More than 48% of natural gas production from the U.S. Gulf of Mexico (GOM) was shut in Monday as Tropical Storm Isaac, its projected path veering further west over the weekend and its power expected to increase to hurricane strength within the next 24 hours, moved ever closer to New Orleans.

The relevance of Isaac's path and timing is not lost on the people of the Gulf Coast nor the energy industry as the seven-year anniversary of the devastating landfall of Hurricane Katrina nears. Katrina, a Category 3 hurricane at landfall, hit the Gulf Coast on Aug. 29, 2005 (see Daily GPI, Aug. 30, 2005). Combined with a double punch from Hurricane Rita, the two storms destroyed a significant amount of oil and gas infrastructure in the GOM and shut-in hundreds of Bcf and millions of barrels of oil (see Daily GPI, June 12, 2006).

AccuWeather.com forecasters noted that Katrina moved up from the south over the Mississippi Delta on a curved path, while Isaac is likely to be rolling in straight from the southeast, so the counterclockwise flow around the storm could drive a significant surge toward Louisiana's Chandeleur Sound, Lake Borgne and Lake Pontchartrain early on.

"While from a core meteorological standpoint Isaac will not be another Katrina in terms of intensity, it is still a dangerous storm," said AccuWeather.com meteorologist Alex Sosnowski.

Based on data from offshore operator reports submitted to the Bureau of Safety and Environmental Enforcement (BSEE) by 11:30 a.m. CDT Monday, personnel had been evacuated from a total of 346 production platforms, equivalent to 58% of the 596 manned platforms in the GOM. Personnel had been evacuated from 41 rigs, equivalent to 54% of the 76 rigs currently operating in the Gulf.

"From operator reports, it is estimated that approximately 78.02% of the current daily oil production in the Gulf of Mexico has been shut-in. It is also estimated that approximately 48.13% of the current daily natural gas production in the Gulf of Mexico has been shut-in," BSEE said.

At 5 p.m. EDT Monday the National Hurricane Center (NHC) said Isaac was located about 255 miles southeast of the mouth of the Mississippi River, moving northwest at 12 mph, and the center of the storm was expected to approach the Gulf Coast south-southeast of New Orleans Tuesday. Isaac's maximum sustained winds had increased to 70 mph and it was expected to become a hurricane Monday night or early Tuesday, NHC said.

A hurricane warning was in effect east of Morgan City, LA, to the Alabama-Florida border, and a hurricane watch was in effect from Intracoastal City, LA, to Morgan City, LA. A tropical storm watch was in effect as far west as Sabine Pass on the Texas-Louisiana border.

Anadarko Petroleum Corp. on Monday said it had removed all personnel -- about 160 workers -- from its operated facilities in the central and eastern GOM. Shut-in facilities included Anadarko's Independence Hub, Constitution, Marco Polo, Red Hawk, Neptune and Gunnison deepwater platforms.

Royal Dutch Shell plc, which had been evacuating workers from its facilities in the eastern GOM beginning over the weekend, said Monday afternoon that its manufacturing facilities at Norco, Convent and Geismar, LA. and Mobile, AL were operating at reduced rates, "consistent with pre-established hurricane preparation plans." In addition, the Shell-operated Capline pipeline was shut down Sunday evening.

ConocoPhillips said it had shut in all production at the Magnolia platform by Sunday afternoon and had expected to have all personnel evacuated from the 5,000 boe/d platform by Monday morning.

Chevron Corp. had evacuated personnel from offshore facilities and some production had been affected due to third-party pipeline closures. "At our onshore facilities, we are following our storm preparedness procedures and paying close attention to the track and forecast of the storm," Chevron said. "Our Pascagoula [Mississippi] refinery continues to operate."

BP plc began shutting in production and evacuating all workers from its Thunder Horse oil and gas platform in the Mississippi Canyon area south of Louisiana and evacuating nonessential workers from the Na Kika, Horn Mountain and Marlin platforms last Friday (see Daily GPI, Aug. 27). Nearly 300 people work on Thunder Horse, which is the largest deepwater production unit in the world, with capacity to process up to 200 MMcf/d of gas and 250,000 b/d of oil.

On Monday BP said it had evacuated all personnel from its production platforms and oil and gas production suspended at all of its GOM facilities. "All BP operated drilling rigs have been evacuated or are securing to evade the storm," said a spokesman. "In addition, BP's onshore facilities in Houma [LA], Fourchon [LA] and in Pascagoula [MS] are being evacuated. Other Gulf Coast facilities had begun preparations for the possibility of the storm effecting their sites, BP said.

Apache Corp., which had evacuated nonessential personnel in the eastern GOM "as a precautionary measure" on Friday, ordered further evacuations and some production shut-ins at its operations in the eastern GOM on Sunday. "In all, about 750 employees and contractors have been evacuated from the company's facilities in the eastern Gulf," Apache said. "Operated production totaling about 24,000 b/d of oil and 91 MMcf/d of gas has been or will be curtailed by day's end in anticipation of the possible approach of Tropical Storm Isaac."

Tennessee Gas Pipeline Co. on Monday said it had shut in 350,000-400,000 Dth of production and reported that Targa's Yscloskey processing plant in Louisiana was being shuttered. "The current interruption in supply has not had any significant operational impact on meeting Tennessee's customer obligations," according to the company, which asked customers to reduce nominations at meters impacted by Tropical Storm Isaac on the next available scheduling cycle.

Louisiana Offshore Oil Port (LOOP) announced Monday that tanker unloading at the marine terminal was suspended and workers evacuated to onshore facilities. Deliveries were still being made from LOOP's onshore storage facilities.

Southern Natural Gas Co. said it had been forced to shut in facilities at Toca, LA, and upstream of Toca and declared a force majeure "due to mandatory evacuations as a result of Tropical Storm Isaac."

Transcontinental Gas Pipe Line said Monday its Southeast Louisiana Lateral would be isolated and shut in near Gibson, LA. "As of 1 p.m. [Monday] approximately 500 MMcf scheduled to flow to Transco has been shut in," said a Transco spokesman. In addition, Transco reported that natural gas liquid processing facilities on the Mobile Bay Lateral were shutting down. Mississippi Canyon Gas Pipeline LLC also reportedly declared force majeure on its 800 MMcf/d system Sunday, cutting receipt and delivery flows to zero until further notice.

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