The Abqaiq processing plant was hit at the weekend. It processes crude from the Ghawar, Shaybah and Khurais fields that produce Arab Light or Arab Extra Light.
Bapco shut down a 22,000 bpd crude distillation unit at its Sitrah refinery on Monday, according to an alert sent to clients from research company IIR.
Another 22,000 bpd CDU, 10,200 bpd Vacuum Distillation Unit 1 and 24,000 bpd Visbreaker Unit had to reduce run rates to 45 percent.
Saudi state oil firm Aramco and Bapco did not immediately respond to a request for comment.
(Reporting by Rania El Gamal and Julia Payne, additional reporting by Ahmad Ghaddar; editing by Ghaida Ghantous and Angus MacSwan) (([email protected]; +971 562 160 434; Reuters Messaging: [email protected] ; Twitter: https://twitter.com/Rania_ElGamal))