HOUSTON, Aug 14 (Reuters) - Exxon Mobil on Monday for the first time registered arbitration awards against Venezuela with a U.S. federal court in Delaware that soon plans an auction of shares in Venezuela-owned oil refiner Citgo Petroleum.

The oil major had not previously participated in the case brought by miner Crystallex International, which has drawn at least a dozen other companies seeking to attach their claims, some for the first time. Monday was the deadline to notify the court about claims to be considered.

An Exxon spokesperson did not have an immediate reply to a request for comment.

Exxon's oil projects Cerro Negro and La Ceiba were expropriated in 2007 by Venezuela's late President Hugo Chavez, which led to lengthy international arbitration cases.

Exxon listed three awards it has won since 2007 -- $179 for La Ceiba, $1.4 billion for Cerro Negro and another $9 million for production and export curtailments at Cerro Negro. A portion of the claims have been paid over time.

Following a July decision by the World Bank's International Center for Settlement of Investment Disputes (ICSID), Exxon said it was granted $984.5 million in compensation plus $1.02 million in costs and fees. (Reporting by Marianna Parraga; Editing by David Gregorio)