Gamba export sealine replacement

This client operates and extracts oil from numerous fields in the western part of Gabon. Crude oil is treated and exported from the Gamba Terminal to tankers through a 30-inch offshore export line. This is connected to a single buoy mooring via a pipeline end manifold (PLEM) and 16-inch floating hoses.

The challenge

The existing export sealine was installed in 1986 and was in need of replacement, having reached the end of its lifecycle. The sealine was originally designed as a single line with no provision for inspection, pigging or cleaning facilities. In order to improve the operating performance and maintenance, our client wanted to replace the single existing line with a looped 22-inch sealine system and pigging facilities to allow for inspection and operational cleaning.

The solution

Van Oord Offshore was contracted by this client to replace the existing sealine (both onshore and offshore), install a new PLEM, flush the newly installed system, inspect the single buoy mooring and decommission the old one. Van Oord Offshore contracted Bluestream as their diving sub-contractor for the project. We were responsible for the preparation and execution of the diving activities, which were carried out from the DP2 DSV Stril Server.

The scope included:

  • Flooding of the pre-installed sealines
  • Recovery of PLEM tow wires
  • Single buoy mooring preparation 
  • Grouting of piles
  • Laydown head removal
  • Spool installation
  • Concrete mattress installation
  • Floating hose removal and installation
  • Subsea hose removal and installation
  • Decommissioning of pipeline and PLEM
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