By Meeyoung Cho and Seng Li Peng
SEOUL/SINGAPORE, Feb 5 (Reuters) - South Korea'ssecond-largest refiner, GS Caltex Corp, has hiked crude runrates to 93 percent of refining capacity, following a cut to 78percent after a weekend oil spill at sea caused by pipelinecracks, sources said on Wednesday.
The refiner, which has a capacity of 775,000 barrels per day(bpd), had slashed runs by 170,000 bpd over the past five daysbefore boosting the rate back to 710,000 to 720,000 bpd, asource familiar with the matter said.
The lower run rates were "inevitable" as supply had beensqueezed before the refiner received its next cargoes, he added.
Some 164,000 litres of oil leaked off South Korea's southerncoast after pipelines run by GS Caltex cracked last Friday at aquay off Yeosu, more than 300 km (185 miles) south of thecapital, Seoul, while the 318,445-deadweight-tonne Very LargeCrude Carrier Wu Yi San was approaching to offload crude.
Teams of workers aided by ships and aircraft have cleaned upthe waters but a cleanup of shore areas will take up to twoweeks. Oil remaining in the pipeline leaked, but none from thetanker, and GS Caltex said refining production was not affected.
The tanker, operated and managed by Singapore's OceanTankers, was chartered to Shell, Ocean Tankers said,adding that the two parties would discuss unloading options.
The tanker was carrying North Sea crude that had not yetbeen offloaded, said sources.
GS Caltex is equally owned by Chevron Corp, thesecond-largest U.S. oil company, and South Korea's GS Energy,owned by GS Holdings. Its refining complex is atYeosu.
In 2007, South Korea's worst oil spill occurred off thecoast of Taean, when 10,500 metric tonnes spilled from a HongKong-registered tanker whose hull was holed in a collision.
In November 2013, a small amount of oil leaked into the seaeast of South Korea from a cracked pipeline run by the country'stop refiner, SK Energy, owned by SK Innovation.