Pazflor in perspective

The complexity and sheer scale of Total's Pazflor project in block 17 offshore Angola – the field covers 600km2, six times the surface area of Paris – was outlined at the recent Subsea Europe conference in Paris by Laurent Villard, the operator's SURF installation engineering leader. Meg Chesshyre listened in.

First Pazflor oil (Oligocene) was achieved on 24 August 2011, 44 months after project sanction in December 2007; the first oil loading – of 950,000 barrels – took place on 1 October 2011. The life time of the facilities is put at 20 years. The field establishes a number of new industry benchmarks: one of the largest projects ever operated by Total; the biggest FPSO to date (processing two different types of oil, with a production capacity of 220,000 b/d and a storage capacity of 1.9 million bbl); the most complex subsea network (11,000t of subsea equipment, 180km of pipelines and 84km of umbilicals), and a global technology first in terms of subsea separation.

The giant FPSO Pazflor in production offshore Angola.

The Pazflor development comprises four fields. Three of them – Hortensia, Perpetua and Zinia in the north – are shallow Miocene reservoirs with 400 million bbl of heavy and viscous oil (17-22°API). These account for 65% of overall reserves. The fourth field – Acacia in the south – is a deeper Oligocene reservoir, with 200 million bbl of 35-40°API light oil. The Miocene reservoirs have been developed with three multi-phase production lines with three subsea gas-liquids separation and pumping units specifically designed, engineered and qualified for the project. The Oligocene reservoir is being developed with a conventional production loop with three manifolds and thermally insulated pipe-in-pipe envelope. Water depths range from 600m to 1200m, with the FPSO located in around 800m.

The project requires 49 wells, and 3000 days of drilling to develop 590 million bbls of reserves. It has involved 32 million manhours and up to 4500 people worldwide, including a peak of 345 in March 2011 within Total alone. There were 25 wells at first oil. The drilling programme, lasting five years, started in March 2009 with the Pride Africa and will involve up to four DP rigs – the Saipem 12000 and West Gemini have also been used. There will be seven producers, five water injectors and two gas injectors into the Oligocene; 18 producers and 17 water injectors into the Miocene.

The purpose-built FPSO was built by DSME in Korea.

Weighing in at 120,000t (hull and topsides), the floater measures 325m x 61m x 32m and has 15 topside modules, plus provision for a future module for upsides. It has accommodation for 180 people in normal operations and up to 240 maximum. First steel was cut in January 2009 and the FPSO left the Korean yard last January.

The vessel's two 18in, 2100m W-shaped oil offloading lines are made up of 375 Trelleborg Trelline bonded hoses, each 12m long, 18in diameter and with 50 bar design pressure, hailed as a world first. Employing these large diameter lines to facilitate a reduction of pressure drop and pumping facilities on the FPSO was subject to a full qualification programme. An SBM-APL consortium was responsible for the buoy, the loading lines and the fibre optic cable.

Laurent Villard.In charge of the installation engineering for the Pazflor project was civil engineer Laurent Villard who joined Total as a consultant in 2006, when the Pazflor tender was launched. Emphasizing the scale of the SURF project, he points out that it involved a consortium of two contractors Technip- Acergy (now Subsea 7) working side by side. There were six main construction vessels and over 40 support vessels and barges co-existing with two to four drilling rigs and other floating hardware. Sequencing was all important, stresses Villard, adding: ‘You have side by side six vessels and these vessels have to interlink and install in the right order.' He is pleased with the result: ‘Things went well. All boats stuck to their planning. The FPSO arrived on time and there were no big difficulties to manage.'

SSU pile installation in block 17.First to arrive in early September 2010 was the Acergy Legend, which remained on location for 364 days. The Acergy Polaris and Acergy Eagle were on site for 130 days and 253 days respectively, Technip's Deep Blue did 98 days and theDeep Pioneer 61 days in two campaigns. Normand Installer, working for SBM-APL, chalked up 93 days in two campaigns.

SURF fabrication was carried out in Lobito (Angola) for the umbilicals, Le Trait (France) for the risers and integrated production bundle fabrication and spooling, and Dande (Angola) for rigid pipe fabrication and spooling, including pipe-in-pipe.

The subsea separation units, apart from the piles, which were manufactured locally, were supplied by FMC in Norway. Between January and June 2010 they underwent site integration tests and shallow water testing at Horten in Norway before being transported by Jumbo Offshore to Angola. They arrived in Luanda Bay in December 2010 and following further tests – made easier by the degree of pre-testing carried out in Norway – they were installed by Polaris the following January.

According to Villard, the criteria for a successful transportation ‘is a very high level of co-operation between the designer of the separator and the transporter, because the contractors were different'. It took months to establish the best configuration for the separators transportation, he notes.

Installation of the 192mm diameter, 3.5km long SSU powering umbilicals had proved challenging due to the size of the umbilical terminations. Each UTH measured 4.5m x 3.5m x 3.5m and weighed 12.2t in air. The Acergy Eagle had to make a separate trip to the quayside to load each umbilical, with installation of each umbilical offshore typically taking three days.

The Pazflor SURF lost time injury frequency was 0.19 per million manhours, against a target of 0.36 for a total of 5,137,009 manhours, Villard confirms. The 12-month offshore installation campaign accounted for some 1.5 million manhours and involved 900 workers. Key to this ‘is that nothing is done without it having been thought about before – procedures, analyses, risk assessments, change management, scheduling – and a professional and constructive relationship with contractors', says Villard.

Sonangol is the block 17 concessionaire. Total (40%) is operator on behalf of partners Statoil (23.33%), Esso (20%) and BP (16.67%). OE 

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