About the Asset

The Dana operated Western Isles FPSO is serviced by a gas export / import pipeline that routes through the Tern platform into the main gas pipeline system (FLAGS) for the northern North Sea (via North Cormorant). The current gas export / import route infrastructure is planned to CoP between 2023 – 2024. Without any modifications the Western Isles will be gas deficient.

The Western Isles FPSO requires gas to sustain production, supply the FPSO with power and associated gas for key operations and is also required to restart production via gas lift.

Katoni’s role in supporting the Client

Katoni performed a study to further refine the ‘start-up’ requirements and ‘stay-up’ requirements for the Western Isles FPSO to address gas deficiency and thereby negating the need for a gas export / import pipeline system. Recommended options from the Phase 2 study which were evaluated in detail were:

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Start of Grid {

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Start up requirement

Stay up requirement

Start up compressor

Gas reformer

Gas compressor blowdown:

a. semi-pressurised shutdown

b. fully-pressurised shutdown

Diesel generators

PWRI system / existing Seawater

Injection Pump upgrades

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} End of Grid

Each option was evaluated to address specific areas of concern, develop more detailed project plans, map out specific risks to projects and frame the solution(s) in a more robust way to support project decision making. A detailed schedule and CAPEX/OPEX summary were developed for each option and combination of options and ranked accordingly to aid the client in selecting the most economical solution which balanced cost, risk, emissions, operational efficiency and vulnerability.

Understanding Client’s Needs & Delivery

The recommended start-up solution was installation of a Kick Off Compressor in combination with installing a partial blowdown facility to retain production gas for start-up.

The recommended stay-up solution was installation of a new Diesel Generator and upgrades to the existing oversized Seawater Injection system.