NEW YORK, Sept 13 (Reuters) - The U.S. Energy Information Administration on Thursday said Hurricane Isaac caused "considerable disruption" but little damage to natural gas processing plants along the U.S. Gulf of Mexico coast when the storm came ashore three weeks ago.
The EIA in its Today in Energy report said it invoked an emergency-activation survey to collect daily data on the status of plant operations in the affected area after Isaac came ashore on Aug. 28.
Despite the disruption as well as shut-in offshore gas production, there were few reports of damage to energy infrastructure from the low-level Category 1 hurricane.
There was also little effect on natural gas prices due to ample onshore production and surplus storage, the EIA said.
The last time the EIA invoked the activation survey, Form EIA-757B, was for Hurricane Ike in September and October 2008.
Isaac disrupted natural gas processing operations for more than 10 of the 13.5 billion cubic feet per day of total processing capacity in the area. On Sept. 7, a chart showed shut-in processing capacity was less than 4 bcf per day.
The survey captured plants with capacities greater than 100 million cubic feet per day.
Prior to Isaac making landfall, there were 25 natural gas processing plants in the affected area that were not undergoing maintenance, accounting for 12.6 bcf per day of available processing capacity.
Widespread power outages affecting nearly 1 million customers in Louisiana following the storm reduced the need for gas supplies, while the potential for flooding reduced or curtailed operations at many of the plants.
Plants most commonly attributed closures to a lack of upstream supply, although a few also cited damage to downstream infrastructure that would receive their dry gas or their natural gas liquids products, the EIA said.
Processing facilities purify and "dry out" raw natural gas from producing wells. This process results in pipeline-quality natural gas for delivery to end-users and a mix of natural gas liquids products to be separated by fractionators.
The Department of Interior's Bureau of Safety and Environmental Enforcement's final update on Isaac was released on Tuesday. The report showed that less than 5 percent, or 213 million cubic feet, of Gulf of Mexico gas production remained shut in.
At the height of the outages in late August, the storm had shut more than 70 percent, or more than 3.26 billion cubic feet, of daily offshore gas production.
The U.S. Gulf of Mexico has accounted for a progressively smaller share of U.S. gas production in recent years due to steadily declining offshore production volumes in the Gulf and the prolific growth of shale gas production in various onshore basins. (Reporting by Eileen Houlihan; Editing by Marguerita Choy)