Pipeline Bundle Extended Length for Subsea Development

Abstract

The Subsea 7 Pipeline Bundle fabrication facility in Wester, Scotland UK has been utilised for the fabrication, pre-commisioning and launch of Pipeline Bundles in the North Sea and Norweigian Sea regions for over 36 years. Subsea 7 has installed: Three Pipeline Bundles in Australia for Esso’s Bream & Tuna Fields Eight Pipeline Bundles for Elf Exploration Angola Girassol Field Over seventy five Pipeline Bundles installed in the North Sea and Norwegian Sea regions Research and Development work has been conducted to extend the length of a single Pipeline Bundle beyond the current site capacity of 7.7km, thereby further enhancing the Pipeline Bundle technology for longer subsea tie-backs. Pipeline Bundle length extension can be achieved with the use of onshore tie-in methods such as golden welds, mechanical connectors or fabrication at a different site with sufficient length capacity. This paper presents an overview of potential methods that can be used for fabricatation, launch, tow and installation of Pipeline Bundle lengths greater than 7.7km. Case studies for Pipeline Bundle lengths between 8km and 15km inclusive have been analysed as part of the work. The work confirms the feasibility of Pipeline Bundle length extension and the potential for significant reduction in CAPEX for subsea fields requiring long tie-backs. The use of the different connection methods further confirms that the Pipeline Bundle technology can be applied globally once a site with a suitable length is identified. The work presented in the present paper highlights the critical elements associated with the application of Pipeline Bundle Extended Length. Emphasis is made on the Pipeline Bundle control during tow operation based on the companies tow expertise developed over the past three decades.