That impression, however, is a misleading one. Those impressed that the giant Tupi (now named Lula) Field area will eventually feature a minimum of nine floating production facilities in a phased development should be even more dazzled by the fact that Petrobras has already done much the same before—about two decades previously.

The Brazilian national oil company discovered its deepwater Marlim Field in the Campos Basin in 1985, a pioneering time seemingly far removed from the very necessary and highly public bloodletting that is taking place today as Operation Car Wash continues to clean out the cancer of endemic corruption that has infected Petrobras over the past decade or so.

Although the country’s offshore adventure began in the late 1960s in its shallower continental shelf waters followed by its more substantial discoveries during the 1970s in what was to become its Campos Basin heartland, it was its discoveries in the deeper areas of the Campos Basin in the mid-1980s that necessitated a step change in its approach to developing its resources.

Procap
Realizing that much of the technology that it needed to develop these deepwater fields simply didn’t exist, Petrobras set up its Procap program—an initiative that would eventually see it become a world leader in this area.

Many of the company’s major deepwater technology firsts took place on its 100%-operated Marlim Field complex, including the use of multiple floating production facilities, innovative subsea processing equipment and EOR techniques. Consisting of the field trio of Marlim, Marlim Leste (East) and Marlim Sul (South), they lie 110 km (68 miles) offshore Rio de Janeiro in water depths ranging from 610 m to 1,097 m (2,000 ft to 3,600 ft) in the northeastern part of the Campos Basin.

Marlim itself was found via exploration well 1-RJS-219-A in February 1985, with the probe encountering a 75-m (246-ft) thick Oligocene/Miocene turbidite reservoir covering an area of 137 sq km (56 sq miles). Holding an estimated 1.7 Bbbl of recoverable oil reserves (9 Bbbl oil in place), the field achieved a peak production of 586,315 bbl/d in 2002. Some 25 years after first oil was produced, Marlim is still pumping 390,000 bbl/d of oil.

Phased philosophy
To many observers Marlim perhaps best represents Petrobras’ proven philosophy of developing its larger offshore assets in a phased manner, something that it has since replicated many times over up to the present day.

In the case of Marlim, a pre-pilot phase was undertaken using the Petrobras 13 (P-13) floating production unit (FPU) to flow two wells in March 1991 to both get vital insight into how the reservoir would produce and earn some early income to help toward the larger main development costs. The P-13 produced for 14 months before being replaced by the P-20 floater.

The first true “Phase 1” was split into two modules. Module 1 in 1994 saw Petrobras build a new semisubmersible production platform, the P-18, which was installed in 910 m (2,986 ft) of water over the northern part of the field. The facility produces via 16 production wells and 12 water injection wells. This was assisted by a converted FPSO vessel, the P-32, complete with an oil dehydration plant and offloading facilities and a storage capacity of 100,000 bbl/d.

Module 2 also focused on the field’s northern area and saw a converted semisubmersible platform, the P-19, installed. Moored in 940 m (3,084 ft) of water, this facility has 12 production and seven water injection wells connected.

This was not all, as a further semisubmersible platform, the P-33, also was installed in the northeastern part of the field during the same “Module.” The P-33 came onstream in November 1998 via five satellite producer wells and three water injector wells.

The already-producing pilot phase vessel P-20 also was then selected to be retained as part of the permanent development.

Phase 2
Almost simultaneously, Petrobras also brought on Phase 2 of the project. Made up of three further modules, this phase targeted the central and southern areas of Marlim. Module 3 saw the converted P-26 semisubmersible production platform installed in 990 m (3,248 ft) of water, coming onstream in early 1998 with a processing capacity of 100,000 bbl/d of oil. It produces via 12 production wells and eight water injection wells.

An FPSO unit was again employed for Module 4, with the converted P-35 FPSO unit flowing as of May 1999 via 19 production wells and eight water injection wells tied back through two subsea manifolds. The turret-moored P-35 is located in 860 m (2,822 ft) of water and has a processing capacity of 100,000 bbl/d of oil.

The next millennium saw Module 5 get underway with the installation of another converted FPSO unit, the P-37, in 1999. Moored in 905 m (2,969 ft) of water, the floater has a processing capacity of 150,000 bbl/d and is connected to 20 production wells and 15 water injection wells via four subsea manifolds.

A floating storage and offloading unit, the P-47, was added to the field in 2005 to ramp up the field’s oil treatment capacity.

Although that was officially the end of the field’s original planned development program, Petrobras then went on just four years later to add a further three FPUs to the field almost simultaneously—the 180,000-bbl/d converted P-53 FPSO unit on Marlim Leste in November 2008; the 180,000-bbl/d newbuild P-51 semisubmersible unit that came onstream in January 2009 on Marlim Sul; and the leased 100,000-bbl/d FPSO Cidade de Niterói, again on the Marlim Leste Field, less than two months later. The latter is the deepest of them all in terms of depth, sited over the Jabuti reservoir in waters about 1,400 m (4,593 ft) deep.

These three units added a further 50 wells to the Marlim Complex’s total, 33 oil and gas producers and 17 water injectors.

Subsea world-first
Petrobras also has been proactive in employing innovative subsea technologies on Marlim, the most well-known being a world-first seabed separation system for deepwater heavy oil designed and built by FMC Technologies to help debottleneck production.

That $90 million contract saw the U.S. contractor supply a subsea module to separate the heavy oil, gas, sand and water at a water depth of 900 m (2,950 ft). The system reinjects the separated produced water to help counteract the mature field’s naturally declining reservoir pressure. That means Petrobras did not have to opt for the more conventional alternative, which would have been to flow all the liquids, including increasing amounts of produced water and sand, to the surface for separation there.

The subsea separation, pumping and reinjection system first separates the gas from the liquids, then deals with the water by using a pipe separator design licensed and developed by FMC in cooperation with Statoil. The separation module also is retrievable to the surface, according to the company, making its maintenance and replacement less costly and disruptive. The system also incorporates its proprietary InLine Hydro-Cyclone and DeSander modules for water treatment and sand management.

The separated gas is added back into the dewatered oil stream and sent on to the platform, while the treated water flows through the pump module for boosting and injection into the reservoir.

To a very real extent, Marlim has acted as a full-scale test bed for qualifying subsea separation equipment, a technology that is very much part of the industry’s own ongoing drive toward realizing seabed production factories.

With a fleet of 12 floating facilities still producing via about 150 subsea production and water injection wells, Marlim represents a world-class development that has spanned more than two decades of successful and safe operations.

Comments