Petrochemical plants continue to run as sun sets down in al-Jubail Industrial City, about 500km east of Riyadh, Saudi Arabia. Proven oil reserves in Saudi Arabia are the second largest claimed in the world, estimated to be 267 billion barrels.These reserves were the largest in the world until Venezuela announced they had increased their proven reserves to 297 Gbbl in January 2011.The Saudi reserves are about one-fifth of the world’s total conventional oil reserves.