Thirteen Years Made Short (1973–86)

Until shortly before the 1973 oil price increase, offshore activity was in its earliest stages: at that time only large fields were considered to be economically feasible for exploitation. In 1979, large platforms made their debut in the North Sea in the Ekofisk, Frigg, Brent, Piper, Forties, Ninian, Statfjord and Beril fields and, in the USA, in the Cognac and Hondo fields.

To cope with the tight economics of small reservoir discoveries, the Early Production System (EPS)/Floating Production Systems (FPS) concept arose independently in Argyll (1975) in the North Sea, Enchova (1977) in Brasil, Castellon (1979) in the Spanish Mediterranean, and later in various other fields such as the Garoupa-Namorado one atmosphere EPS, and the Pampo, Dourado, Casablanca, Cadlao, Buchan, Bicudo, Badejo and Tazerka wet completions. The 1970s were doubtlessly the era when reality caught up with imagination and when exploration, drilling and exploitation techniques made a gigantic technological step moving to deeper and deeper offshore fields.

Deep Water Means…

Before and during the 1970s, anything beyond 100 m W.D. was included under the heading "deep waters". The evolution of saturated diving techniques as well as remote operated vehicles (ROVs), electronic remote control systems, connectors, etc., made the 100 m figure change to the present approximately 300 m diving limit.

There are already diving companies experimenting with different gas mixes and testing as deep as 400–500 m, as well as off-the-shelf commercially available ROVs that operate at depths in excess of 1000 m. In Brasil, Petrobras presently considers "deep waters" to start at 300 m, though it is expected that saturated diving depth limits could reach 420 m with no significant technological changes.

Floating Production Systems

Though pushed by the oil price increase, the offshore oil industry move to deeper waters put at constant risk the economic feasibility of (up to then) well proven engineering solutions. Exploring, drilling and exploiting techniques used for 100 m water depths were simply not usable (as they were) at 500 m: technical and economical barriers proved to be hard to overcome.

One of the results of the above-mentioned feasibility red light was the startling development of not only more complex and at the same time more reliable subsea equipment, but also new ideas and concepts regarding offshore and subsea transportation, installation, operating and maintenance techniques and procedures. In the Southern Hemisphere Petrobras is actively participating in this breakthrough. A good example of this evolution is the Early Production System (EPS): Petrobras has been one of the very first oil companies to test this concept and intend to make intensive use of it in the development of deepwater fields.

The first Petrobras subsea completion was approved by the board of directors in 1975 it was the Garoupa-Namorado one atmosphere EPS, with chambers installed in W.D. varying in the range of 120–160 m, plus a dry-manifold and two tanker-mooring towers (one for a converted processing ship and the other for the load-out one), and making extensive use of multiplex electronics.

This content is only available via PDF.
You can access this article if you purchase or spend a download.