Saudi is enormous - no doubt there are vast expanses completely away from civilisation, and I'm guessing there are plenty of remote oil field areas that are alr

Saudi is enormous - no doubt there are vast expanses completely away from civilisation, and I'm guessing there are plenty of remote oil field areas that are already degraded to some extent. However: firstly as you hint at the desert does have an ecosystem, and secondly salt is not the only contaminant in the sea. I could imagine an Aral Sea type scenario where heavy metals, for example, were evaporated out in significant concentrations over time. Then with a little wind blowing the dust towards populated areas, you are in trouble.