OF INFLUX EITHER NOT IDENTIFIED OR INADEQUATELY RESPONDED TO
• ALARM SYSTEM OFF
• FLOW CHECKS NOT CONDUCTED
• GAPS IN SAFETY MANAGEMENT SYSTEM
• DRILLER’S CABIN DESIGN
• BOP COULD NOT CLOSE DUE TO BURNED HYDRAULIC HOSES
• LACK OF SAFETY REQUIREMENTS BY REGULATION

ROOT CAUSES:
1. Failure of primary barrier – hydrostatic pressure produced by drilling mud.
2. Failure of secondary barrier – human detection of influx and activation of the blowout preventer.

Image & AcciMap Credit: CSB

Image credit: CSB