A low motion FPSO design hosting SCR & TTR in harsh environment

Abstract

In the development of remote offshore oil and gas fields with minimal or no infra-structure, the Floating Production Storage and Offloading (FPSO) unit is the preferred solution. The FPSO has the advantage of providing the required storage in the hull and direct offloading to tankers of opportunity. Steel Catenary Risers (SCRs) are the preferred solution in wet-Tree applications due to their simplicity, robustness and low Capital cost (CAPEX) and Operational cost (OPEX) compared to other riser options. Also, Top Tensioned Risers (TTRs) have their well-known advantages in allowing direct vertical access to production wells and hence enhanced recovery. However, due to its relatively high dynamic motion, conventional FPSO is not a feasible host for TTRs or SCRs in most environments. In this paper, a Low Motion FPSO (LM-FPSO) design with the ability to host SCRs and TTRs is presented and evaluated for applications in deepwatcr field developments. A case study is prepared to compare the technical and commercial aspects of a field development in 250m water depth using a conventional FPSO to those using a wet-Tree LM-FPSO supporting SCRs and a dry-Tree LM-FPSO hosting TTRs. The constructability, transportability and installability of the new design along with its performance verification through physical scale model testing are discussed and presented in this paper. ？2017, Offshore Technology Conference.