UPDATE 5-Ida's threat ebbs but US Gulf energy output disrupted

(For full coverage of Ida, click [ID:nN09265408])

* U.S. oil, gas production disrupted by Ida

* Ida downgraded from hurricane to tropical storm

* Schools closed, shelters opened on U.S. Gulf Coast (Recasts, updates storm position, adds details, quotes, previous HOUSTON)

By Kelly Dugan

MOBILE, Ala., Nov 9 (Reuters) - A weakened Tropical Storm Ida drenched the U.S. Gulf Coast and oil installations on Monday, shutting down nearly 30 percent of Gulf energy production.

Ida was expected to strike the coast near Mobile, Alabama, early on Tuesday. At one time a Category 2 hurricane, Ida's threat eased as winds dropped to 70 miles per hour (112 km per hour). They were expected to decrease further as the storm approached landfall.

A U.S. Coast Guard helicopter plucked two workers from a storm-damaged oil rig about 80 miles (130 km) south of New Orleans. Ida is blamed for 124 flood and mudslide deaths in El Salvador.

The Coast Guard closed the Port of Mobile, halting traffic on Mobile Bay, and authorities closed schools and government offices in coastal counties in Alabama and Florida, telling residents of flood-prone areas and mobile homes to evacuate.