Case studies

UK flag Increasing production and extending asset life across mature UKCS basin, United Kingdom

Image gallery
  • Successful delivery of Apache’s biggest ever shutdown and turnaround, spanning 22,000 man-hours over two weeks
  • £12 million debottlenecking project delivered safely, within budget and on schedule, resulting in enhanced production rates
  • Various contract renewals and extended scope


Project: Commissioning, engineering and construction services for Apache’s UK assets

Client/partner: Apache

Location: UK North Sea

Value: US$160 million per annum

Challenging the status quo in a mature basin

With a portfolio of ageing assets in the mature UKCS basin, increasing production and extending expected asset life was the key aim for our client. 

Apache had already invested more than US$1.2 billion to renovate mature and significant UKCS assets before Petrofac was awarded an onshore engineering and offshore construction contract.

Safely extending the life of aging assets

We transitioned Apache’s five UK North Sea assets - the Forties Alpha, Bravo, Charlie, Delta and Echo – and had 340 employees working for Apache, onshore and offshore.

Already well-known for our experience in best in class minor modification services, we provided a modifications programme for Apache which included multidiscipline projects across all the Forties’ existing systems.

Our scope was expanded to cover commissioning and we completed a £12 million debottlenecking project for the Forties Alpha and Forties Delta platforms.

Flow bottlenecks had been caused by existing topsides equipment, including vessels, gas scrubbers, production gas coolers, pumps and valves, not being sized to take increased amounts of gas. Modifications increased the deep gas lift flow levels, enhancing production rates.

Our reputation for delivering shutdown projects for our clients on time and within budget was cemented, when we successfully delivered Apache’s biggest ever shutdown and turnaround spanning 22,000 man-hours over two weeks.

Having worked closely with Apache to deliver several highly successful projects on the Forties field, our responsibilities were extended further to cover onshore engineering and both onshore and offshore construction services to all the Apache North Sea assets, including the Beryl field and at the SAGE gas plant. Our scope was also extended to include topside brownfield and greenfield activity in addition to interfacing with subsea contractors.

Spotlight on: Apache's Bacchus tieback project

Petrofac played a vital role in the delivery of Apache’s Bacchus tieback project, with services ranging from detailed engineering and design, procurement and fabrication management to offshore construction and commissioning. The project achieved first oil just two years after the Design phase started.

Bacchus is a high pressure/high temperature field 6.8 km north east of Forties Alpha. It was produced through three wells and tied back to the Alpha platform via a subsea pipeline bundle including production, produced water injection and heating, gas lift, chemical services, and power and control umbilicals.

This project involved many subcontractors and our scope included topside modifications on Alpha:

  • Installation of the caisson riser
  • Location and installation of the primary equipment
  • Process tie-ins
  • Position and hook up of the subsea control equipment
  • Modifications to the safety, controls and electrical systems

Recognition and reward from our client

Petrofac’s recognition and reward came in the form of various contract renewals and scope extensions.


Petrofac has consistently delivered against our expectations on the varied projects we have undertaken on the Forties development, including our biggest ever shutdown and turnaround project. They have also shown a relentless focus on improving safety performance.