Subsea Redevelopment Concept and FEED Study

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Client: Confidential

Asset: FPSO and Existing Subsea Field

Location: East Coast of India

Year: 2021-2023

FPSO Turret Hardy Oil


Background and Objective

The existing field has subsea wells connected to the Floating Production Unit (a converted semi-submersible unit spread moored in the field). The operator intended to mobilise a new Floating Production Storage and Offloading unit to permanently moored location and reconnect the new and future subsea wells. Nobleseas Engineering conducted a subsea redevelopment concept and FEED  study. The primary objectives of the study were as per below: 

  • Evaluate the design of subsea infrastructure and hook up architecture for compliance with the applicable industry standards including safety standards as established by OISD for the purpose of granting CTO (Consent to Operate).
  • Identify new subsea hardware requirements including evaluation of the current available subsea architecture & equipment.
  • Evaluate and recommend solutions which shall result in overall cost optimisation and reduction time to production of First oil.
  • To recommend cost effective solutions / alternate items to optimise the CAPEX and
  • Identify additional work that may be essential to complete the verification of all the technical requirements to be ready for the next phase of project execution.


The subsea engineering study aimed at subsea redevelopment with a focus on interface limitations to new host facility and integrity status of existing subsea infrastructure.

The key activities covered the proposed subsea engineering study are as follows:

  • Conducted subsea feasibility study against the new host facility and subsea redevelopment of existing as well as the future wells.
  • Conducted subsea FEED study optimising subsea layout, validate compliance, and prepared master equipment list.
  • Conduct high level flow assurance feasibility study to validate proposed line sizing and lengths and provide recommendations.
  • FEED study covered cost optimisation assessment, risk and findings and review of documentations to obtain Consent to Operate.
  • Prepared technical specification of subsea equipment for tendering purpose and conducted technical bid evaluation of all the SURF items including ancillary components. The bid evaluation also involved interface with OEMs.
  • Provided high-level cost estimate for new equipment
  • Conducted re-laying feasibility study of existing and new flowlines, risers and umbilicals including hook up to new FPSO.

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