An unusual platform concept was brought into play at Sonangol P&P's Morsa West field.
When Angola Drilling Company (ADC) approached UWG last year for help in developing Sonangol P&P’s Morsa West field, the company already had a concept in mind – a rig-assembled conductor platform (RACP). The objective was to turn this unusual concept into a reality in the shortest time and for the lowest cost possible.
Alan MacKenzie, who led the work at UWG, explains the challenges presented by the project. “Using the well conductors to support a simple wellhead platform is an elegant way of limiting the costs of oilfield development in shallower water, especially if, as was the aim in this case, you can install the entire structure from a drilling rig and without any special heavy-lift vessels.
“The engineering, however, is not so straightforward. As well as taking into account the usual stresses experienced by the conductors, you have to consider the weight loading that they have to withstand. In fact, the nature of the platform demands you combine the normal conductor riser analysis with the structural engineering elements of the design.”
The Morsa West RACP has four 30-inch OD conductors set in 17 m of water, supporting a deck weighing 65 t. A team of UWG engineers based in Norwich carried out the detailed design work, which was subjected to independent verification, in the space of just three months. Fabrication of the drilling template and the topsides at a yard in Cape Town, South Africa, was completed by August of 2005, and then all attention turned to Angola and the work offshore.