SAUDI ARABIA - The Main Fields Producing Heavier Oils.

Saudi Aramco's mothballed capacity for Arab Medium and Heavy crudes is limited to 1.8m b/d, down from to 3.2m b/d in 2001 and 4.87m b/d in late 1993. They include small offshore fields shut in and many wells closed in the larger fields. There will be a further mothballing of field capacities producing heavy crudes as additional fields, including those in the Najd area south of Riyadh, come on stream in the next few years.

Safaniyah, by far the largest offshore oilfield in the world, was found in 1951 by Texaco (which in 1937 was the first to join SoCal - now Chevron - in Saudi Arabia as a 50% partner in Aramco. But now Taxaco is part of Chevron). Texaco discovered and developed other offshore fields containing heavy oil.

Saudi Aramco announced on Aug. 17 the award of the first contract on the project to fabricate and install new pipelines, platforms and associated infrastructure at the three offshore oilfields of Safaniya, Zuluf and Marjan. Abu Dhabi-based National Petroleum Construction Co. (NPCC) got the EPC contract for the north Safaniyah artificial lift project. This entails supply and installation of 42 electric submersible pumps (ESPs) on seven existing platforms, the addition of mezzanine decks to the existing platforms, a 42-inch-diameter, 50-km main oil transfer line, a new tie-in platform, two 16-inch-diametre pipelines from the new platform to existing wellheads, four flexible pipelines, subsea power cables and communications facilities. The contract also calls for modifications to the Safaniya onshore GOSP.

A formal award was imminent recently for the second package, covering maintenance of potential facilities. Jebel Ali-based J Ray McDermott Middle East is the frontrunner for the EPC contract, which will involve fabrication and installation of five jackets, five decks and in-field pipelines over a total length of 18 km. Two subsea cables are to be installed at Marjan. Both EPC contracts are worth a total of $350-400m. WorleyParsons of Australia did the front-end engineering and design (FEED) work for both projects, which are aimed at increasing production capacity to 450,000 b/d from 300,000 b/d.

Safaniyah has over 15 bn barrels of proven oil reserves recoverable at relatively low cost. The oil is heavy, 27[degrees] API with 2.93-2.96% sulphur, and much of Safaniyah's 1.5m b/d capacity has been mothballed. Like most other offshore fields in the north-east, the oil is reservoired in Cretaceous sandstones and carbonates mainly at a depth of 5,100 ft.

(Texaco, once a crude-long major, sold 50% of its US East Coast system to Saudi Aramco in 1988. The resultant JV Star Enterprise made Texaco "crude-sufficient" as it gained a virtually permanent access to 630,000 b/d of Saudi crude oil. In 1997 Shell, Saudi Aramco and Texaco combined their assets into a new JV called Motiva Enterprise. On Oct. 9, 2001, as Chevron's takeover of Texaco was finalised, Saudi Aramco bought half of Texaco's stake in Motiva, with Shell buying the other half. Thus Motiva now is owned 50-50 by Saudi Aramco and Shell - see OMT 16).

In 1996, Saudi Aramco brought some of the mothballed desalting units and other facilities at Safaniyah back into operation. They enabled the company to handle more Arab Medium from the offshore Zuluf field. Reservoir pressure at Safaniyah, however, has begun to decline. Two rigs have been working continuously there to prevent a fall in production.

Zuluf, another offshore giant discovered by Texaco in 1968, has about 6.5 bn barrels of proven oil reserves in a Lower Cretaceous Fm at a depth of 5,800 ft. Its capacity is over 500,000 b/d, with another 200,000 b/d and two GOSPs mothballed. Saudi Aramco has planned to raise the field's capacity to 1.2m b/d. Of this a further 500,000-700,000 b/d has been earmarked for closure. Related facilities to upgrade the field's production of heavy crudes to Arab Medium grade have been built.