Oil traders are spotting oil refinery trouble by tracking phones

Workers prepare drilling pipe on the Petroleos Mexicanos (Pemex) La Muralla IV deep sea crude oil platform in the waters off Veracruz, Mexico, on Friday, Aug. 30, 2013.  Photographer: Susana Gonzalez/Bloomberg
Workers prepare drilling pipe on the Petroleos Mexicanos (Pemex) La Muralla IV deep sea crude oil platform in the waters off Veracruz, Mexico, on Friday, Aug. 30, 2013. Photographer: Susana Gonzalez/Bloomberg

Breaking