TEMA offshore imports petroleum products via a Conventional Buoy Mooring (CBM) system into Ghana. The existing system comprises an 18" pipeline between the CBM and Tema Oil Refinery.

However, the system suffers from low operability and shows damage to mooring equipment and so TOML commissioned Project Management International (PMI), in combination with ZLH Consulting Engineers, to carry out a study on the existing system and to propose measures to improve the system.

One of the measures proposed to improve the design of the system was the collection of current and wave data, which was contracted by PMI to MSI.

In March of this year, MSI installed a TRDI 300kHz Acoustic Doppler Current Profiler (ADCP) fitted with wave firmware. The unit has also been fitted with a double external battery canister to allow for at least 2 months uninterrupted data collection and all instruments are moored inside a gimballed stainless steel bottom frame.

Since April this year 4 service visits have already been undertaken to collect data for preliminary design.

Sakkie le Roux from PMI commented: "MSI has provided a very reliable and recommended service. The data collected enables the engineers to confirm that the wave direction as derived from the refraction modelling agrees reasonably well with the measured wave direction.

The current measurements showed that the direction varies more frequently than expected from previous available data. The measured data provided valuable information for the optimisation of the CBM orientation.

Provisional analysis of the recorded data shows a possibility that long waves may also be partly responsible for some of the problems experienced at the CBM."

The measurement campaign is currently ongoing.