The first fire broke out during welding on a crude oil pipeline and was immediately extinguished, the Iranian police information centre said.
The cause of the second inferno was not yet clear.
State television said firefighters had been battling the second blaze for more than 13 hours.
That fire, which broke out shortly before midnight Friday, was sparked by an explosion that killed one guard and injured two people.
The blazes occurred on the Mahshahr-Abadan oil and gas route, which comprises 13 pipelines carrying crude oil, gas and petrochemicals.
The public relations department of National Iranian South Oil Company said gas supplies to four cities in Khuzestan province had been cut.
