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New connector enables re-use of Pipeline Bundles

New connector enables re-use of Pipeline Bundles

 

Re-configuration or relocation of subsea equipment transforms the economics of marginal field development

The re-use of subsea infrastructure is widely recognised to be the key to unlocking many challenging fields – marginal fields, stranded reservoirs and longer tie-backs – by significantly reducing both CAPEX and decommissioning costs. In addition, re-use of existing structures makes a significant contribution towards environmental sustainability.

Subsea 7 and OneSubsea, collaborating as Subsea Integration Alliance, are developing a new multi-bore connector which enables the serial subsea connection or reconfiguration of the company’s market-proven Pipeline Bundle product utilizing ROV tooling.

The innovative connector development greatly enhances the versatility of the cost-effective Pipeline Bundle concept by introducing the potential to re-use a Pipeline Bundle (or elements of it) for long-term service with different duty cycles in multiple locations.

“Our unrivalled experience with Pipeline Bundles has demonstrated that they still have considerable remaining integrity at the end of their design life,” says Thomas Sunde, Subsea 7’s Vice President Strategy and Technology.

“Some marginal fields may have potentially short lives, with a number of reservoirs in close proximity to an existing host. In these circumstances, we can use a single Pipeline Bundle for a period, and then redeploy it using the new connector to exploit a different pool.

“Recovery, refurbishment and re-use of Pipeline Bundles is a high-performance concept that greatly reduces capital cost amortizations, making marginal fields viable where they were previously uneconomic.”

The Pipeline Bundle concept

Since the 1980s, Subsea 7 has constructed and installed over 80 Pipeline Bundles, including two in Australia, all assembled and fully tested in controlled onshore conditions before being transported to site.

The finished Pipeline Bundles are transported and installed in position by the efficient Controlled Depth Tow Method (CDTM), a low-stress and low-fatigue process using local anchor-handling tugs which eliminates one of the major technical challenges for the re-use of traditional pipelay systems.

Prefabricated Pipeline Bundles are a smart, simple solution, incorporating all the structures, valve work, pipelines and control systems for field operation contained in a corrosion-free environment within a single, large-diameter carrier pipe.

Onshore fabrication and testing allows all-year installation with simplified campaigns and eliminates the need for specialist pipelay or heavy construction vessels. Pipeline Bundles can operate at pressure and temperature limits beyond conventional tie-back options and deliver active control of the arrival temperature across the production life.

“We have already installed a Pipeline Bundle with the functionality for re-floating and re-positioning, although it is still in service in its original position 11 years after installation,” says Thomas Sunde.

“The ability to bring into play the recycling and re-use of subsea equipment is a hugely exciting proposition which has not been technically feasible until now.”

The multi-bore connector

The new multi-bore connector enables the serial connection of multiple Pipeline Bundle sections to create longer tie-backs of any desired length without intermediate towheads and tie-in spools.

It also allows for altering the length of Pipeline Bundles in the future or changing out a towhead to accommodate high-integrity pressure protection systems, cooling spools, boosting pumps or isolation valves, with options for removal or interchangeability to meet developing field conditions.

The innovative connector development is based on existing and proven technologies and enables the connection of a combination of three pipelines and multiple control tubes in a single diverless operation.

“Being able to design Pipeline Bundles for cost-effective re-flotation, reconfiguration, re-use and even removal creates a completely new insightful type of thinking,” says Thomas Sunde.

“As well as the benefits of cost reduction and project acceleration, the concept is also environmentally considerate. Although the commercial model for re-use and re-purposing is widely understood and utilised for FPSOs, this important new technological development now enables a similarly versatile approach to be adopted for subsea production infrastructure.”

Contributed by Subsea 7

Published: 06-05-2019

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