"The reason for a decline in oil exports is a reduction in oil output at the Azeri, Chirag and Guneshli oilfields," a source at state energy company SOCAR told Reuters.
Natural gas exports rose to 5.649 billion cubic metres (bcm) from 4.983 bcm, the state customs service said.
Azerbaijan's oil production fell to 32.240 million tonnes in January-October from 34.718 million tonnes in the same period last year.
Natural gas output fell to 23.637 bcm from 24.609 bcm.
Azerbaijan exports oil via the Baku-Tbilisi-Ceyhan (BTC) pipeline from the Azeri, Chirag and Guneshli oilfields operated by BP.
It also exports oil via Russia, through the Baku-Novorossiisk pipeline and via Georgia by rail and through the Baku-Supsa pipeline.
Oil from Kazakhstan and Turkmenistan is also exported through the BTC.