About Northern Area Technical Support Department?

I would like to apply a position which is related to corrosion.
It says "Northern Area Corrosion and Inspection Division under the Northern Area Technical Support Department".
I really wonder where it is located, nearby Ras Tanura or Dhahran.

I know that a head office is located in Darhran, so that most engineers work at Dhahran main offce? and Especially, a corrosion or inspection engineer usually work at Dhahran, also or where?
It can depend on a position but trivical info helps me a lot
That's important before applying.

Thanks in advance.