Total has achieved the world’s first subsea gas/liquid separation.
The French group has reported that the Acergy Polaris finished installing three subsea separation units (SSU) for the Pazflor project in 800m water on January 30, offshore Angola on block 17.
It said that Pazflor was the first project to deploy a development plan based on gas/liquid separation at the mudline (seafloor) spanning several reservoirs, and that this milestone technological innovation will make it possible to meet the challenge of producing the heavy, viscous oil contained in three of the four reservoirs in this vast deepwater development.
Pazflor comprises four reservoirs.
One, Acacia, was formed around 25million years ago in the Oligocene and contains light oil.
However, Perpetua, Zinia and Hortensia are younger, dating from the Miocene, and were themselves formed between five and seven million years ago.
They contain more problematic oil that is heavier and much more viscous.
The subsea production system for Pazflor’s three Miocene reservoirs includes three subsea separation units (SSUs), each consisting of four retrievable packages; a gas-liquid separator, two hybrid pumps to boost the liquids and a manifold to distribute the effluents to the separator and the pumps.
Purpose-designed for Pazflor, the hybrid pumps are said by Total to be another world first.
They combine multiphase stages, compatible with the presence of gas in the liquid, and a centrifugal stage, to improve efficiency.
The SSUs are the culmination of several years of R&D work and a rigorous qualification programme.
They ensure the optimum efficiency and reliability of this vital production equipment.
Total said: “With our new-found proficiency in subsea separation technology, combined with a standard production loop, we have demonstrated that we were right to decide to develop two types of oil with very different properties that require two separate subsea production systems.”
Both systems will be connected to a floating production, storage and off-loading vessel (FPSO).
Following its departure from South Korea on January 18, the Pazflor FPSO is currently at sea en route to Angola.
Total operates Angola’s block 17 and its fields with a 40% interest. Partners comprise Statoil with 23.33%, Exxon with 20% and BP with 16.67%.
Meanwhile, after many months of negotiation, Tullow Oil has at last signed a memorandum of understanding with the Ugandan government that apparently satisfies the African state’s taxation concerns.
The deal means that UK-listed Tullow, China National Offshore Oil Corporation (CNOOC) and Total can get on with an ambitious multiple oil fields development project, near Lake Albert in the African Rift Basin.
Tullow said that the MoU provided a process that is expected to result in the resolution of the impasse created by the Heritage Oil and Tullow Oil tax situations, the development of the Kingfisher Field and the grant of extension in respect of block 1 and parts of block 3A – in recognition of the fact that time has been lost.
The impasse was also said to have been caused in part by consent by the government for Tullow to purchase Heritage’s interests in the Lake Albert Basin and the farm-downs to CNOOC and Total.