FACTBOX-Arbitration cases against Venezuela nationalizations

Dec 1 (Reuters) - Venezuela is battling more than a dozen arbitration cases triggered by a wave of nationalizations by President Hugo Chavez's socialist government.

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

* Exxon Mobil Corp brought its case in October 2007, shortly after Venezuela took over the Cerro Negro upgrader the U.S. company was operating in the Orinoco heavy crude belt, as well as exploration acreage in the western La Ceiba block.

In early 2008, Exxon asked a British court to freeze $12 billion of PDVSA's overseas assets in lieu of compensation. Chavez threatened to cut oil exports to the United States in retaliation, before the British court rejected the request.

* ConocoPhillips also brought a major case in 2007, but is 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. Venezuela says it expects rulings in both cases by the end of 2011.

* Two cement companies, Mexico's Cemex and Switzerland's Holcim , 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 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 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 last April 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 this year, 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.