STEEL JACKET STRUCTURES FOR THE NEW EKOFISK COMPLEX IN THE NORTH SEA.

Decommissioning is an increasing market sector which has been gradually gathering momentum particularly in the North Sea. The forecast expenditure for removing existing platforms increases with time. This comes together with the increasing complexity of the decommissioning operation. Experience and expertise in this field are key for success. Saipem have been contracted to perform a number of ‘removals’ ranging from subsea templates, subsea pipelines, seabed debris clearance, jacket structures and topside modules. This paper provides an account of our experience gained over the last 20 years performing decommissioning activities. The paper presents the evolution of the techniques developed and focuses in particular on the Lift and Tow method developed after 2004 for a number of subsea applications. Problems always materialise post contract award due to inadequate data. The paper gives a detailed description of the Lift and Tow method along with various innovative techniques developed for this method, ranging from lifting operations supported by motion forecasting through to personnel access onto the structures.

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Field Implementation of RBI for Jacket Structures

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.1951777 ◽

2005 ◽

Vol 127 (3) ◽

pp. 220-226 ◽

Cited By ~ 16

Author(s):

Michael Havbro Faber ◽

John D. Sørensen ◽

Jesper Tychsen ◽

Daniel Straub

Keyword(s):

Sensitivity Analysis ◽

Stress Ratio ◽

Inspection Planning ◽

Membrane Stress ◽

Steel Jacket ◽

The North ◽

Large Numbers ◽

Structural Details ◽

Jacket Structures ◽

The North Sea

After a brief outline of the simplified and generic approach to reliability- and risk-based inspection planning, focus is set on a recent application of the methodology for the planning of in-service NDT inspections of fixed offshore steel jacket structures in the Danish part of the North Sea. The study includes a sensitivity analysis performed for the identification of relevant generic parameters such as the bending to membrane stress ratio, the design fatigue life, and the material thickness. Based on the results of the sensitivity analysis, a significant number of inspection plans were computed for fixed generic parameters (predefined generic plans) and a database named iPlan was developed from which inspection plans may be obtained by interpolation between the predefined generic plans. The iPlan database facilitates the straightforward production of large numbers of inspection plans for structural details subject to fatigue deterioration, as illustrated by an example in the paper.

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20 Years Decommissioning Experience - Evolution of Innovative Solutions

10.3940/rina.ijme.2015.a4.344 ◽

2015 ◽

Vol 157 (A4) ◽

pp. 263-274

Keyword(s):

North Sea ◽

Market Sector ◽

The North ◽

Innovative Solutions ◽

Jacket Structures ◽

The North Sea ◽

Subsea Pipelines ◽

Innovative Techniques

"Decommissioning is an increasing market sector which has been gradually gathering momentum particularly in the North Sea. The forecast expenditure for removing existing platforms increases with time. This comes together with the increasing complexity of the decommissioning operation. Experience and expertise in this field are key for success. Saipem have been contracted to perform a number of ‘removals’ ranging from subsea templates, subsea pipelines, seabed debris clearance, jacket structures and topside modules. This paper provides an account of our experience gained over the last 20 years performing decommissioning activities. The paper presents the evolution of the techniques developed and focuses in particular on the Lift and Tow method developed after 2004 for a number of subsea applications. Problems always materialise post contract award due to inadequate data. The paper gives a detailed description of the Lift and Tow method along with various innovative techniques developed for this method, ranging from lifting operations supported by motion forecasting through to personnel access onto the structures."

Download Full-text