Constructability Review for an FPSO project for a Confidential Client


A Constructability Review, managed and motivated by Process Safety Matters, succeeded in compressing the FPSO project risk by 25%, thus reducing the required funding guarantee by $50m.


The Client aims to tie in additional oil and gas wells to its FPSO.

FPSO picture

The purpose of the project is to fully develop the new resources. In order to achieve this, new wells (production and injection) will be tied-back to existing infrastructure. There will be new subsea architecture inclusive of manifolds, flowlines, umbilical and risers. The production from the additional wells could either extend the current production plateau or add to the current peak production thereby elevating the existing production plateau.

Two FEED cases are being considered for the FPSO modifications required to support this additional production:

The Plateau Extension Case FEED will define the FPSO topsides modifications required with extending plateau oil production.

The Expansion Case considers a further upside case to the FPSO capacities which potentially increases production rates up to 160kbopd, 250mmscfd and 300kbwpd for the oil, gas and water injection systems respectively. 


The main aspects of the Expansion Case are as follows:

  • Introducing 2 x 100% gas turbine drive Seawater Injection Pumps
  • Change-out of Gas dehydration system (Gas Filter Separator and TEG Contactor only) suitable for 250 mmscfd gas capacity
  • Running the two Main Gas Compressor trains in parallel
  • Upgrade of Oil train capacity to 160kbopd by exchanger and Crude transfer pump modifications 

Constructability Review

The Client decided to carry out a Constructability Review. Their Consultant was commissioned to find an independent chairman to manage and lead this review. They turned to Process Safety Matters who in turn set up a Pre-meeting which generated the following Review goals:

  • Identify key constructability/destructability related risks associated with the Expansion Phase of the FPSO Project
  • Highlight the main impediments to achieving safe and timely construction
  • Stretch Target – Construction can be achieved with no major SD

Process Safety Matters further led the Pre-meeting to develop a working methodology which included the following key aspects:

  • Identify Expansion Phase Construction Activities
  • Develop relevant Constructability Criteria including a triaging traffic light system to highlight the Construction Phase Pinch Points.
  • For each System, review each Activity step chronologically against Constructability Criteria
  • Record the review findings on a customised spreadsheet (see below)
  • Where significant risks are identified, which are not appropriately mitigated:
    • Generate actions to reduce residual risk to ALARP
    • Assign actionee who is responsible for the action being closed out

Assign close out date

Recording Spreadsheet

Recording Spreadsheet Picture

Benefits of Constructability Review

The Optimised cost of the project is $1000m. However, as with all such projects, a risk premium has been added, in this case 25% or $250m. As a result of carrying out the Constructability Review following the Process Safety Matters Methodology, has reduced this risk significantly, in the order of 20% or $50m.