Probe finds leaks before blast
Oklahoma drilling explosion preceded by fluid outpour that should have set off alarms, officials say
More than 100 barrels of drilling fluid — an amount that should have triggered alarms — poured out of a natural gas well before it ignited, killing five people at an Oklahoma site, federal investigators said Thursday.
The Chemical Safety and Hazard Investigation Board, probing the January explosion on a natural gas drilling rig near Quinton, Okla., said it found that 107 barrels of oil-based drilling mud flowed into the site’s mud pits between 7:57 and 8:35 a.m. Jan. 22.
Drilling mud is the fluid pumped down the drill pipe during drilling operation to cool the bit, remove particles and keep petroleum products such as natural gas from escaping the well hole.
That amount is far above the threshold of five to 10 barrels that triggers an alarm at oil and gas operations, indicating that natural gas had flooded the well at dangerous levels, said Lauren Grim, the board’s lead investigator.
The drilling fluids, pushed out of the well by the natural gas, started pouring from the blowout preventer, the safety device designed to prevent well explosions. Grim said it remains unclear whether it was minutes or seconds from the time workers noticed the surge in drilling fluids to the time of the explosion. The ignition source that led to the explosion and fire also is not known.
Brian Dunagan, chief investigator for the Houston safety and fire consultant IFO Group, said it appears the workers understood they had a problem with controlling the well and were trying to fix it. He noted that the company man — who oversees the site and would have the final word on shutting down the well — was in the control room at the time of the blast. The company man is typically on-site but not on the drilling rig unless a significant decision has to be made.
He added that a lack of experience may have played a role in the accident. That’s a problem that has plagued the oil field for years as experienced hands retire at high rates and young workers flood the booming industry, Du-
nagan said.
The investigation is expected to continue for several months. Kristen Kulinowski, interim executive director of the safety board, said the goal is to complete the investigation within 12 to 18 months of the accident.
The well fire and explosion, which occurred Jan. 22 near Quinton, Okla., about 100 miles southeast of Tulsa, was the deadliest U.S. accident in the oil and gas industry since 11 workers were killed in the 2010 Deepwater Horizon explosion in the Gulf of Mexico.
The drilling rig was owned by the Houston oil field services company Patterson-UTI Drilling, the main contractor for Red Mountain, a small Oklahoma oil and gas company operating the well.
In a statement released after the chemical safety board discussed its findings at a news conference in Oklahoma City, Patterson-UTI said it is cooperating with the investigation.
“We will be working with the (chemical safety board) to understand their potential recommendations when they are available at the conclusion of their investigation,” the company said. “We remain committed to providing a safe working environment for our employees and others we work with in the field.”
Michael Lyons, a Dallas attorney representing the family of Parker Waldridge, one of the men killed in the explosion, called the investigation “critical” for safety in the oil and gas industry.
“The (chemical safety board’s) investigation reveals, along with the independent investigation by my firm, that this tragedy was 100 percent preventable,” he said in a statement. “This disaster was the product of multiple failures to adhere to safe oilfield drilling practices.”
Oklahoma regulators said shortly after the explosion that their initial findings suggested that the blowout preventer — the same piece of equipment that failed in the Deepwater Horizon disaster — may have failed at the Red Mountain site. That equipment is usually the last line of defense to prevent a disaster.
Grim said it appears that one of the rams in the blowout preventer may have partially closed, but that further tests had to be conducted on the blowout preventer, which is in CSB’s possession. A ram is a piece of steel in the blowout preventer used to block and shut down a well.
In addition to Waldridge, the victims were Josh Ray of Fort Worth; Cody Risk of Wellington, Colo.; and Matt Smith and Roger Cunningham, both of Oklahoma. Ray, Smith and Risk were Patterson-UTI employees.
In July, the U.S. Occupational Safety and Health Administration said three companies — Patterson-UTI and two other contractors on the site, Crescent Consulting and Skyline Directional Drilling, both of Oklahoma City — face combined penalties of more than $118,000 for “exposing employees to fire and explosion hazards.”
“These employers failed to properly control hazards involved in oil and gas extraction activities, and the result was tragic,” said David Bates, director of OSHA’s Oklahoma City office, in a statement. “Employers are required to monitor their operations to ensure workplace health and safety procedures are adequate and effective.”
Patterson-UTI officials told the Associated Press that they disagreed with the finding and filed a notice of contest. A representative for Crescent Consulting declined to comment, and Skyline Directional Drilling did not respond to the AP’s requests for comment.