The Petro Rabigh joint venture of state oil giant Saudi Aramco and Japan’s Sumitomo has acknowledged that construction of its Rabigh 2 expansion project will not be completed until the second quarter of 2017 with the anticipated total development cost now 10% higher than the previous figure.

Petro Rabigh says that while the majority of electrical and non-electrical utilities have been completed, new ethane cracker units have begun operating and cumene and phenol units are ready,...