Case study: West Africa

Working in ultra-deep water and on soft sediments, Benthic provided our client with essential parameters for FPSO anchor and pipeline design.

The Project

Location: West Africa
Date: December 2009 – January 2010

Overview

Located off the West African coast, this deepwater development lies in water depths ranging from 1,100 to 1,400 meters over an area of around 200 square kilometers. Central to the project is the installation of the Floating Production, Storage and Offloading (FPSO) unit, which will have a processing capacity of 160,000 barrels of oil a day and a storage capacity of approximately 1.8 million barrels. But before deploying the FPSO and associated pipelines, our client needed timely and accurate data for anchor and foundation design.

Our Role

Our client engaged Benthic as its offshore site investigation partner, with responsibility for:

  • Gathering geotechnical data
  • In-situ testing
  • Lab testing
  • Engineering interpretation of soil characteristics

Our objective was to provide comprehensive parameters for the design of the FPSO anchors and foundations, as well as a detailed assessment of soil and pipeline interactions for optimal pipeline placement.

Challenges

The project required us to work in ultra-deep water (up to 1,404.5m) on extremely soft, sensitive soils, all within the logistically challenging environment of Africa’s west coast.

Achievements

Drawing on PROD’s unmatched abilities in ultra-deepwater, we were able to complete our client’s extensive testing program in just 16 days of seabed operations, including 1,200m of sampling and in situ testing at 66 borehole locations, all at a depth of more than 1000m. This equated to approximately 93m of borehole progression per operating day. We were also able to use a variety of testing techniques in each deployment, including piston sampling, CPT, and cyclic BPT, providing a richer and more comprehensive data set.

PROD’s unique footing design also allowed us to collect data from the mud line, even while operating on very soft deepwater clays, with important implications for pipeline placement. 

Having collected and analyzed the geotechnical data and managed the advanced laboratory testing program, we provided our client with engineering design parameters preliminary design calculations for the anchor and foundation geometries, facilitating rapid and low-risk project development.