FACTBOX - Oil companies check for damage after Gustav

(Reuters) - Oil companies are checking their oil rigs, refineries and pipelines for damage Tuesday, a day after Hurricane Gustav slammed the U.S. Gulf of Mexico coast in the first big storm threat to U.S. energy supplies since 2005.

Initial checks revealed only limited damage, though a huge chunk of the nation's oil and refining capacity was expected to remain offline for at least a couple of days.

The following outlines Gustav's impact on the energy sector:

***************************HIGHLIGHTS*************************

*100 percent of U.S. Gulf of Mexico oil output shut

*95.4 percent of U.S. Gulf natgas output shut

*33.7 percent of U.S. refining affected, 15.4 percent shut,

18.3 percent at reduced rates.

*1.1 million Louisiana, Mississippi customers without power, 32 percent of total - Department of Energy.

*Initial assessments reveal little or no platform, rig or

refinery damage, but considerable electrical damage.

*US waives gasoline standards in parts of Texas and

Louisiana, ready to release emergency crude

********************CRUDE OIL, NATURAL GAS********************

*100 percent of U.S. Gulf of Mexico's 1.3 million barrels

per day crude output shut as of Sunday, according to U.S.