I don't really get this last part Heading Out:

"They will be used to produce relatively dry oil from the upper layers of the field, and to mix it with the oil and water coming from the rest of the field through the conventional vertical/inclined wells that go into the area that the water has already reached to maintain the overall water cut at around 42%."

Oh, sorry - basically (and you may need to go back to the pictures that Stuart posted ) the field is an inverted bow shape in section, and the water has come up on both sides so that only the center portion is still above the water flood. This oil is now being tapped using horizontal wells ,
as I tried to explain in the first Abqaiq post . The oil from those wells does not contain any water from the water floods, and thus I have called it "dry", while the water in the area where the wells go down into the water flood will also bring out some water (the water cut). Thus these are "wet" and it is by mixing the two that they are trying to stabilize their water cut at 42%.