Its interesting that your saying injected water in Ghawar is traveling this far ?

How big is the hydraulically connect region underlying Ghawar ?

I guess this would be the entire Arab D formation ?

As the Arab-D is sandwiched between two rather impermeable formations (Hith and Jubaila), it seems reasonable that static pressure would transmit rather far. But as to how much water flow could be expected, I have no idea. And I am skeptical that all those wells are going to be driven by injection-at-a-distance.

You motivated me to look one more time, and it does seem that they might be putting water injectors on the east side of the field (at least). See addendum at the end of the article.