The golden block

Block 17 has shone brightly for French operator Total and its partners. Now with the fourth development – CLOV – in production, Audrey Leon details how lessons learned and local content proved to be key to Total’s success offshore Angola.

Construction of the CLOV FPSO in South Korea. Photos from Total.

To say that Total has experienced success offshore Angola would be an understatement. One block alone, Block 17 (lovingly referred to as the “Golden Block” by the company), has birthed several major developments including Girassol in 2001, followed by Dalia in 2006, Pazflor in 2011, and now CLOV, its flagship, which came online in 2014.

At this year’s Offshore Technology Conference, the US$8 billion CLOV mega-project was discussed by several principal project managers, who all shared the opinion that Total’s previous experience in the block allowed them to bring CLOV into production successfully.

The CLOV development is some 87mi (140km) offshore Angola’s capital city, Luanda, and some 25mi (40km) north-northwest of Girassol. The project consists of four fields (Cravo, Lirio, Orquidea, and Violeta) with proven and probable reserves of over 500 MMbbl and a capacity to produce 160,000 b/d.

In her OTC paper, CLOV project director Genevieve Mouillerat, said that the CLOV complex shares similar geology to the rest of the Block 17 license — unconsolidated turbidite sandstone. Lirio was the first field discovered, in 1998, when the operator spud the Lirio-1 well and found a significant accumulation in the Oligocene with a large gas cap. Discoveries at Orquidea and Violeta followed, proving heavier Miocene oil.

With two different oil types to produce, Total decided on a development concept that could incorporate both the Oligocene and Miocene accumulations, Mouillerat said.

Illustration of CLOV’s subsea field. Photo from FMC Technologies.

To produce the fields, Total drilled 34 wells — 19 production and 15 water injection — which Mouillerat said required the work of two drillships (the West Gemini and the Ensco DS-1) and the equivalent of 2500 drilling days. The wells, along with eight manifolds, were connected by 120mi (180km) of subsea pipelines to an FPSO unit, which sits in water depths ranging 3600-4593ft (1100-1400m).

The CLOV FPSO has to be capable of processing the two specific grades of crude oil produced from the lighter (32-35°) Oligocene and heavier (20-30°) Miocene reservoirs. Measuring 305m long by 61m wide, the vessel has a storage capacity of 1.78 MMbbl. It has a single processing train for commingled light and heavy crudes, capable of handling 229,000 b/d of total liquids, and providing 319,000 b/d of water injection. The processing system includes a wash tank system similar to what Total used on Usan off Nigeria, Mouillerat said.

Total also instituted a “no flaring in normal operation” policy for the FPSO, said Patrick Vallot, the FPSO manager on CLOV, during his OTC presentation. “The total volume of gas flare is equivalent to the power consumption of the whole continent,” he said. In his OTC paper (25918-MS), Vallot clarified that while to some eliminating the pilot flare may seem rather small, by the end of the project’s life it adds up to become a significant volume that would otherwise be wasted, and can be added toward the export tally.

Because of the policy, Mouillerat said that the topside is equipped with a compression capacity of 6.5 MMcm/d.

Vallot also highlighted Total’s commitment to reducing its environmental footprint, not only on this project but around the globe. Total and partners chose to create the newbuild CLOV FPSO with all-electric, variable-speed drives, which Vallot said is a rare technology for offshore because it is more commonly used onshore for refineries or chemical plants.

The CLOV FPSO control room during startup.

Developing CLOV

Total and partners opted for a subsea multiphase pump (MPP) system to boost the commingled fluid and enhance oil recovery. The MPP system is driven by helicon-axial pumps, which Mouillerat said provides flow-boosting for the heavier oil because the fields have both low reservoir pressure and a high-viscosity well stream.

In 2011, Aker Solutions and Framo Engineering won a US$10 million (NOK 80 million) deal to supply a 10.6km multi-phase power and control umbilical for the project.

In 2010, FMC Technologies won a $520 million contract to manufacture and supply CLOV’s subsea production equipment. The company was to provide 36 subsea trees, wellhead and controls, eight manifolds, two work systems, and associated tooling and equipment.

Mouillerat said the subsea xmas tree system on the project were similar to what has been used on past Total projects, 10,000 psi-rated vertical tree, weighing 39-ton. Each tree was equipped with a chemical injection valve, an insert choke valve and a multiphase flowmeter. There are four, 12in four-slot production manifolds at Cravo and Lirio fields, and four, 10in four-slot manifolds on Orquidea and Violeta fields.

As for the project’s SURF development, Total once again benefitted from prior lessons learned from Girassol, Mouillerat said. The company opted to adapt the system into a single flowline loop, thus reducing the total length of flowlines and reducing the number or riser towers used, which, in this case, is down to two “new generation” riser towers.

Mouillerat said Total opted to use pipe-in-pipe for the flowline concept, using a 10.5mi (17km) flowline ring at Cravo-Lirio, which consists of a 12in flowline in a 16in carrier pipe, while at Orquidea-Violeta, the company used a 13mi (21km) dual flowline loop consisting of a 10in flowline in a 14in carrier pipe.

As part of a $1.3 billion contract signed in 2010, Subsea 7 carried out engineering, fabrication and installation work on 80mi (130km) of pipes: 25mi (40km) of pipe-in-pipe production lines, 37mi (60km) of water- injection lines, 20mi (32km) of gas export lines, the two hybrid riser towers, one single hybrid riser at the end of the gas export line, 50mi (80km) of subsea umbilicals, and 37 spools and 15 jumpers. Subsea 7 also handled installation of manifolds and subsea pumps, and pre-commissioning activities. The company utilized the Seven Borealis, Seven Eagle, and Acergy Legend to carry out the project.

Local content

An aerial view of the CLOV FPSO.

By utilizing both the local workforce and local goods, Total was able to make the CLOV project a reality.

While the CLOV FPSO was constructed by Korean shipbuilder Daewoo Shipbuilding and Marine Engineering’s (DSME) Okpo yard, Francois Bichon, who also served as CLOV project director, spoke about how Total and its project partners utilized two local yards — Paenal (in Port Amboim) and Sonamet — to complete FPSO work.

Considered to be the youngest yard, Paenal completed 7700-tonne of fabrication and assembly, and 1.5 million man hours without a lost time incident. Bichon said the CLOV FPSO was the first berthed in Angola and the first module integration there. In terms of yard upgrades, Bichon noted the addition of a heavy lift crane for topsides (2500-tonne and a quay extension from 80m to 480m). At Sonamet, 23,000-tonne of fabrication occurred and 26,000-tonne of assembly.

Bichon stressed the importance of local content to the OTC crowd, calling it the driving force behind CLOV, but also a “necessity” for operating companies. “It is part of the unwritten contract with the country we’re working in,” he told the OTC audience. “It’s essential.

Operators have to be involved because it can become their problem later.” Bichon noted that it is up to the operator to implement and carry out a safety culture, as well as to provide the right amount of supervision to ensure safety targets.

Michael Meyer, training coordinator for the CLOV project, highlighted Total’s commitment to hiring a local workforce to operate its facilities, during his OTC presentation. He said that in 2011, Total embarked on a 20-month program and selected 51 candidates to fill 45 potential positions. By December 2012, the training program, conducted only in English, granted 36 upstream operator certifications, with 12 going to work on the CLOV FPSO, and 24 filing positions on other Block 17 FPSOs. Training also included an immersive training simulator with a 3D model designed by DSME and developed by Siemens with Total e-nnovation department.

Total and partners celebrated a milestone on Block 17 in late May, achieving 2 billion bbl produced from Block 17, and with CLOV’s production added, the block has achieved 700,000 b/d.

Total operates Block 17 with a 40% interest alongside partners Statoil (23.33%), Esso Exploration Angola Block 17 (20%) and BP Exploration Angola (16.67%). Sonangol is the concessionaire of the license.