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West Africa regulatory requirements in use of a CALM offloading system for a spread-moored FPSO?

asked May 27, 2015 in Offshore-Upstream by jakangaru (2,010 points)
Are there any West Africa regulatory requirements at all that mandate the use of a CALM offloading system for a spread-moored FPSO?

2 Answers

+1 vote
answered May 27, 2015 by gagonza (3,020 points)
I haven’t seen anything so I would go with “common practice in the neighborhood” and with practices elsewhere in West Africa whereby all of the major producers have opted for the safer and more reliable CALM option. The CALM was also a plus for adding local content. We therefore assumed that the offloading system needed to be approved by the powers and that these powers favored CALM’s.

Some may consider tandem offload from a spread-moored FPSO, no CALM. The only way I can think of as to how to improve the safety of offloading would be to have a dedicated fleet of DP tankers, just as they have in the North Sea.
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answered May 31, 2015 by Normandy (21,000 points)
No, there is no such requirement that I am aware off.

However, SPMs have been used in relatively mild areas such as West Africa and around the world to transfer product to/from onshore and offshore production and storage facilities. Connecting to a SPM is a standard operation with tug assistance, station-keeping is easier to manage since the tanker has the ability to freely weathervane. An SPM can be located remotely from the FPSO (about a mile) therefore increasing the distance from the tanker in comparison to side by side and tandem operations and resulting in less tanker FPSO interaction.

The main concern with SPMs is the relatively high CAPEX. The technical issues are greater in deep waters: the mooring line footprint will have to suit the subsea field layout. At the time of the study the export lines and their connection to the buoy were raising new design issues, particularly regarding fatigue in the case of steel lines. Since that time the technological gaps for deepwater CALM appear to have been solved.

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