HOUSTON/NEW YORK (Reuters) - BP (>> BP plc) has booked at least two new tankers to transport U.S. crude in May to a terminal operated by Venezuela's state-run oil company PDVSA in the Caribbean after sending five cargoes in April, according to traders and Thomson Reuters data on Monday.

The shipments will carry West Texas Intermediate crude, though initially the British oil company had scheduled to deliver 2.7 million barrels of Nigerian crude to Curacao to fill a Petroleos de Venezuela (PDVSA) tender to import some 8 million barrels of oil in the second quarter, the data show.

The cargoes will set sail after the U.S. crude export arbitrage window was closed over the past week, with U.S. futures trading on Monday at its widest premium over Brent since the start of the year.

U.S. WTI also settled above Brent in all futures contracts through November on Monday.

BP likely hedged the sales in April, traders said, when the window was open with Brent's premium over U.S. crude at its widest since mid-February.

As a result, a number of large oil companies rushed to buy calendar-spread options (CSO), betting that tightening supplies and resurgent exports would boost the market.  

BP has sent at least five 550,000-barrel cargoes of WTI crude from the U.S. Gulf Coast to Bullenbay terminal in Curacao since March, when it was awarded PDVSA's tender for 5.4 million barrels of light oil.

A second winner of the same tender, China National Petroleum Corp [CNPET.UL] unit China Oil, is supposed to deliver a total of 2.7 million barrels more to PDVSA in the second quarter. It has shipped two U.S. crude cargoes since April.

PDVSA's tender has a provision saying the buyer can choose whether to deliver U.S. or Nigerian grades during the specified period. The oil is partially being processed at the company's refining network and is also being used as diluent for Venezuela's extra heavy oil output, according to PDVSA shipping data.

Nigerian crude available for spot sales is limited. Threats from militants led Royal Dutch Shell to evacuate workers this week at Nigeria's Bonga oil field in the southern Niger Delta, following attacks last week that forced Chevron (>> Chevron Corporation) to close an offshore facility, affecting 35,000 barrels per day (bpd) of production.

PDVSA is facing delays loading and discharging tankers at its main crude port due to equipment malfunctions that are causing a backlog of vessels in the Caribbean. BP and China Oil have only been able to discharge two of seven cargoes sent to Curacao since April.

(Reporting by Marianna Parraga in Houston and Jarrett Renshaw and Catherine Ngai in New York; Editing by Terry Wade and Richard Chang)