On a remote ship off Nigeria’s coast, four pairs of eyes stare at a screen showing live footage from below the ocean’s surface. It is the moment of truth. The engineers carefully lower a 30-tonne metal box – packed with pipes and valves – more than a kilometre down to the seabed.
The production module is designed to sit on the seabed, gathering oil and gas from new wells for pumping to a processing facility the height of a 12-storey building that floats on the sea surface.
Before they can install it, the team uses a system of cables and joystick-controlled underwater robots with on-board cameras to remove pipeline caps from an existing module, operating since 2005. Then they must slot the new module on top.
“Usually we would do an assembly test of all the equipment on land first,” says Uche Okonkwo, lead engineer for undersea equipment on the Bonga North West deep-water project. “But in this case, we had to fit new equipment to an existing installed structure without this step.”
A window of opportunity
A remote survey showed that the existing module had not corroded and still matched its original measurements. Even so, they could not be certain the new module would fit exactly.
“We had no margin for error,” says Uche. “Carrying out this task in such a remote location requires a lot of investment – and incredible precision.”
Adding to the pressure, the team had only a small window of opportunity to install the new equipment. They took advantage of planned maintenance on the floating production facility, which was partly shut down. No extra production time would be lost.
After eight hours in total, the module was lowered into place and was locked tight – a perfect fit.