great work joulesburn. the graph of pressure vs time shows that the reservoir pressure declined from about 2100 psi to around 1800 psi in the time frame shown. this probably gives a clue as to the slow developement of the field(s), given that heretofor, the saudi's had excess capacity.
what many probably dont realize is that with the relatively high reservoir temperature, these intermediate gravity oils are volitile under depletion. the upshot of which is that as pressure depletes, a mobile gas saturation developes and the gas/oil ratio rockets. having a high gas saturation at the start of waterflood can only lead to bad things. water displaces the low viscosity gas and leaves the higher viscosity oil behind, resulting in excess water production.
once again, it appears that aaramco is a good reservoir manager.
2 million bpd water injection against a peak primary of 140,000 bpd would lead to a disaster if the reservoir were depleted to a high gas saturation.