Factbox: Oil service companies in Venezuela

(Reuters) - Venezuela will nationalize a fleet of 11 oil rigs belonging to U.S. company Helmerich and Payne, the latest takeover in a push to socialism as President Hugo Chavez struggles with lower oil output and a recession.

A former soldier inspired by Cuba's Fidel Castro, Chavez has made energy nationalization the linchpin in his 'revolution'.

Chavez in 2007 nationalized multi-billion dollar projects in Venezuela's vast Orinoco oil region, persuading companies such as BP, to accept minority stakes in facilities.

Last year he ordered the takeover of dozens of smaller oil service companies as PDVSA, reeling from a sharp plunge in oil prices, struggled to pay contractors.

Following are some of the remaining oil service projects in Venezuela:

* Schlumberger Ltd: The world's largest oil service company is also a principal provider of services in Venezuela including drilling, measurement and well services designed to boost output of operations.

* Halliburton Co: A major player in Venezuela's oil services market, Halliburton provides products such as drilling fluids and a range of oil well services. Supporters of Chavez have frequently insulted the company for its association with former U.S. Vice President Dick Cheney despite it being a key PDVSA contractor.

* Petrex: Owned by a division of Italy's Eni, Petrex operates land rigs throughout Venezuela, mostly concentrated in the eastern region.

* Baker Hughes: The world's third-largest oil services company provides a range of oil field and oil well services in Venezuela.

* San Antonio Internacional: A land-based driller with a heavy presence in Latin American oil operations and a key driller in Venezuela.

* Other contractors operating in Venezuela include Danish shipping and oil group A.P. Moller-Maersk, BJ Services Co and Weatherford International Ltd.

(Reporting by Caracas newsroom)