The South American OPEC member nation is battling more than a dozen such cases triggered by a wave of nationalizations by President Hugo Chavez's socialist government.

Most of the proceedings are being handled by the World Bank's International Center for Settlement on Investment Disputes (ICSID). Below are details of the main cases it is considering:

* ConocoPhillips (>> ConocoPhillips) brought a major arbitration case in 2007 against Venezuela, seeking $30 billion in compensation for stakes in two Orinoco projects - Petrozuata and Hamaca - and two joint venture exploration agreements in the Gulf of Paria.

* Two cement companies, Mexico's Cemex (>> Cemex SAB de CV) and Switzerland's Holcim (>> Holcim Ltd), requested ICSID arbitration after Chavez's government took over the industry in 2008. They claimed a total of about $2 billion in compensation. Venezuela said in November 2011 it had agreed to pay Cemex $600 million.

* Canadian miner Gold Reserve Inc (>> Gold Reserve Inc.) filed for arbitration in late 2009 after the authorities seized its Brisas project, which sits on one of Latin America's largest gold veins. Canada's Vanessa Ventures has a similar claim from 2004 for a $1 billion-plus project.

* U.S.-based oil service provider Tidewater Inc (>> Tidewater Inc.) has petitioned ICSID and is hoping for about $45 million in compensation after Chavez's government expropriated the assets of 76 service companies in May 2009.

* Universal Compression International Holdings, owned by U.S. company Exterran Holdings Inc, was another company hit by the wave of oil service nationalizations in 2009. It requested arbitration over $400 million in assets.

* OPIC Karimum, a subsidiary of Taiwanese state oil company CPC Corp , filed another case last June against Venezuela. OPIC had a minority stake in projects in the Gulf of Paria.

* In February 2011, Canadian gold miner Crystallex International Corp filed a demand for $3.8 billion, saying the Chavez government had unilaterally ended its contract for the huge Las Cristinas project. (Source: Reuters reports and http://www.worldbank.org/icsid)

(Reporting by Caracas Newsroom; Editing by Bill Trott)