Total has gone public with its latest giant West Africa deepwater fpso project - Egina (SEN, 29/7) - in 1,600m in Nigeria.

This is the second development on the OML 130 licence and will be moored just 20km southwest from the Akpo production unit.

Unlike some of its earlier West African fpso’s, this one has been designed not just for the main field, but for future tiebacks as well. Storage capacity on the 330m long production ship will be 2.3mmbbls.

Different strokes

Total has gone for some different technology here, notably on the SURF system. The riser system has been dubbed a single line top tension riser (STTR) - a new concept or at least a new acronym to SEN.

It does sound a bit like a more commonly named single leg offset riser (SLO) with pipe- in-pipe risers supported at the bottom with a piled foundation and at the top with a buoyancy tank 100m below the surface and linked to the fpso with a flexible jumper. The PIP risers will allow provide riser-based gas lift through the annulus.

The reservoir is a classic shallow West African turbidite which will require looped flowlines for flow assurances purposes and single water injection flowline with the wells teed off it.

The shallow reservoir presents notable drilling challenges for the 2,300m long horizontal production wells which kickoff just 200m below the seabed.

Flow assurance is a big problem here with the wellstream temperature one of the lowest seen in the region. This requires an even stricter cooldown regime than often needed in West Africa. Added to this are larger diameter risers and flowlines which will present design and installation issues.

The cooldown issues may have been the reason that Total has opted for FMC hardware which comes with its own proprietary insulation. The $1.2bn deal includes trees, controls and the six-slot manifolds. Saipem has been awarded the SURF contract.