Unattended Floating Production Unit FPU and Attended Floating Storage Offloading FSO

Abstract

Abstract The objective is to present a normally unattended Floating Production Unit (FPU) and an attended Floating Storage Offloading vessel (FSO) concept as an alternative to an unattended FPSO. The unattended FPU operating philosophy is for one year with a two-week maintenance campaign. The study considers a greenfield developed unattended FPU with a rented attended FSO. The focus is the FPU and what is different compared to current design principals for a FPSO. To ensure a lean design, TotalEnergies encouraged to use a Justify-in based approach, starting with the simplest design and then justifying required functions and systems. The FPU has fewer systems but the ones onboard needs to meet requirements of the core process, be robust, simple, reliable and easy to maintain. The focus is on simplification, reliability and efficiency, allowing the use of robotics as supporting tools. Study focus has been on topsides layout, grouping critical equipment into retrievable Plug and play modules on a one-deck solution constituting a series of individual pancakes, robots friendly design for inspection, operation and maintenance support and, material handling and intervention. Key differences for the unattended FPU concept vs a typical conventional attended FPSO have been identified. Equipment dry weight for different systems for the unattended FPU vs an attended FPSO has been assessed. There is considerable reduction in weight for the unattended FPU, driven by simplifications or elimination of functions. Topside dry weight has been assessed −50% lower than an attended FPSO, based on equipment weight and on ratio of structural weight since the unattended FPU layout is designed on a one-deck solution. CAPEX and OPEX of the unattended FPU and attended FSO have been assessed respectively −33% lower and −64% lower than an attended FPSO. Environmental footprint is reduced primarily as a consequence of having a power from shore delivered with green energy and because of reduced transportation and logistics. The novelty is to propose an environmentally friendly and economical concept driven by simplicity, reliability and efficient maintenance. The application of NUF (Normally Unattended Facilities) principles to simple facilities has become an established practice in the industry. TolalEnergies recognizes an opportunity to expand such principles into more complex and larger facilities. The challenge is the willingness to implement new ways of working, update regulatory requirement and be target focused rather than process/regulatory focused.