What Happened
What Happened
On November 15, 2023, about 7:00 p.m. local time, an 18-inch underwater crude oil pipeline released about 1.1 million gallons of crude oil into an unusually sensitive area in Main Pass 69 in the Gulf of America, southeast of Venice, Louisiana, in Louisiana state waters. The pipeline is part of the Main Pass Oil Gathering (MPOG) pipeline system, owned by Houston, Texas–based midstream company Third Coast Infrastructure LLC and operated by affiliate Panther Operating Company.2 The weather at the time of the accident was 73°F with light rain and east-northeast winds of 41 mph with 48-mph gusts. No injuries were reported, and the crude oil did not ignite.
What We Found
What We Found
We determined the probable cause of the 18-inch diameter Main Pass Oil Gathering pipeline crude oil release was the loss of seal in a collet grip pipeline fitting from pipeline movement caused by geohazards that had not been addressed previously by Third Coast’s insufficient integrity management program.
Contributing to the volume of crude oil released was an inappropriate control room response that did not shut down the pipeline system because of the controller’s uncertainty about the accuracy of data from a supervisory control and data acquisition system that indicated but did not alert the operator of a leak for more than 11 hours.
What We Recommended
Pipeline operators must manage and address all threats to pipeline integrity, including those from weather events and geohazards. After the accident, Third Coast developed a program to monitor the MPOG pipeline system and collet grip fittings for possible pipe movement and to test and confirm the function of the fitting seals. PHMSA is overseeing modifications to Third Coast’s risk management program to include evaluations when mudflows or other geohazards occur.
In this accident, uncertainty about the accuracy of the supervisory control and data acquisition (SCADA) system data led to a delayed shutdown of the pipeline. The NTSB has investigated other accidents in which controllers, faced with control system information indicating an anomaly, have failed to shut down pipelines. In Marshall, Michigan, in 2010, controllers’ flawed interpretations of system data and alarms contributed to the delayed shutdown of a pipeline, which released 843,000 gallons of crude oil into wetlands. More recently, in 2021, pipeline controllers in San Pedro Bay, near Huntington Beach, California, did not shut down a leaking underwater crude oil pipeline for 14 hours after incorrectly determining that leak alarms were false.
Leak detection tools help reduce uncertainty for controllers interpreting abnormal control system data. After the accident, Third Coast reported that it is implementing a leak detection software system specifically for MPOG and has added a leak detection alarm to its SCADA system, with a tolerance level based on historical flow patterns. The company also added information on leak detection to its control center operational procedures and related training.
