Over 1 million bbls of oil produced in Parque das Conchas

Production has now hit over 1 million bbls of oil at the Parque das Conchas fields 120 km off the coast of Brazil, where ultra deep water and a constant swell makes for tough operating conditions.

A series of technology firsts unlocked major new resources beneath water nearly 2 km deep. Huge technical challenges had to be overcome to bring the fields to production. Remote controlled submarines operating in massive pressures on the ice cold seafloor installed the equipment needed to produce the oil from deep beneath the seabed.

A vast network of wells and pipelines connect reservoirs scattered up to 20 km apart. In a double technical first, oil and gas are separated on the seabed before powerful electric pumps push the oil upwards from the low pressure reservoirs to a specially converted production vessel on the surface that stores it for shipping to shore. Long umbilical cables stretching out from the vessel conduct continuous power and chemicals — vital to prevent frozen solids forming in the oil — to the production machinery far below.

As long term energy demand soars, accessing hard to reach resources such as those at Parque das Conchas will be increasingly vital. To develop the fields economically, the reservoirs of Parque das Conchas were connected through a single production process centred on the converted vessel.

Production from the fields is the latest step in the company’s strategy of delivering an additional 1 million bpd of oil and gas production in the coming years.

At the heart of the Parque das Conchas project — formerly known as BC-10 — is a floating production, storage and offloading vessel (FPSO) with the capacity to produce up to 100 000 bpd and 50 million ft3/d of natural gas. Shell is the operator with a 50% share with partners Petroleo Brasileiro (Petrobras) holding 35% and India’s ONGC Campos Ltd. a 15% share.

‘Oil and gas will continue to play a major part in meeting the world’s growing energy demands, and bringing Parque das Conchas production onstream marks an important milestone for oil production in the region,’ says Shell Upstream Americas Director Marvin Odum.

Pumping up the oil
To combat the low pressure in the reservoirs, Shell installed 1500 hp. electric submersible pumps on the seabed. Each pump uses the thrust of a Formula 1 car engine to drive the oil to the surface. The oil travels through specially developed steel pipes that are flexible enough to move with the ocean’s persistent swell.

Production comes from the Abalone, Ostra and Argonauta B-West fields lying at depths of between 950 - 2500 m below the seabed, southeast of the city of Vitória. Some 5000 men and women worked together to overcome huge technical challenges to make Parque das Conchas a reality. The first phase of the project now onstream involves nine producing wells. A second phase currently in planning will focus on the Argonauta O North field.

The pressure of water on the seabed is approximately 180 bar — 180 times the average pressure at sea level — and too much for a human diver to bear. Temperatures are near freezing and the sun’s rays cannot penetrate. Remotely operated submarines steered by crews at sea level installed the pumps, wellhead machinery and other equipment piece by piece.

Adding to the challenges, the resources lie in small to medium sized reservoirs under a seabed terrain made unstable by shifting sands. To prevent sand, mud and shale from falling back into the well while drilling, Shell pumped in a mix of synthetic oil with additives under high pressure to hold the hole open. And the geological makeup of each reservoir varies, with the density of oil ranging from very heavy in the Ostra field to light in Abalone.

Some of the oil at Parque das Conchas has a high gas content. To prevent this gas from entering the pumps and damaging them, the company installed machines to separate the oil from gas on the seabed, rather than on a surface platform or onshore. Instead of burning this gas off, it is being pumped back into the Ostra field for storage until construction of a gas export pipeline system is complete.

Round the clock operations
The oil is pumped up to an FPSO because of the remote location of the fields, far from any pipelines. The vessel — a converted tanker — can store nearly 1.5 million bbls of oil for shipment to shore, enough to fill over 600 million soft drink cans. Laid end-to-end, the cans would circle the world twice. From there, tankers take it to markets.

Published on 11/12/2009

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