Oil companies have resumed work along the US Gulf Coast after Hurricane Isaac forced the shutdown of 94% of oil and gas operations.

Crews are returning to their platforms as power is restored and floodwaters are cleared out.

Onshore pipelines, ports and terminals have reopened, although they are operating with restrictions. Some sections of Shell’s offshore pipeline network have restarted, and others are expected to restart in the next few days.

The US Energy Department said that nine refineries in the path of Isaac have resumed operations at reduced rates, but Phillips 66’s plant in Belle Chasse, Louisiana is still without electricity, reports the Associated Press.

Oil and gas production remains down by 800,000 barrels per day, amounting to a 58% loss, according to the Bureau of Safety and Environmental Enforcement.

Based on data from offshore operator reports submitted on September 3, personnel were been evacuated from a total of 71 production platforms, the equivalent to 11.91% of the 596 manned platforms in the Gulf of Mexico, as the Hurricane approached .

As part of the evacuation process, personnel activate the applicable shut-in procedure, which can be accomplished from a remote location. This involves closing the sub-surface safety valves located below the surface of the ocean floor to prevent the release of oil or gas.

Image: Hurricane Isaac moving toward the Gulf Coast. Photo courtesy of: NOAA.