In June 2013 Saipem was awarded the $3 billion EPCI contract by Total Upstream Nigeria Ltd for the subsea development of the Egina Field, located offshore Nigeria in a water depth of up to 1,700 m.
The Egina field was discovered in 2003 in the OML 130 block, approximately 100 km off the Nigerian coast south of Port Harcourt in the Rivers State. The field’s development calls for 44 subsea wells connected to a 330-metre long FPSO with an oil storage capacity of 2.3 mmbbl.
OML 130’s operator, Total Upstream Nigeria Ltd, and its partners, NNPC, Sapetro, Petrobras and CNOOC, have now started the Egina field development project, their third major deep-water development offshore Nigeria since mid-2005. Total is aiming for start-up at the end of 2017, building to plateau production of 200,000 bbl/d.
Saipem’s UFR (umbilicals, flowlines and risers) contract, the largest in the Company’s history, involves engineering, procurement, fabrication, installation and pre-commissioning of 52 km of oil production and water injection flowlines; 12 flexible jumpers; 2 km of oil export line; 20 km of gas export pipelines; along with installation and commissioning of 80 km of steel tube umbilicals and the mooring of the FPSO and the offshore oil loading terminal (OLT) buoy. Most of the fabrication will be performed in Nigeria, with marine installations to follow during 2016 and the early part of 2017.
The technical challenges
The Egina UFR presents numerous novel aspects and technical challenges, mainly due to the water depth. Chief among these are the qualification and installation of the 20.5-inch flexible oil offloading lines, which are the largest anywhere; the organisation of the riser layout, comprising eight top-tensioned risers including production, gas export and water injection types in a very compact area; and the resolution of the high fatigue loads induced by slugging effect, in particular to the riser base spools.
The 1,250-metre long, steel single hybrid risers (SHRs) will be fully rigid up to the jumper connections to the FPSO. They will be of the same proprietary design as applied for Usan, a previous deep-water UFR and OLT contract assigned to Saipem in 2008 by Total in Nigeria. Compared to steel catenary risers (SCRs), the SHRs present numerous advantages.
Their configuration means that they are virtually fatigue-free, with no particular requirement to counter weld fatigue. Additionally, they can be installed prior to or after arrival of the FPSO to the benefit of the field installation schedule. In addition, SHRs have the advantage of minimising the loads on FPSO hull freeing payloads for modules and equipment.
As for the high slugging fatigue loading, Saipem will develop a suitable spool design, including welds that have to be specifically qualified to combat fatigue in a sour environment.
Turning to marine operations, planned to be carried out beginning 2016 by the FDS and FDS 2 ultradeep-water field development ships and by the Saipem 3000 heavy lift DP vessel, the main technical challenge will be the installation of the risers, which will have to be toptensioned by huge buoyancy tanks of 6-7 m diameter and 50 m in length.
These will be filled with nitrogen to allow dewatering and sustain the water depth. The buoyancy tanks will be bigger than those deployed for the Usan risers, and the potential impact on the installation vessel, combined with weather, requires a very detailed assessment.
It is also worth noting that the particular architecture of the field layout, notably the close distance between consecutive water injection drill centers, will require the utilisation of high performance pipe laying vessels because of the need to control heavy flowline catenaries with multiple in-line structures. Expected dimensions of the spools also require top tier heavy construction vessels. Saipem will address all of these issues by drawing on its experience and technology methodologies from previous deep-water projects, and the solutions should make this a benchmark for future deep-water UFR developments.
The Local Content: a Nigerian project
The Egina project implementation plan confirms Saipem’s strong commitment to Local Content in the Country. The vast majority of fabrication works will be performed at Saipem’s Rumuorlumeni Yard in Port Harcourt. This is an internationalclass fabrication yard and logistics base, with state-of-the-art facilities including new cranes. It is the largest in West Africa in terms of acreage and equipment, has an increased fabrication capacity of 22,000 tonnes/y, and is fully capable of handling the Egina UFR project requirements. The entire Egina UFR project is run from Saipem Contracting Nigeria’s premises in Lagos, and most of the engineering is being performed in Nigeria. One of the main goals of the entire project is to prioritise the use of local vendors. Indeed, Saipem is auditing and qualifying major Nigerian subcontractors to assess the scope of work that they can perform. As part of its strategy of building local capacity and transferring know-how, Saipem also ran an extensive training programme for 60 local engineers to develop the multidisciplinary expertise required for the development of deep-water projects. It covered areas such as cathodic protection, geotechnical, subsea structures, flowlines, risers and installation engineering. Training initially commenced in Lagos, conducted by Saipem experts.
The trainees were then sent to Saipem’s deep-water competence centre in Paris for a minimum duration of three months. After their return, their training continued on the job, and some are now recognised as leaders in their field in Nigeria.