An oil field located about 80km west of the African coast at the water depth of 818m had reached its end of economic life. The facilities and wells would need to be Decommissioned and Abandoned (D&A). The Floating Production Storage & Offloading (FPSO), which was the key component of the facilities, would need to undergo the Disconnection and Demobilization (D&D) phase. The objective of this campaign was to restore the field back to its safe condition whilst minimising the environmental impact, complying with local and international legislative and at the same time delivering the Abandonment & Decommissioning (A&D) in line with good industry decommissioning practices at the most optimize cost. Upon completion of the D&D, the FPSO would require to return to her original base in the South East Asia (SEA).

This paper discusses a case study for a D&D campaign and activities of the FPSO which includes the Subsea, Umbilical, Riser and Flowline (SURF) and mooring system. One of the crucial areas during the execution phase was pertinent to the management and disposal of the hazardous waste that is subjected to transboundary movement as per the relevant convention. Amongst the hazardous waste were Natural Radioactive Occurrence Material (NORM), low specific activity (LSA) material, hydrocarbon sludge and contaminated water. It is necessary for the FPSO to be free from the above said hazardous waste for her to be accepted by the receiving base country.

This paper also describes the actual experiences and lessons learnt which can be applied in future projects.

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