I wondered if someone else would get there before I had the time to complete my work. I'll try and parcel up where I've got to over the next few days so that others can use it. As a rough estimate, I've got the outline positioned to ~100 metre accuracy.

I have refined and reposted my Ghawar boundary overlay using a figure from the reference I cited in my original post above. Here is a screenshot of the overlay in GE:

I assume the authors of that paper had access to GIS data (they are from King Faud U.), although I look forward to your work as I am not close to 100m resolution with my tweaking.