Scientifically, Can some one explain why most of the world's oil reserves are located in Middle-East?

in ancient times, most of the Middle East are forest, rivers or swamps. As ages go by, the accumulated detritus of the organisms that died in that forests, rivers and swamps was buried together and then heated, compressed and then stored for millions of years.Scientifically, Can some one explain why most of the world's oil reserves are located in Middle-East?
There can be just one reason, the world's major oceans were located there eons ago.